GLI1-Altered Mesenchymal Tumors With ACTB or PTCH1 Fusion: A Molecular and Clinicopathologic Analysis

Mesenchymal tumors with GLI1 fusions or amplifications have recently emerged as a distinctive group of neoplasms. The terms GLI1-altered mesenchymal tumor or GLI1-altered soft tissue tumor serve as a nosological category, although the exact boundaries/criteria require further elucidation. We examined 16 tumors affecting predominantly adults (median age: 40 years), without sex predilection. Several patients had tumors of longstanding duration (>10 years). The most common primary site was soft tissue (n = 9); other sites included epidural tissue (n = 1), vertebra (n = 1), tongue (n = 1), hard palate (n = 1), and liver (n = 1). Histologically, the tumors demonstrated multinodular growth of cytologically uniform, ovoid-to-epithelioid, occasionally short spindled cells with delicate intratumoral vasculature and frequent myxoid stroma. Mitotic activity ranged from 0 to 8 mitoses/2 mm2 (mean 2). Lymphovascular invasion/protrusion of tumor cells into endothelial-lined vascular spaces was present or suspected in 6 cases. Necrosis, significant nuclear pleomorphism, or well-developed, fascicular spindle-cell growth were absent. Half demonstrated features of the newly proposed subset, "distinctive nested glomoid neoplasm." Tumors were consistently positive for CD56 (n = 5/5). A subset was stained with S100 protein (n = 7/13), SMA (n = 6/13), keratin (n = 2/9), EMA (n = 3/7), and CD99 (n = 2/6). Tumors harbored ACTB::GLI1 (n = 15) or PTCH1::GLI1 (n = 1) fusions. The assays used did not capture cases defined by GLI1 amplification. We also identified recurrent cytogenetic gains (1q, 5, 7, 8, 12, 12q13.2-ter, 21, and X). For patients with available clinical follow-up (n = 8), half were disease free. Half demonstrated distant metastases (lungs, bone, or soft tissue). Of cases without follow-up (n = 8), 2 were known recurrences, and 1 was presumed metastasis. Our results imply a more aggressive biological potential than currently reported. Given the possibility for metastasis and disease progression, even in cytologically bland, nested tumors, close clinical surveillance, akin to that for sarcoma management, may be indicated. The term GLI1-altered mesenchymal tumor with malignant potential is proposed.

Synovial Sarcoma of the Gastrointestinal Tract

We report the clinicopathologic and immunohistochemical features of 18 cases of confirmed primary synovial sarcoma of the gastrointestinal tract. The neoplasms arose in 10 women and 8 men ranging in age from 23 to 81 years (mean: 50; median: 57.5 years). The tumors for which size was known ranged from 1.8 to 15.0 cm (mean: 5.2; median: 5.1 cm). Microscopically, 14 synovial sarcomas were of the monophasic type, 2 were biphasic, and 2 were poorly differentiated. Immunohistochemical analysis of 4 cases showed strong, diffuse staining for SS18::SSX (4/4 cases). Pancytokeratin and EMA immunohistochemistry were performed on 13 and 9 tumors, respectively, and each showed patchy-to-diffuse staining. By reverse-transcription PCR, 3 cases were positive for the SS18::SSX1, and 2 cases were positive for the SS18::SSX2 gene fusion. Six cases contained an SS18 gene rearrangement by fluorescence in situ hybridization, and next-generation sequencing identified an SS18::SSX2 gene fusion in one case. Clinical follow-up information was available for 9 patients (4 months to 4.6 years; mean, 2.8 y; median: 29 months), and one patient had a recent diagnosis. Three patients died of disease within 41 to 72 months (mean, 56 months) of their diagnosis. Five patients were alive without evidence of disease 4 to 52 months (mean, 17.6 months) after surgery; of whom 1 of the patients received additional chemotherapy treatment after surgery because of recurrence of the disease. A single patient was alive with intraabdominal recurrence 13 months after surgery. We conclude that synovial sarcoma of the gastrointestinal tract is an aggressive tumor, similar to its soft tissue counterpart, with adverse patient outcomes. It is important to distinguish it from morphologically similar gastrointestinal tract lesions that may have different treatment regimens and prognoses.

MRI T2 mapping assessment of T2 relaxation time in desmoid tumors as a quantitative imaging biomarker of tumor response: preliminary results

Objectives

Because size-based imaging criteria poorly capture biologic response in desmoid-type fibromatosis (DF), changes in MRI T2 signal intensity are frequently used as a response surrogate, but remain qualitative. We hypothesized that absolute quantification of DF T2 relaxation time derived from parametric T2 maps would be a feasible and effective imaging biomarker of disease activity.

Methods

This IRB-approved retrospective study included 11 patients with DF, managed by observation or systemic therapy, assessed by 3T MRI. Tumor maximum diameter, volume, and T2-weighted signal intensity were derived from manual tumor segmentations. Tumor:muscle T2 signal ratios were recorded. Two readers measured tumor T2 relaxation times using a commercial T2 scanning sequence, manual ROI delineation and commercial calculation software enabling estimation of reader reliability. Objective response rates based on RECIST1.1 and best responses were compared between size-based and signal-based parameters.

Results

Median patient age was 52.6 years; 8 subjects were female (73%). Nine patients with longitudinal assessments were followed for an average of 314 days. Median baseline tumor diameter was 7.2 cm (range 4.4 - 18.2 cm). Median baseline T2 was 65.1 ms (range 40.4 - 94.8 ms, n=11); median at last follow-up was 44.3 ms (-32% from baseline; range 29.3 - 94.7 ms, n=9). T2 relaxation times correlated with tumor:muscle T2 signal ratios, Spearman p=0.78 (p<0.001). T2 mapping showed high inter-reader reliability, ICC=0.84. The best response as a percentage change in T2 values was statistically significant (mean -17.9%, p=0.05, paired t-test) while change in diameter was not (mean -8.9%, p=0.12).

Conclusions

Analysis of T2 relaxation time maps of DF may offer a feasible quantitative biomarker for assessing the extent of response to treatment. This approach may have high inter-reader reliability.

Discoidin Domain Receptor Tyrosine Kinase 1 (DDR1) Is a Novel Therapeutic Target in Liposarcoma: A Tissue Microarray Study

BACKGROUND

Liposarcoma is the most commonly diagnosed subtype of soft tissue sarcoma. As these tumors often arise near vital organs and neurovascular structures, complete resection can be challenging; consequently, recurrence rates are high. Additionally, available chemotherapeutic agents have shown limited benefit and substantial toxicities. There is, therefore, a clear and unmet need for novel therapeutics for liposarcoma. Discoidin domain receptor tyrosine kinase 1 (DDR1) is involved in adhesion, proliferation, differentiation, migration, and metastasis in several cancers. However, the expression and clinical importance of DDR1 in liposarcoma are unknown.

QUESTIONS/PURPOSES

The purposes of this study were to assess (1) the expression, (2) the association between DDR1 and survival, and (3) the functional roles of DDR1 in liposarcoma.

METHODS

The correlation between DDR1 expression in tumor tissues and clinicopathological features and survival was assessed via immunohistochemical staining of a liposarcoma tissue microarray. It contained 53 samples from 42 patients with liposarcoma and 11 patients with lipoma. The association between DDR1 and survival in liposarcoma was analyzed by Kaplan-Meier plots and log-rank tests. The DDR1 knockout liposarcoma cell lines were generated by CRISPR-Cas9 technology. The DDR1-specific and highly selective DDR1 inhibitor 7RH was applied to determine the impact of DDR1 expression on liposarcoma cell growth and proliferation. In addition, the effect of DDR1 inhibition on liposarcoma growth was further accessed in a three-dimensional cell culture model to mimic DDR1 effects in vivo.

RESULTS

The results demonstrate elevated expression of DDR1 in all liposarcoma subtypes relative to benign lipomas. Specifically, high DDR1 expression was seen in 55% (23 of 42) of liposarcomas and no benign lipomas. However, DDR1 expression was not found to be associated with poor survival in patients with liposarcoma. DDR1 knockout or treatment of 7RH showed decreased liposarcoma cell growth and proliferation.

CONCLUSION

DDR1 is aberrantly expressed in liposarcoma, and it contributes to several markers of oncogenesis in these tumors.

CLINICAL RELEVANCE

This work supports DDR1 as a promising therapeutic target in liposarcoma.

Intratendinous Calcified Chondroid Mesenchymal Neoplasm: A Case Report

Introduction

We present a case report concerning calcified chondroid mesenchymal neoplasms (CCMN), a novel category of tumors that exhibit chondroid formation and contain fibronectin 1-receptor tyrosine kinase fusions.

