Genetic diversity in alveolar soft part sarcoma: A subset contain variant fusion genes, highlighting broader molecular kinship with other MiT family tumors

Establishment and characterization of NCC-ASPS2-C1: a novel patient-derived cell line of alveolar soft part sarcoma

Alveolar soft part sarcoma (ASPS) is a rare mesenchymal tumor characterized by rearrangement of the ASPSCR1 and TFE3 genes and a histologically distinctive pseudoalveolar pattern. ASPS progresses slowly, but is prone to late metastasis. As ASPS is refractory to conventional chemotherapy, the only curative treatment is complete surgical resection. The prognosis of advanced and metastatic cases is poor, highlighting the need for preclinical research to develop appropriate treatment options. However, ASPS is extremely rare, accounting for < 1% of all soft tissue sarcomas, and only one patient-derived ASPS cell line is available from public cell banks worldwide for research. This study reports the establishment of a novel ASPS cell line derived from the primary tumor tissue of an ASPS patient, named NCC-ASPS2-C1. This cell line retains the ASPSCR1-TFE3 fusion gene, which is characteristic of ASPS. The characterization of this cell line revealed stable growth, spheroid formation, and invasive properties. By screening a drug library using NCC-ASPS2-C1, we identified several drugs that inhibited the proliferation of ASPS cells. In conclusion, the establishment of NCC-ASPS2-C1 provides a valuable resource for advancing ASPS research and developing novel treatments for this challenging disease.

An unusual case of primary splenic soft part alveolar sarcoma: case report and review of the literature with emphasis on the spectrum of TFE3-associated neoplasms

BACKGROUND

Alveolar soft part sarcoma is a rare tumour of soft tissues, mostly localized in muscles or deep soft tissues of the extremities. In rare occasions, this tumour develops in deep tissues of the abdomen or pelvis.

CASE PRESENTATION

In this case report, we described the case of a 46 year old man who developed a primary splenic alveolar soft part sarcoma. The tumour displayed typical morphological alveolar aspect, as well as immunohistochemical profile notably TFE3 nuclear staining. Detection of ASPSCR1 Exon 7::TFE3 Exon 6 fusion transcript in molecular biology and TFE3 rearrangement in FISH confirmed the diagnosis.

CONCLUSION

We described the first case of primary splenic alveolar soft part sarcoma, which questions once again the cell of origin of this rare tumour.

PEComa with ASPSCR1::TFE3 fusion: expanding the molecular genetic spectrum of TFE3-rearranged PEComa with an emphasis on overlap with alveolar soft part sarcoma

AIMS

Mesenchymal neoplasms involving TFE3 gene fusions are diverse, mainly include alveolar soft part sarcoma (ASPS) that is characterised by ASPSCR1::TFE3 fusion, and a small subset of perivascular epithelioid cell tumours (PEComas) referred to as TFE3-rearranged PEComa, that most frequently harbours SFPQ::TFE3 fusion. Historically, ASPS and TFE3-rearranged PEComa are considered two distinctive entities despite their known morphological overlap. However, recent studies have suggested a potential histogenetic relationship between them, and several neoplasms that showed morphological features more closely fit PEComa rather than ASPS but harboured ASPSCR1::TFE3 fusion have been documented. In this study, we report three cases of PEComa with ASPSCR1::TFE3 fusion.

METHODS AND RESULTS

Clinicopathological features were assessed and partner agnostic targeted next-generation sequencing on clinically validated platforms were performed. The patients are two females and one male with age at presentation ranging from