Case Report

Our report focuses on a 73-year-old female patient who presented with pain in her right hip and gluteal region. Initially, the condition was misdiagnosed as calcific tendinitis based on X-ray imaging. However, a subsequent magnetic resonance imaging (MRI) revealed a solid lobulated mass originating from the right hamstring tendon origin, exhibiting heterogeneously hypointense T1-weighted signal, heterogeneously isointense proton density fat-suppressed signal, and heterogeneous contrast-enhancement compared to skeletal muscle. Further, investigation through computed tomography (CT) demonstrated intratumoral calcifications accompanied by erosive changes in the adjacent right ischial tuberosity. Histologic examination of a CT-guided biopsy confirmed the presence of large calcium pyrophosphate crystal deposits, along with benign chondroid tissue, thus supporting the diagnosis of CCMN. Notably, there is considerable overlap in the imaging characteristics of CCMN and the more commonly encountered calcific tendinitis (calcium hydroxyapatite depositional disease). Contrast-enhanced MRI findings play a crucial role in distinguishing between these two conditions.

Conclusion

To the best of our knowledge, this is the first documented report describing the imaging features of CCMN across multiple modalities, including radiography, CT, and MRI.

Presentation of a Smooth Muscle Hamartoma in the Bulbar Conjunctiva of an Adolescent Boy: A Case Report and Review of Literature

PURPOSE

The aim of this study was to describe a novel presentation of conjunctival smooth muscle hamartoma and review the histopathologic findings of this entity.

METHODS

A 17-year-old African American adolescent boy presented with a pink, nontender lesion of the right bulbar conjunctiva that did not improve with medical management. He had no previous medical or ocular history. The lesion was excised.

RESULTS

Histopathologic examination disclosed morphologically benign smooth muscle bundles within the substantia propria that stained positively for smooth muscle actin, vimentin, and desmin consistent with the diagnosis of a smooth muscle hamartoma.

CONCLUSIONS

Although congenital smooth muscle hamartomas of the conjunctiva have been rarely reported in the literature, this is the first described case of a smooth muscle hamartoma presenting in adolescence in the bulbar conjunctiva. This lesion should be considered in the differential diagnosis for adolescents with similar appearing lesions.

Angioleiomyoma in a 52-year-old female wrist: A case report

Angioleiomyoma is a benign soft tissue tumor arising from vascular smooth muscle and most commonly presents in the lower extremities. We report a case of a 52-year-old right-hand dominant woman who presented with a 2-year history of intermittent, nonradiating left wrist pain, which she described as achy in nature without numbness or tingling. A focused physical examination revealed no edema, no obvious skin changes; there was tenderness over the volar-radial aspect of the left wrist, with an underlying firm, mobile, and palpable soft tissue mass. There was no prior history of trauma or surgery to the affected area. Ultrasound (US) examination demonstrated a 0.6 × 0.6 × 0.4 cm well-defined, oval, hypoechoic soft tissue mass within the volar radial soft tissues of the left wrist. The lesion abutted the radial artery without signs of calcification or necrosis. Color Doppler showed little to no vascularity within the mass nor radial artery thrombosis. Histological analysis revealed an angioleiomyoma arising from the radial artery wall. A case presentation like this would most commonly be due to a volar ganglion cyst; however, it is important to consider other soft tissue masses in differential diagnosis, such as angioleiomyoma, as treatment varies significantly.

Anaplastic Kaposi Sarcoma: A Clinicopathologic and Molecular Genetic Analysis

Kaposi sarcoma (KS) is a human herpesvirus 8 (HHV8)-associated vascular proliferation that most often involves the skin. Rarely, KS shows marked nuclear atypia or pleomorphism; such examples are known as "anaplastic" KS. This poorly characterized variant often pursues an aggressive course; little is known of its genetic landscape. This study evaluated the clinicopathologic and genomic features of anaplastic KS. We identified 9 anaplastic KS cases from 7 patients and 8 conventional KS cases, including a matched conventional KS and primary metastasis anaplastic KS pair from a single patient (anaplastic KS diagnosed 9 years after conventional KS). All patients with anaplastic KS were men, aged 51 to 82 years, who had locally aggressive tumors predominantly affecting the soft tissue and bone of the lower extremities (5/7 patients). Four patients were known to be HIV positive (all on antiretrovirals), 2 were HIV negative, and 1 was of unknown HIV status. The tumors showed angiosarcoma-like or pleomorphic spindle cell sarcoma morphology. Plasma cell-rich chronic inflammation and hemosiderin deposition were commonly present. Single-nucleotide polymorphism-based chromosomal microarray analysis showed the anaplastic KS cohort to demonstrate highly recurrent whole chromosome (chr) gains of chr 7, 11, 19, and 21, which primarily affected olfactory and G protein-coupled receptor signaling and losses of chr6_q and chrY. Compared with conventional KS, anaplastic KS cases showed significantly more total copy number alterations and more frequent gains of chr7 and chr11_q13.1 (MARK2, RELA, and ESRRA, including high copy number gain in 1 case). Pathway analysis demonstrated that these gains preferentially affected genes that facilitate cyclin-dependent cell signaling. Furthermore, anaplastic KS cases were phylogenetically distinct from conventional KS cases, including the patient-matched primary metastasis anaplastic KS pair and conventional KS. Our study is the first to demonstrate that a more complex genome and distinct copy number alterations distinguish anaplastic KS from conventional KS. Gains of chr7 and chr11_q13.1 appear central to biological transformation.

Ancient Schwannoma Presenting at the Cauda Equina: A Report of a Rare Case

Ancient schwannoma is an uncommon variant of schwannoma. While many reports have presented defining histologic and clinical features of ancient schwannoma, there are only a very few cases in the literature, to our knowledge, of ancient schwannoma presenting at the cauda equina. The current report of ancient schwannoma presenting at the cauda equina adds to the literature and discusses the identification of specific histologic characteristics, the role of conservative medical management, surgical resection, and prognostication in this select subset of patients.

Rhabdomyosarcoma Arising in Inflammatory Rhabdomyoblastic Tumor: A Genetically Distinctive Subtype of Rhabdomyosarcoma

"Inflammatory rhabdomyoblastic tumor" (IRMT) is a recently coined name for a distinctive soft tissue neoplasm characterized by slow growth, a dense histiocytic infiltrate, scattered, bizarre-appearing tumor cells with morphologic and immunohistochemical evidence of skeletal muscle differentiation, a near-haploid karyotype with retained biparental disomy of chromosomes 5 and 22, and usually indolent behavior. There are 2 reports of rhabdomyosarcoma (RMS) arising in IRMT. We studied the clinicopathologic and cytogenomic features of 6 cases of IRMT with progression to RMS. Tumors occurred in the extremities of 5 men and 1 woman (median patient age, 50 years; median tumor size, 6.5 cm). Clinical follow-up (6 patients: median, 11 months; range 4-163 months) documented local recurrence and distant metastases in 1 and 5 of 6 patients, respectively. Therapy included complete surgical resection (4 patients) and adjuvant/neoadjuvant chemo/radiotherapy (6 patients). One patient died of disease, 4 were alive with metastatic disease, and one was without evidence of disease. All primary tumors contained conventional IRMT. Progression to RMS appeared as follows: (1) overgrowth of monomorphic rhabdomyoblasts with diminished histiocytes, (2) monomorphic spindle cell morphology with variably pleomorphic rhabdomyoblasts and low mitotic activity, or (3) morphologically undifferentiated spindle cell and epithelioid sarcoma. All but one were diffusely desmin-positive, with more limited MyoD1/myogenin expression. All RMS arising in IRMT, either primary or metastatic, demonstrated widespread loss of heterozygosity with retained heterozygosity of chromosomes 5 and 20, and all but one displayed additional gains and losses involving loci containing oncogenes/ tumor suppressor genes, most often CDKN2A and CDKN2B. RMS arising in IRMT have unique clinicopathologic and cytogenomic features, warranting classification as a distinct, potentially aggressive RMS subtype. It should be distinguished from other RMSs, particularly fusion-driven spindle cell RMS and pleomorphic RMS.

NR4A3 fusions characterize a distinctive peritoneal mesothelial neoplasm of uncertain biological potential with pure adenomatoid/microcystic morphology

A focal adenomatoid-microcystic pattern is not uncommon in peritoneal mesothelioma, but tumors composed almost exclusively of this pattern are distinctly rare and have not been well characterized. A small subset of mesotheliomas (mostly in children and young adults) are characterized by gene fusions including EWSR1/FUS::ATF1, EWSR1::YY1, and NTRK and ALK rearrangements, and often have epithelioid morphology. Herein, we describe five peritoneal mesothelial neoplasms (identified via molecular screening of seven histologically similar tumors) that are pure adenomatoid/microcystic in morphology and unified by the presence of an NR4A3 fusion. Patients were three males and two females aged 31-70 years (median, 40 years). Three presented with multifocal/diffuse and two with a localized disease. The size of the individual lesions ranged from 1.5 to 8 cm (median, 4.7). The unifocal lesions originated in the small bowel mesentery and the mesosigmoid. Treatment included surgery, either alone (three) or combined with hyperthermic intraperitoneal chemotherapy (two), and neoadjuvant or adjuvant chemotherapy (one case each). At the last follow-up (6-13 months), all five patients were alive and disease-free. All tumors were morphologically similar, characterized by extensive sieve-like microcystic growth with bland-looking flattened cells lining variably sized microcystic spaces and lacked a conventional epithelioid or sarcomatoid component. Immunohistochemistry confirmed mesothelial differentiation, but most cases showed limited expression of D2-40 and calretinin. Targeted RNA sequencing revealed an NR4A3 fusion (fusion partners were EWSR1 in three cases and CITED2 and NIPBL in one case each). The nosology and behavior of this morphomolecularly defined novel peritoneal mesothelial neoplasm of uncertain biological potential and its distinction from adenomatoid variants of conventional mesothelioma merit further delineation as more cases become recognized.

Sinonasal Myxoma: A Distinct Entity or a Myxoid Variant of Desmoid Fibromatosis?

Sinonasal myxoma (SNM) is a rare benign mesenchymal tumor that arises in the sinonasal cavity or maxilla and almost exclusively affects young children. Currently, it is considered a specific entity, but its molecular characteristics have not been reported. Lesions diagnosed as SNM and odontogenic myxoma/fibromyxoma (OM/OFM) were identified from the participating institutions, and the clinicopathologic features were recorded. Immunohistochemistry for β-catenin was performed on all cases with available tissue. Next-generation sequencing (NGS) was performed on all SNM cases. Five patients with SNM were identified, including 3 boys and 2 girls with an age range of 20-36 months (mean: 26 months). The tumors were well-defined, centered in the maxillary sinus, surrounded by a rim of woven bone, and composed of a moderately cellular proliferation of spindle cells oriented in intersecting fascicles in a variably myxocollagenous stroma that contained extravasated erythrocytes. Histologically, the tumors resembled myxoid desmoid fibromatosis. Three tested cases showed nuclear expression of β-catenin. In 3 tumors, NGS revealed intragenic deletions of APC exons 5-6, 9 and 15, or 16, respectively, with concurrent loss of the other wild-type copy of APC, predicted to result in biallelic inactivation. The deletions were identical to those that occur in desmoid fibromatosis, and copy-number analysis raised the possibility that they were germline. In addition, one case showed possible deletion of APC exons 12-14, and another case exhibited a CTNNB1 p.S33C mutation. Ten patients with OM/OFM were identified, including 4 women and 6 men (mean age: 42 years). Seven tumors involved the mandible, and 3 the maxilla. Histologically, the tumors differed from SNM, and all cases lacked nuclear expression of β-catenin. These findings suggest that SNM represents a myxoid variant of desmoid fibromatosis that often arises in the maxilla. Because the APC alterations might be germline, genetic testing of the affected patients should be considered.

Osteogenic Sarcoma of the Head and Neck: Is Chemotherapy Needed?

OPINION STATEMENT

Head and neck osteosarcoma (HNOS) is a rare subtype of sarcoma that most commonly arises in the mandible or maxilla. Treatment for HNOS typically involves a multidisciplinary and multimodal approach depending on the size, grade, and histological subtype. Surgery by sarcoma-experienced head and neck surgeons and orthopedic oncologists remains a crucial component of treatment in all subtypes of HNOS, particularly for those with low-grade histology, which can be treated definitively with surgical resection if negative margins are obtained. Negative surgical margins are of utmost prognostic importance, and neoadjuvant or adjuvant radiation should be considered in patients with positive (or anticipated positive) margins/residual postoperative disease. Current data favors the use of (neo)adjuvant chemotherapy in patients with high-grade HNOS to improve overall survival but must be individualized to weigh benefits and risks of the short- and long-term effects of treatment. Our center uses a multidisciplinary treatment plan and notes anecdotal improvement in treatment outcomes with a combined surgical and ifosfamide-containing chemotherapeutic approach with radiotherapy for local control if positive margins. Large volume cohorts and adequate randomized control trials assessing the efficacy of chemotherapy in HNOS are scant and additional research and multi-institutional collaboration are needed to study polychemotherapeutic and radiation treatment regimens and outcomes more adequately.

Highlighting the Diversity of Desmoplastic Small Round Cell Tumor: A Case Series

Desmoplastic small round cell tumor (DSRCT) is a rare malignant tumor that occurs mainly in the retroperitoneum of children and young adults. In its prototypical form, DSCRT displays characteristic morphology with nested primitive small round cells in a desmoplastic stroma and a distinctive immunophenotype with polyphenotypic differentiation. However, DSCRT can also exhibit a broader clinical, histologic and immunohistochemical spectrum and, therefore, cause diagnostic difficulties. Given that DSCRT is an aggressive and nearly universally fatal disease, making the correct diagnosis is critically important. Herein, we report three patients with DSRCT and unusual clinical, morphologic or immunohistochemical characteristics, in order to highlight its remarkable diversity and increase awareness of this unusual, distinctive neoplasm.

Transcriptional Profiling Supports the Notochordal Origin of Chordoma and Its Dependence on a TGFΒ1-TBXT Network

Chordoma is a rare malignant tumor demonstrating notochordal differentiation. It is dependent on brachyury (TBXT), a hallmark notochordal gene and transcription factor, and shares histologic features and the same anatomic location as the notochord. In this study, we perform a molecular comparison of chordoma and notochord to identify dysregulated cellular pathways. The lack of a molecular reference from appropriate control tissue limits our understanding of chordoma and its relationship to notochord. Accordingly, we conducted an unbiased comparison of chordoma, human notochord, and an atlas of normal and cancerous tissue using gene expression profiling to clarify the chordoma/notochord relationship and potentially identify novel drug targets. We found striking consistency in gene expression profiles between chordoma and notochord, supporting the hypothesis that chordoma develops from notochordal remnants. We identified a 12-gene diagnostic chordoma signature and found that the TBXT/transforming growth factor (TGF)-β/SOX6/SOX9 pathway is hyperactivated in the tumor, suggesting that pathways associated with chondrogenesis are a central driver of chordoma development. Experimental validation in chordoma cells confirms these findings and emphasizes the dependence of chordoma proliferation and survival on TGF-β. Our computational and experimental evidence provides the first molecular connection between notochord and chordoma and identifies core members of a chordoma regulatory pathway involving TBXT. This pathway provides new therapeutic targets for this unique malignant neoplasm and highlights TGF-β as a prime druggable candidate.

Erratum to "COVID-19 vaccine-associated granulomatous mass mimicking a sarcoma: A case report" [Radiology Case Reports 17 (2022) 2775-2778]

[This corrects the article DOI: 10.1016/j.radcr.2022.05.035.].

Systemic Chemotherapies Retain Antitumor Activity in Desmoid Tumors Independent of Specific Mutations in CTNNB1 or APC: A Multi-institutional Retrospective Study

PURPOSE

Determine whether specific CTNNB1 or APC mutations in patients with desmoid tumor were associated with differences in clinical responses to systemic treatments.

EXPERIMENTAL DESIGN

We established a multi-institutional dataset of previously treated patients with desmoid tumor across four U.S. sarcoma centers, including demographic and clinicopathologic characteristics, treatment regimens, and clinical and radiographic responses. CTNNB1 or APC mutation status was determined from prior pathology records, or archival tissue was requested and analyzed by Sanger sequencing and/or next-generation sequencing. Evaluable patients with mutation results were analyzed to determine clinical progression-free survival (cPFS), RECIST 1.1 PFS (rPFS), time to next treatment (TTNT), and overall survival (OS). Kaplan-Meier analysis and Cox proportional hazards regression were performed to identify differences in cPFS, rPFS, TTNT, and OS by mutation subtype, desmoid tumor location, and treatment regimen.

RESULTS

A total of 259 evaluable patients were analyzed for at least one of the survival outcomes, with 177 patients having mutation data. First- and second-line cPFS, rPFS, and TTNT were not significantly affected by mutation subtype; however, APC-mutant desmoid tumors demonstrated nonstatistically significant inferior outcomes. Extremity/trunk desmoid tumor location and treatment with doxorubicin-based, methotrexate/vinca alkaloids and sorafenib regimens were associated with better clinical outcomes compared with surgery or "other" therapies, including estrogen-receptor blockade and imatinib. OS was significantly worse with APC or CTNNB1 negative/other mutations.

CONCLUSIONS

Mutation subtype did not affect responses to specific systemic therapies. APC mutations and nonextremity desmoid tumor locations remain prognostic for worse outcomes, and earlier initiation of systemic therapy for these higher-risk desmoid tumors should be prospectively evaluated. See related commentary by Greene and Van Tine, p. 3911.

COVID-19 vaccine-associated ganulomatous mass mimicking a sarcoma: a case report

Several studies have previously documented the development of complications stemming from injection with one of the various COVID-19 vaccines. No study, however, has discussed the spontaneous development of a soft tissue mass shortly after a COVID-19 vaccine injection. We report on 66-year-old female with concerns of a growing shoulder mass, 2 weeks after receiving a COVID-19 vaccine booster. Initial work-up with X-ray and MRI was concerning for a soft tissue neoplasm, specifically a soft tissue sarcoma. Subsequent ultrasound guided biopsy demonstrated a benign granulomatous lesion. No further management was required as the lesion spontaneously resolved during a 3-month follow-up period.

Retroperitoneal Cystic Adenopecoma with Genetic Analysis: A Rare Neoplasm

Lymphangiomyomatosis is a member of the PEComa family, and usually involves the pulmonary parenchyma of middle-aged females. Infrequently, it may involve abdominal and retroperitoneal lymph nodes, and rarely it has been described to be associated with fallopian tube-type ciliated epithelium co-existing in one neoplasm. To increase our understanding of this unusual tumor, we describe the morphology and genetics of one case and review the literature. We present the case of a 50-year-old female found to have 12.5 and 7.7 cm cystic retroperitoneal masses, describe its unique pathological features and review the literature on the previously reported cases. Based on its unique morphological, immunohistochemical, and molecular features we propose the term adenoPEComa to represent this entity. This case represents a rare example of adenoPEComa with lymphangiomyomatosis of the lymph nodes. It is the first example that has undergone next-generation sequencing revealing a mutation in TSC2 making it a confirmed member of the PEComa family of tumors.

Inhibition of CDK7-dependent transcriptional addiction is a potential therapeutic target in synovial sarcoma

Synovial sarcoma is typical aggressive malignant without satisfactory treatment outcome in adult series. Cyclin-dependent kinases (CDKs) in transcription have been considered promising molecular targets in cancer. Among these, CDK7 has been shown to play important roles in the pathogenesis of malignancies. However, the modulation mechanism of CDK7-regulated transcription in synovial sarcoma is unknown. In the present study, we aim to determine the expression and function of CDK7 in the transcription cycle of RNA polymerase II (RNAP II), and evaluate its prognostic and therapeutic significance in synovial sarcoma. Results showed that overexpression of CDK7 correlates with higher clinical stage and grade, and worse outcomes in clinic. High CDK7 expression was confirmed in all tested human synovial sarcoma cell lines and CDK7 was largely localized to the cell nucleus. Downregulation through siRNA or inhibition with the CDK7-targeting agent BS-181 exhibited dose-dependent cytotoxicity and prevented cell colony formation. Western blots demonstrated that inhibition of CDK7 paused transcription by a reduction of RNAP II phosphorylation. Blocking CDK7-dependent transcriptional addiction was accompanied by promotion of apoptosis. Furthermore, the CDK7-specific inhibitor reduced 3D spheroid formation and migration of synovial sarcoma. Collectively, our findings highlight the role of CDK7-dependent transcriptional addiction in human synovial sarcoma. CDK7-specific cytotoxic agents are therefore promising novel treatment options for synovial sarcoma.

Aneurysmal bone cyst and osteoblastoma after neoadjuvant denosumab: histologic spectrum and potential diagnostic pitfalls

The use of denosumab to treat giant cell tumors of bone (GCT) and other giant cell-containing bone tumors has become more common. While the clinicopathologic features of denosumab-treated giant cell tumors of bone have been well-illustrated, descriptions of other denosumab-treated bone tumors are very limited. Surgical pathology files of two institutions and consultation files from two authors were searched for denosumab-treated aneurysmal bone cysts and denosumab-treated osteoblastomas. Clinicopathologic features were reviewed and analyzed. We identified four patients with denosumab-treated bone tumors other than GCT from our surgical pathology and consultation files, including two aneurysmal bone cysts and two osteoblastomas. All were treated with denosumab for 0.5-7.0 (median 4.5) months. Radiologically, denosumab-treated tumors showed decreased size with increased ossification and mineralization on CT and heterogeneous intermediate to hypointense signal on MRI. Histologically, denosumab-treated aneurysmal bone cyst contained thin, elongated, curvilinear, and anastomosing strands of bone with empty lacunae, while denosumab-treated osteoblastoma showed circumscribed nodules of woven bone lined by small osteoblasts. Denosumab-treated aneurysmal bone cyst and osteoblastoma showed treatment-related morphologic changes that can mimic other bone neoplasms. Their recognition requires correlation with the clinical history of denosumab use and radiologic findings.

Nonlymphoid Hematopoietic Diseases Presenting in Bone, Soft Tissue, and Other Extranodal Sites

Context.—

Although rare in everyday practice, the initial presentation of hematopoietic neoplasms other than lymphoma in the musculoskeletal system and other extranodal sites can generate challenging diagnostic problems for surgical pathologists.

Objective.—

To review the morphologic and immunophenotypic features of various nonlymphoid hematopoietic diseases presenting at extranodal sites, with emphasis on the inherent diagnostic pitfalls and differential diagnoses of these entities to aid surgical pathologists in their accurate recognition.

Data Sources.—

Cases reviewed herein represent both in-house and consult cases seen at our institution between 2010 and 2021.

Conclusions.—

Entities that present in this way include myeloid neoplasms and histiocytic/dendritic cell neoplasms. These tumors commonly cause nonspecific symptoms, and their histologic appearance can overlap with a variety of benign neoplasms and reactive processes. This can lead to delay in diagnosis and intervention with potentially lifesaving therapy; thus, accurate and expedient recognition is of paramount importance.

Oncological Outcomes in Patients with Appendicular Myxofibrosarcomas: A Retrospective Study

BACKGROUND

Myxofibrosarcoma (MFS) is notorious for its infiltrative growth pattern, making wide excisions difficult to achieve. Our objective was to assess the impact of surgical margins and other factors that affected rates of local recurrence (LR), distant metastasis (DM), and overall survival (OS) of individuals undergoing resection for MFS.

METHODS

We retrospectively reviewed the medical records of 209 patients with appendicular soft tissue sarcomas between January 2012 and June 2018. Of these, 29 patients (14%) were diagnosed with myxofibrosarcoma. These patients underwent a total of 33 resections. The pathological analyses were conducted by an experienced musculoskeletal (MSK) pathologist. Demographics data, operative details, adjuvant therapy, and oncological outcomes were assessed.

RESULTS

Of the 29 patients (33 resections), the overall LR rate was 24% (7/29) and the 2-year LR rate was 17% (5/29). Factors associated with negative oncological outcomes were as follows: tumor size ≤10 cm (2-year local recurrence-free rates (LRFRs), 65%; 95% CI, 44-86%; p=0.02) and positive surgical margins grouped with surgical margins ≤0.1 cm (hazard ratio (HR), 11.74; 95% CI, 1.41-97.74; p=0.02). Chemotherapy and radiotherapy together increased the 2-year LRFR (LRFR, 100%; 95% CI, 100%, p=0.001). Two-year DM and OS rates were 15% and 79%, respectively. Female gender was a predictor of distant metastasis. Local recurrence had a negative impact on overall survival. Intraoperative analysis of resection margin accuracy was 75% (12/16) when non-MSK pathologists were involved but 100% accurate (12/12) when analyzed by an MSK pathologist.

CONCLUSION

Myxofibrosarcomas showed high LR rates after treatment. Close margins (≤0.1 cm) should be considered as a risk factor for LR, and LR is associated with negative overall survival. Neoadjuvant therapy in terms of combined chemotherapy and radiation therapy associates with decreased LR rates. If intraoperative assessment of margins is to be done, it should be performed by an experienced MSK pathologist.

Unexpected Primary Extranodal Marginal Zone Lymphoma of Bone in Amputation and Arthroplasty Specimens

OBJECTIVES

Amputation due to gangrene and arthroplasty for degenerative joint disease are common orthopedic procedures and are expected to increase as populations age. Histopathologic examination of these specimens can identify unsuspected diseases.

METHODS

We reviewed gangrenous amputations and large joint arthroplasty specimens for diagnosis of unexpected lymphoma, January 2014 to January 2020. Pathology and medical records were reviewed to determine diagnosis, treatment, and outcome.

RESULTS

Five cases (0.08%) of unexpected primary extranodal marginal zone lymphoma (MZL) centered in bone were identified in 1,624 amputations for gangrene and 4,163 arthroplasty specimens. The female-to-male distribution was 3:2. Median age was 71 years (range, 62-87). The 3 cases arising in the setting of gangrene involved the first toe phalanges and metatarsals, and the femoral head was involved in all cases of joint disease (2 cases). The bone showed variable (10%-80%) infiltration by dense populations of small lymphoid cells with MZL immunophenotype. One patient died from sepsis 18.5 months after diagnosis; all others are alive with a median follow-up of 27.45 months.

CONCLUSIONS

Histopathologic examination of nonneoplastic orthopedic specimens identifies unexpected primary bone extranodal MZL in a small percentage of cases. This neoplasm may be the result of chronic antigenic stimulation in some circumstances.

Amyloid Arthropathy: A Review

Amyloid arthropathy is a joint disease associated with systemic amyloidosis. Herein, we present a model case and review the clinicopathologic features and pathophysiology of this disorder. Amyloid arthropathy results from elevation of serum amyloidogenic proteins and their deposition as aggregates in synovial fluid and articular tissues. The most common proteins are beta-2-microglobulin in the context of long-term hemodialysis therapy and immunoglobulin light chains associated with plasma cell proliferations. We provide a comprehensive update on the pathogenesis, clinical manifestations, and pathologic features of amyloid arthropathy. We provide detailed insights on amyloid protein deposition and aggregation in joints and proper details for diagnosis.

Unplanned excision of soft tissue sarcoma: does it impact the accuracy of intra-operative pathologic assessment at time of re-excision?

PURPOSE

An "unplanned excision" refers to soft tissue sarcomas excised without planning imaging studies and a diagnostic biopsy, resulting in the presence of residual disease and usually necessitating a re-excision procedure. We aimed to assess the impact of previous unplanned excisions on the intra-operative pathologic assessment at the time of re-excision, in terms of need to perform repeat assessments and the accuracy to predict margin status of the final pathologic specimen.

METHODS

Data was collected for all patients with extremity soft tissue sarcoma who had undergone wide local excision limb salvage surgery or amputation between 2012 and 2017. Intra-operative pathologic assessment with frozen sections was performed in all cases and was classified as negative, negative but close (< 1 mm), and positive.

RESULTS

A total of 173 patients with extremity soft tissue sarcoma were included, 54 in the unplanned excision group and 119 in the planned excision group. The accuracy of intra-operative pathologic assessment to predict the margin status on final pathology was similar between groups (87% unplanned vs. 90.7% planned excisions). However, the need for repeat intra-operative pathologic assessment and subsequent resection due to microscopically positive margins was found to be higher within the unplanned excision group ((p = 0.04), OR = 3.2 (95% CI: 1.1-9.1, p = 0.048)).

CONCLUSIONS

Intra-operative pathologic assessment of resection margins had a similar accuracy in planned and unplanned excisions; however, unplanned excisions showed a higher risk of re-resection during the same surgical setting.

Mesenchymal Neoplasms of Salivary Glands: A Clinicopathologic Study of 68 Cases

Salivary gland neoplasms are uncommon, and most exhibit epithelial differentiation. Mesenchymal neoplasms of the salivary gland are rare, and the incidence ranges from 1.9% to 5%. The aim of this study is to identify the types and clinical-pathological features of mesenchymal salivary neoplasm and review their differential diagnosis. A retrospective search for mesenchymal neoplasms of salivary glands from our institution's pathology archives from the 2004-2021 period and consultation files of one of the authors (AER) was performed. The clinical data were obtained from available medical records, and the histological slides and ancillary studies were retrieved and reviewed. We identified a total of 68 cases that form the study cohort. Thirty-five patients were male, and thirty-three patients were female, with a mean age of 48 years (range, 7 months-79 years), and the male to female ratio was 1:.94. Sixty-three (92.6%) of sixty-eight tumors were benign and included: 38 (56%) lipomas, 9 (13%) hemangiomas, 7 (10.3%) schwannomas, 3 (4.4%) neurofibromas, 3 (4.4%) lymphangioma, 2 (3%) solitary fibrous tumors, 1 (1.5%) myofibroma. Five of sixty-eight (7.4%) were malignant and included: 3 (4.4%) Adamantinoma-like Ewing sarcomas, 1 (1.5%) malignant peripheral nerve sheath tumor (MPNST), and 1 (1.5%) malignant solitary fibrous tumor. The involved sites included: parotid (55), submandibular gland (5), parapharyngeal space (5), buccal mucosa minor salivary gland (2), and sublingual gland (1). Sixty-seven patients underwent surgical resection. One patient with lymphangioma manifested a recurrence/persistence a week post-surgery. One patient with a parotid hemangioma developed post-operative numbness, and another patient developed chronic postauricular pain after surgery. Two patients with MPNST and one patient with adamantinoma-like Ewing sarcoma underwent neoadjuvant chemoradiation and were disease-free after treatment. The remaining 37 patients with available follow-up ranging from 7 days to 96 months (mean, 18 months) had a favorable outcome and were disease-free after treatment. Mesenchymal neoplasms of salivary gland are rare; most are benign and demonstrate adipocytic, endothelial, and schwannian differentiation; awareness of their development is important for adequate diagnosis. The mainstay of treatment is surgical excision, with the extent determined by tumor type. Adjuvant therapy is reserved for high-grade sarcomas and may be given in a neoadjuvant or adjuvant setting.

Novel fusion genes in spindle cell rhabdomyosarcoma: The spectrum broadens

Rhabdomyosarcoma (RMS) encompasses a heterogeneous group of tumors with striated muscle differentiation. RMSs are classified as alveolar, embryonal, spindle cell/sclerosing, and pleomorphic types and molecular analysis of these tumors has identified aberrations that are useful in their further subclassification. Spindle cell rhabdomyosarcoma (SpRMS) is uncommon and has been described with VGLL2 fusions, EWSR1/FUS-TFCP2 rearrangements, and myoD1 mutations-the mutations are associated with significantly different prognoses. In addition, the NCOA2-MEIS1 fusion gene was recently described in two primary intraosseous RMS that contained spindle cell components. Herein, we report three cases of SpRMS harboring different novel fusion genes, one possessing EP300-VGLL3, a second with NCOA2-MEIS1 and CAV1-MET, and the third case had HMGA2-NEGR1 and multiple amplified genes.

Sarcomas with sclerotic epithelioid phenotype harboring novel EWSR1-SSX1 fusions

Undifferentiated sarcomas remain difficult to classify. Despite the remarkable advances in sarcoma classification made by the increased application of RNA sequencing in clinical practice, the unexpected result of a novel gene fusion raises further questions regarding the tumor histogenesis and subclassification. In this study, we present two high grade sarcomas with epithelioid phenotype occurring in the deep-soft tissues (shoulder, thigh) of young adults which based on the non-specific pathologic findings were deemed unclassified and subjected to targeted RNA sequencing for further diagnostic interpretation. The results showed an identical EWSR1 exon 7-SSX1 exon 5 fusion. The breakpoints in both genes represent similar hot spots as seen in Ewing sarcoma and synovial sarcoma, generating a fusion transcript predicted to be in frame, and to retain the same protein domains within the fusion oncoprotein. These results were further confirmed by FISH analysis for both break-apart and fusion come-together assays in both genes. Both tumors showed a round to epithelioid morphology associated with extensive stromal hyalinization and necrosis. One case showed scattered psammomatous calcifications. The tumors shared a similar immunoprofile, including reactivity for EMA, CK, TLE1, BCOR, and CD99, while negative for S100, SOX10, CD34, SMA, and desmin. Both cases showed MUC4 positivity (one diffuse, one patchy), while one case showed patchy ALK positivity. One patient developed lymph node metastases, while the other showed no evidence of disease at 6-month follow-up. Neither case fit in any known pathologic categories. Larger series are needed to interrogate if the presence of EWSR1-SSX1 fusion defines a novel pathologic entity of a sarcoma with epithelioid cytomorphology, sclerotic stroma, and epithelial differentiation immunohistochemically.

Pathology of pleomorphic/undifferentiated and dedifferentiated bone neoplasms

Primary malignant bone tumors are uncommon and their accurate classification requires careful correlation of clinical, radiological, and pathologic findings. It is a heterogeneous group of tumors with a wide spectrum of morphology and their biological potential can be of low- or high-grade, depending on their risk for developing metastases. Over the past several decades, the classification of bone sarcomas has remained largely constant. However, some of the tumors have been reclassified and several new entities have emerged. In this review, we will focus on pleomorphic fibrosarcoma/UPS and dedifferentiated bone tumors, discuss their key diagnostic features, differential diagnosis, and their relation to prognosis.

Epithelioid Sarcoma of the Peripheral Nerve: Clinicopathologic Series of Three Cases and Literature Review

OBJECTIVES

Epithelioid sarcoma (ES) rarely arises in the nerve. To increase our understanding of this unusual tumor originating in the nerve, we describe the features of three cases and review the literature.

METHODS

Clinical data, imaging, pathology, treatment, and follow-up are detailed. A systematic literature review was conducted.

RESULTS

Two patients were male and one female; the median age was 24 years. The patients had neurologic symptoms, and the tumors arose in large nerves and ranged from 2.4 to 5.8 cm. The tumors were avid on positron emission tomography-computed tomography and showed increased signal intensity on T2-weighted magnetic resonance imaging. Centered in the nerve, the tumors grew with an infiltrative pattern and encased the nerve fascicles. All were treated with wide resection, and adjuvant treatment included combinations of chemotherapy and radiation. One recurred, and the limb was amputated. Metastases were documented to lymph nodes, lung, pleura, and skin. One patient died of disease after 54 months. Literature review including our cases showed that tumors stained with pancytokeratin (9/9), EMA (4/4), and CD34 (7/7); there was loss of INI1 in all six cases tested.

CONCLUSIONS

ES rarely arises in the peripheral nerve, and its infiltrative nature often requires morbid surgery. The differential includes a variety of benign and malignant epithelioid neoplasms.

Clear Cell Change in Reactive Angiogenesis: A Potential Diagnostic Pitfall

Reactive angiogenesis is commonplace, occurs in many circumstances, and is important in the repair of injured tissue. Histologically, it is characterized by newly formed capillaries arranged in a lobular architecture and lined by plump endothelial cells. We have encountered a form of reactive angiogenesis not well described; composed of large endothelial cells with abundant clear cytoplasm that causes diagnostic challenges. The cohort includes 10 patients, aged 4 to 61, mean 40 years; 7 males, 3 females. One case involved bone (ilium), and 9 involved soft tissue: fingers (n=2), toes (n=2), hip joint (n=1), shoulder (n=1), thigh (n=2), and anal mucosa (n=1). Clinically, the patients had chronic ulcers, osteomyelitis, or localized infection. All cases exhibited a lobular proliferation of capillaries lined by large polyhedral endothelial cells that obscured the vessel lumens and were admixed with acute and chronic inflammation. The endothelial nuclei were vesicular with small nucleoli and the cytoplasm was abundant and clear or palely eosinophilic. The endothelial cells were stained with CD31 and ERG (7/7 cases), CD34 (6/6), FLI1 (4/4), and were negative for keratin and CD68 (6/6). Periodic acid-Schiff stain and periodic acid-Schiff stain-diastase on 3 cases did not demonstrate glycogen. Using a polymerase chain reaction, no Bartonella henselae was found in all 6 cases tested. Reactive angiogenesis with clear cell change unassociated with Bartonella spp. has not been described. It causes diagnostic challenges and the differential diagnosis includes benign and malignant tumors, as well as unusual infections. It is important to distinguish between these possibilities because of the significant impact on treatment and prognosis.

Identification of EWSR1-NFATC2 fusion in simple bone cysts

AIMS

Simple bone cysts are benign intramedullary tumours primarily involving the long bones in skeletally immature individuals. Several mechanisms have been proposed for their pathogenesis. Although the diagnosis is typically straightforward, the interpretation can be problematic, because of superimposed fracture causing them to resemble aneurysmal bone cysts and other tumours. EWSR1-NFATC2 or FUS-NFATC2 fusions, which are characteristic of a subset of aggressive round cell sarcomas, have been recently detected in simple bone cysts. The aim of this study was to examine the clinicopathological and molecular features in a series of simple bone cysts.

METHODS AND RESULTS

Using RNA-based next-generation sequencing and/or fluorescence in-situ hybridisation, we investigated the presence of EWSR1 or FUS rearrangements in nine simple bone cysts. The patients were five females and four males, aged 3-23 years (median, 14 years); the tumours ranged from 19 mm to 160 mm (median, 46 mm) in size, and involved the femur (n = 3), humerus (n = 2), fibula (n = 2), tibia (n = 1), and iliac wing (n =1). We identified three cases with EWSR1-NFATC2 fusion (showing identical breakpoints to those in EWSR1-NFATC2 sarcomas) and one additional case with FUS rearrangement. Unlike in EWSR1-NFATC2 sarcomas, immunohistochemical expression of NKX3.1 and NKX2.2 was absent in two simple bone cysts tested.

CONCLUSIONS

More than 40% of simple bone cysts harbour genetic alterations confirming that they are neoplastic, investigation of EWSR1 and/or FUS rearrangement may help to distinguish simple bone cysts from mimics, and NFATC2 rearrangement is not pathognomonic of malignancy.

Primary Sarcomas of the Larynx: A Clinicopathologic Study of 27 Cases

Primary sarcomas of the larynx are rare and are associated with diagnostic and treatment challenges. Studies of these tumors are limited, and most examples have been reported as small series. To further increase our understanding of laryngeal sarcomas, we reviewed our experience of an adult cohort. A retrospective search for laryngeal sarcomas from our pathology archives and consultation files of one of the authors was performed. We studied 27 primary laryngeal sarcomas that included 25 males, and 2 females, with a mean age of 60 years (range 33-85). The cases included conventional chondrosarcoma (16), well-differentiated liposarcoma (2), clear cell chondrosarcoma (1), leiomyosarcoma (2), high grade myxofibrosarcoma (2), high grade myofibroblastic sarcoma (1), low-grade myofibroblastic sarcoma (1), malignant granular cell tumor (1), and Kaposi sarcoma (1). Data on treatment and follow-up was available in 17 and 16 cases, respectively. 12 patients underwent partial laryngeal resection; five had total laryngectomy, and the patient with Kaposi sarcoma received combined highly active antiretroviral therapy and chemotherapy. Three patients developed local recurrence, and two patients developed metastases. The remaining patients with follow up had a favorable outcome and were disease-free after treatment. The important differential diagnosis of spindle cell sarcoma is sarcomatoid squamous cell carcinoma, and their distinction often requires extensive sampling of the mucosal surface and immunohistochemical analysis. The mainstay of treatment for laryngeal sarcomas is surgical removal, with the extent dictated by tumor type and grade. Adjuvant therapy is reserved for high-grade sarcomas and may be given in a neoadjuvant or adjuvant setting.

Amyloidoma: a review and case report

Amyloidoma is a solitary mass of amyloid protein that arises in patients with or without evidence of systemic amyloidosis, and can be found in a variety of different organ systems. Herein, we describe three cases of localized biopsy-positive amyloidomas with no evidence of systemic involvement-primary amyloidoma. Our cases include a patient with a paraspinal soft tissue amyloidoma, a patient with multiple primary amyloidomas involving the thoracic cavity and flank, and a patient with insulin-injection induced amyloidoma of the left shoulder. We present these cases to provide further insights into the clinical presentation of this uncommon clinical entity. We review the pathophysiology of amyloidosis and discuss our cases in the context of previous reports of amyloidoma.

Amyloid Deposition Within a Large Pelvic Chronic Expanding Hematoma

Introduction/Objective

Chronic expanding hematoma (CEH) is a relatively rare complication of trauma that is usually mistaken for a soft tissue neoplasm. The identification of amyloid protein is of paramount clinical importance to exclude serious conditions causing systemic amyloidosis.

Methods

The case was retrieved from the pathology files at the University of Miami Hospital (UMH). Morphology and special stains were reviewed. The study was approved by the Institutional Review Board at UMH.

Results

A 44-year-old man with past history of a stab wound in the left buttock in the 1990s, was admitted with worsening abdominal pain, constipation, urinary obstruction and acute kidney injury. CT-scan showed a large mass involving the left gluteal area and pelvic cavity involving urinary bladder causing outlet obstruction and bilateral hydroureteronephrosis. Multiple radiology-guided biopsies were taken all identifying only fibrin, blood cells, and necrotic inflammatory cells. Excision of the gluteal mass and drainage of the pelvic component was performed confirming the diagnosis of CEH. Amyloid deposition with congo red stain birefringence under polarized light was identified. The patient’s symptoms and renal function improved and have been under follow-up for 1 month.

Conclusion

We have identified amyloid protein deposition whiting a CEH. This is an unusual finding with no previous description found in our search. The identification of amyloid whiting tumor-like lesions is relevant to exclude causes of systemic amyloidosis.

Novel Gene Fusions in Rhabdomyosarcoma

Introduction/Objective

Rhabdomyosarcoma (RMS) encompasses a heterogeneous group of tumors with striated muscle morphology and/or immunophenotype. Molecular analysis of rhabdomyosarcoma has identified a number of aberrations useful for classification. Initially, fusion associated RMS was restricted to tumors with FOXO1 rearrangements, confirming the diagnosis of alveolar RMS, and identifying patients with poor-outcome. Spindle cell RMS, have been described with VGLL2 fusions, EWSR1/FUS-TFCP2 rearrangements, and myoD1 mutations. In addition, NCOA2-MEIS1 fusion gene was recently described in two primary intraosseous RMSs sharing primitive histology. Herein we report two cases of spindle cell RMS, harboring different novel fusion genes, one presenting EP300-VGLL3, and the second with NCOA2-MEIS1 and CAV1-MET.

Methods

Two cases of RMS were retrieved from the pathology files at the University of Miami Hospital (UMH) and Jackson Memorial Hospital (JMH). Morphology and immunohistochemistry were reviewed. A commercial genomic profiling test for both cases was also analyzed. The study was approved by the Institutional Review Board at UMH.

Results

Case #1 is a 36-year-old man presented with a 1.5 cm submucosal mass in the ventral left tongue. The biopsy revealed a malignant spindle cell neoplasm and immunohistochemistry showed tumor cells positive for desmin, SMA, myogenin and MYOD-1. A partial glossectomy was performed, achieving negative resection margins. Next- generation sequencing (NGS) identified an EP300-VGLL3 fusion. The patient is currently being followed and has been disease-free for 6 months. Case #2 is a 19-years-old male with no medical history admitted with lower extremities weakness and a large expansile pelvic bone lesion and multiple spinal metastases. Biopsy from the pelvic lesion revealed malignant primitive round cells and short spindle cells arranged in fascicles which were positive for desmin, MYOD-1, TLE-1 and CD99 and focally positive for myogenin and WT-1. NGS identified two fusion genes, NCOA2- MEIS1 and CAV1-MET.

Conclusion

Different types of rhabdomyosarcoma are associated with a variety of different gene fusions and some may be of prognostic significance. Our two cases are the first reported with EP300-VGLL3 and CAV1-MET fusion genes. CAV1-MET oncogenic potential has been described only in lung cancer. The prognostic significance of rhabdomyosarcoma with novel gene fusions requires longer follow-up and the identification of additional cases.

Dysplastic lipoma: potential diagnostic pitfall of using MDM2 RNA in situ hybridization to distinguish between lipoma and atypical lipomatous tumor

The distinction between lipoma and atypical lipomatous tumor can be challenging in some cases. While detection of MDM2 gene amplification via fluorescence in situ hybridization (FISH) has been well established as a diagnostic tool to distinguish atypical lipomatous tumor and well-differentiated liposarcoma from benign mimics, MDM2 RNA in situ hybridization (RNA-ISH) has recently been proposed as an alternative diagnostic assay. During clinical workup for lipomatous tumors using MDM2 RNA-ISH, we noticed several dysplastic lipomas that were positive for MDM2 RNA-ISH but negative for MDM2 amplification by FISH. In this study, we examined a series of 11 dysplastic lipomas, all confirmed to be negative for MDM2 amplification by FISH. Positive MDM2 RNA-ISH was noted in 10 (91%) dysplastic lipomas. Single-nucleotide polymorphism array on one dysplastic lipoma identified the presence of homozygous deletion of 13q, including the RB1 gene locus with no evidence of MDM2 copy number gain. Our findings on the discordance between MDM2 FISH and MDM2 RNA-ISH highlight the potential utility and pitfalls of using MDM2 RNA-ISH in the distinction of atypical lipomatous tumor and related liposarcomas from dysplastic lipoma.

Synovial Sarcoma of the Nerve-Clinical and Pathological Features: Case Series and Systematic Review

BACKGROUND

Synovial sarcoma of the nerve is a rare entity with several cases and case series reported in the literature. Despite an improved understanding of the biology, the clinical course is difficult to predict.

OBJECTIVE

To compile a series of patients with synovial sarcoma of the peripheral nerve (SSPN) and assess clinical and pathological factors and their contribution to survival and recurrence.

METHODS

Cases from 2 institutions collected in patients undergoing surgical intervention for SSPN. Systematic review including PubMed and Scopus databases were searched for related articles published from 1970 to December 2018. Eligibility criteria: (1) case reports or case series reporting on SSPN, (2) clinical course and/or pathological features of the tumor reported, and (3) articles published in English.

RESULTS

From patients treated at our institutions (13) the average follow-up period was 3.2 yr. Tumor recurrence was seen in 4 cases and death in 3. Systematic review of the literature yielded 44 additional cases with an average follow-up period of 3.6 yr. From pooled data, there were 10 recurrences and 7 deaths (20% and 14%, respectively). Adjuvant treatment used in 62.5% of cases. Immunohistochemical markers used in diagnosis varied widely; the most common are the following: Epithelial membrane antigen (EMA), cytokeratin, vimentin, cluster of differentiation (CD34), and transducin-like enhancer of split 1 (TLE1). Statistical analysis illustrated tumor size and use of chemotherapy to be negative predictors of survival. No other factors, clinically or from pathologist review, were correlated with recurrence or survival.

CONCLUSION

By combining cases from our institution with historical data and performing statistical analysis we show correlation between tumor size and death.

Primary gastrointestinal liposarcoma-a clinicopathological study of 8 cases of a rare entity

Primary gastrointestinal liposarcoma is rare, and information regarding this entity is largely based on single case studies. We report on 8 patients with primary liposarcoma of the gastrointestinal tract and review the pertinent literature. The cohort includes 6 men and 2 women who ranged in age from 51 to 81 years (median 68.5). Two tumors arose in the stomach, 4 in the small intestine, and 2 in the large intestine. Tumors ranged in size from 2.5 to 14.5 cm (median 7 cm), originated in the submucosa or muscularis propria of the intestinal wall, and frequently protruded into the bowel lumen, resulting in mucosal ulceration and luminal obstruction. Six tumors were dedifferentiated liposarcomas, and 2 were well-differentiated liposarcoma. Surgical excision was performed on all tumors except for 1 case of dedifferentiated liposarcoma. On follow-up, 1 patient with dedifferentiated liposarcoma developed a lytic sacral lesion suspicious for metastasis 4 months after resection of the primary, and another underwent marginal resection and presented with recurrence 4 years later, had tumor re-resection, and was considered disease-free at 6 weeks postsurgery. A third patient with dedifferentiated liposarcoma was alive with unknown disease status at 17 months following surgery, and another patient with dedifferentiated liposarcoma was alive without evidence of disease at 30 months following surgery. No follow-up information on the remaining patients is available. Overall, liposarcomas of the intestinal tract are most frequently high-grade dedifferentiated tumors that are biologically aggressive and require surgical excision with widely negative margins to help reduce the risk of local recurrence and dissemination. Important in the differential diagnosis is malignant gastrointestinal stromal tumor. Care must be taken not to misdiagnose one entity for the other because the correct diagnosis carries important therapeutic implications.

Correction to: Angiosarcoma patients treated with immune checkpoint inhibitors: a case series of seven patients from a single institution

Following publication of the original article [1], the authors have reported that the following sentence "While of the same IgG1 class as ipilimumab, preclinical data suggests this molecule may have enhanced activity against T regulatory cells".

Angiosarcoma patients treated with immune checkpoint inhibitors: a case series of seven patients from a single institution

BACKGROUND

Angiosarcoma is an uncommon endothelial malignancy and a highly aggressive soft tissue sarcoma. Due to its infiltrative nature, successful management of localized angiosarcoma is often challenging. Systemic chemotherapy is used in the metastatic setting and occasionally in patients with high-risk localized disease in neoadjuvant or adjuvant settings. However, responses tend to be short-lived and most patients succumb to metastatic disease. Novel therapies are needed for patients with angiosarcomas.

METHODS

We performed a retrospective analysis of patients with locally advanced or metastatic angiosarcoma, who were treated with checkpoint inhibitors at our institution. We collected their clinical information and outcome measurements. In one patient with achieved complete response, we analyzed circulating and infiltrating T cells within peripheral blood and tumor tissue.

RESULTS

We have treated seven angiosarcoma (AS) patients with checkpoint inhibitors either in the context of clinical trials or off label [Pembrolizumab + Axitinib (NCT02636725; n = 1), AGEN1884, a CTLA-4 inhibitor (NCT02694822; n = 2), Pembrolizumab (n = 4)]. Five patients had cutaneous angiosarcoma, one primary breast angiosarcoma and one radiation-associated breast angiosarcoma. At 12 weeks, 5/7 patients (71%) had partial response of their lesions either on imaging and/or clinical exam and two (29%) had progressive disease. 6/7 patients are alive to date and, thus far, 3/7 patients (43%) have progressed (median 3.4 months)- one achieved partial response after pembrolizumab was switched to ongoing Nivolumab/Ipilimumab, one died of progressive disease at 31 weeks (primary breast angiosarcoma) and one was placed on pazopanib. One patient had a complete response (CR) following extended treatment with monotherapy AGEN1884. No patient experienced any ≥ grade 2 toxicities.

CONCLUSIONS

This case series underscores the value of targeted immunotherapy in treating angiosarcoma. It also identifies genetic heterogeneity of cutaneous angiosarcomas and discusses specific genetic findings that may explain reported benefits from immunotherapy.

Epithelioid Hemangioendothelioma of the Bowel in Crohn's Disease: The First Reported Case

BACKGROUND

Epithelioid hemangioendothelioma (EHE) is an uncommon malignant endothelial neoplasm that most commonly arises in soft tissue, bone, lung, and liver. Crohn's disease (CD) is an inflammatory bowel disease of unknown etiology that is frequently associated with complications including strictures, fistulas/fissures, and neoplasms.

CASE DESCRIPTION

A 43-year-old woman with a 6-year history of severe CD presented with anal pain and bleeding. She had prior partial colectomy for a stricture and a diverting ileostomy for perianal fissures and stricture. Colonoscopy showed severe chronic active colitis, stricture at 30 cm of anal verge, and a perianal fistula. The patient underwent total proctocolectomy. The colonic mucosa exhibited segmental ulceration and irregular thickening of the colon wall. Beneath an ulcer of the anal canal within the muscularis propria was a 1.2-cm poorly circumscribed, firm, white-tan mass. The mass was composed of cords and groups of large epithelioid endothelial cells with intracytoplasmic vacuoles enmeshed in a myxohyaline stroma. Immunohistochemically, the tumor cells were positive for ERG, CD31, and CAMTA1 and focally positive for keratin and SMA. Next-generation sequencing revealed a WWTR1-CMATA1 fusion. The morphology, immunoprofile, and molecular genetics were diagnostic of EHE.

DISCUSSION

Long-standing inflammatory bowel disease is associated with significant risk for developing neoplasms, usually carcinomas, which can be indistinguishable radiologically and clinically from nonneoplastic complications. These tumors are often identified as an incidental finding in specimens resected for clinically severe disease. This is the first report of EHE arising in the bowel affected by CD, and it mimicked mural fibrosis and fissures.

Genetic profiling of a chondroblastoma-like osteosarcoma/malignant phosphaturic mesenchymal tumor of bone reveals a homozygous deletion of CDKN2A, intragenic deletion of DMD, and a targetable FN1-FGFR1 gene fusion

Conventional osteosarcoma is the most common primary malignancy of bone. This group of neoplasms is subclassified according to specific histological features, but hitherto there has been no correlation between subtype, treatment, and prognosis. By in-depth genetic analyses of a chondroblastoma-like osteosarcoma, we detect a genetic profile that is distinct from those previously reported in benign and malignant bone tumors. The overall genomic copy number profile was less complex than that typically associated with conventional osteosarcoma, and there was no activating point mutation in any of H3F3A, H3F3B, IDH1, IDH2, BRAF, or GNAS. Instead, we found a homozygous CDKN2A deletion, a DMD microdeletion and an FN1-FGFR1 gene fusion. The latter alteration has been described in phosphaturic mesenchymal tumor. This tumor type shares some morphological features with chondroblastoma-like osteosarcoma and we cannot rule out that the present case actually represents an FN1-FGFR1 positive malignant phosphaturic mesenchymal tumor of bone without osteomalacia.

EWSR1/FUS-NFATc2 rearranged round cell sarcoma: clinicopathological series of 4 cases and literature review

The classification of bone neoplasms composed of small round cells is experiencing a transformation after the discovery of various gene fusion rearrangements that determine diagnosis, behavior, and response to therapy. We present herein 4 new cases of small round cell tumor of the bone that harbor NFATc2 rearrangements involving either EWSR1 or FUS genes. We studied the clinical presentation, pathologic features, genetics (FISH, targeted RNA sequencing) and outcome in these 4 patients. We also reviewed the literature describing similar cases. All our patients were male. The median age at diagnosis was 33.5 years. All tumors presented in long bones of the extremities as a large destructive mass with a mean size of 12.5 cm. All cases were hypercellular with prominent collagenous stroma and consisted of small to medium size round cells arranged in cords, thin trabeculae, and pseudoacinar structures. Most cases showed focal or diffuse membrane staining for CD99; whereas S100, synaptophysin and chromogranin were negative. EMA showed cytoplasmic staining in one case. Genetic studies identified EWSR1-NFATc2 fusion in 3 cases, and FUS-NFATc2 fusion in one case. Two patients were treated with neoadjuvant chemotherapy using Ewing sarcoma regimens, and surgical excision was performed on 3 patients; necrosis was minimal. Follow-up is limited; after a median follow-up of 8.7 months, one patient developed local recurrence and metastases to the lungs. Poorly differentiated round cell sarcoma with EWSR1/FUS-NFATc2 fusions are uncommon. The tumors have consistent clinical findings, morphology, and immunoprofile that in combination are distinctive and differ from that of Ewing sarcoma. Importantly, these tumors do not respond to Ewing sarcoma chemotherapy regimens.

Axitinib plus pembrolizumab in patients with advanced sarcomas including alveolar soft-part sarcoma: a single-centre, single-arm, phase 2 trial

BACKGROUND

VEGF promotes an immunosuppressive microenvironment and contributes to immune checkpoint inhibitor resistance in cancer. We aimed to assess the activity of the VEGF receptor tyrosine-kinase inhibitor axitinib plus the anti-PD-1 immune checkpoint inhibitor pembrolizumab in patients with sarcoma.

METHODS

This single-centre, single-arm, phase 2 trial was undertaken at a tertiary care academic medical centre in Miami, FL, USA, and participants were recruited from all over the USA and internationally. Patients were eligible if they were aged 16 years or older, and had histologically confirmed advanced or metastatic sarcomas, including alveolar soft-part sarcoma (ASPS); measurable disease with one site amenable to repeated biopsies; an ECOG performance status of 0-1; and progressive disease after previous treatment with at least one line of systemic therapy (unless no standard treatment existed or the patient declined therapy). The first five patients were enrolled in a lead-in cohort and were given axitinib 5 mg orally twice daily and pembrolizumab 200 mg intravenously for 30 min on day 8 and every 3 weeks for cycles of 6 weeks for up to 2 years. Thereafter, patients received escalating doses of axitinib (2-10 mg) plus flat dose pembrolizumab according to the schedule above. The primary endpoint was 3-month progression-free survival. All patients were evaluable for survival and safety analyses. This study is registered with ClinicalTrials.gov, number NCT02636725, and is closed to accrual.

FINDINGS

Between April 19, 2016, and Feb 7, 2018, of 36 patients assessed for eligibility, 33 (92%) were enrolled and given study treatment (intention-to-treat population and safety population), 12 (36%) of whom had ASPS. With a median follow-up of 14·7 months (IQR 10·1-19·1), 3-month progression-free survival for all evaluable patients was 65·6% (95% CI 46·6-79·3). For patients with ASPS, 3-month progression-free survival was 72·7% (95% CI 37·1-90·3). The most common grade 3 or 4 treatment-related adverse events included hypertension (five [15%] of 33 patients), autoimmune toxicities (five [15%]), nausea or vomiting (two [6%]), and seizures (two [6%]). Serious treatment-related adverse events occurred in seven (21%) patients, including autoimmune colitis, transaminitis, pneumothorax, haemoptysis, seizures, and hypertriglyceridemia. There were no treatment-related deaths.

INTERPRETATION

Axitinib plus pembrolizumab has manageable toxicity and preliminary activity in patients with advanced sarcomas, particularly patients with ASPS, warranting further investigation in randomised controlled trials.

FUNDING

Merck, Pfizer, American Cancer Society, and Sylvester Comprehensive Cancer Center.

Epithelioid Hemangioendothelioma Arising Within Mediastinal Myelolipoma: A WWTR1-Driven Composite Neoplasm

In this article, we describe a case of conventional epithelioid hemangioendothelioma (EHE) arising within an extra-adrenal myelolipoma. This composite neoplasm arose in the mediastinum of a 51-year-old female. The tumor was composed of a large myelolipoma that contained nodules of EHE consisting of CD31-positive epithelioid endothelial cells that grew in solid cords and were enmeshed in a basophilic hyalinized stroma. Both EHE and myelolipoma are characterized genetically by alterations of WWTR1. We demonstrated the expression of CAMTA-1 chimeric protein by immunohistochemistry both in the neoplastic endothelial cells of EHE and some of the endothelial cells lining the blood vessels in the myelolipoma. To the best of our knowledge, this is the first report of a malignant vascular neoplasm arising in association with myelolipoma.

Myoepithelial carcinoma or epithelioid sarcoma - A rare diagnosis with poor prognosis. A case report and review of literature

INTRODUCTION

Myoepithelial carcinoma and proximal-type epithelioid sarcoma of the vulva are two rare malignancies with known aggressive behavior. In addition to a similar clinical course, these two disease entities also have significant histologic and pathologic overlap. Given the rarity of these malignancies, there is limited literature on the appropriate treatment regimen. Nevertheless, there is a consensus that early surgical resection is beneficial in both cases.

PRESENTATION

We present a case of a patient who was initially diagnosed with myoepithelial carcinoma of the vulva with a differential later expanded to include possible epithelioid sarcoma.

DISCUSSION

We demonstrate the importance in early identification of a SMARCB1 deficiency. Additionally, we suggest an appropriate treatment regimen for these patients going forward. Specifically, we encourage consideration of bilateral superficial and deep inguinal lymphadenectomies. Furthermore, sarcoma based chemotherapy regimens in the appropriate clinical setting may be beneficial in treating SMARCB1 deficient tumors. Additionally, there are now clinical trials involving EZH2 Inhibitors which may offer benefit for similar patients going forward.

CONCLUSION

This case highlights the difficulty in making a definitive diagnosis, and the importance in identifying a SMARCB1 deficiency as it will affect treatment options and may allow for enrollment in ongoing clinical trials.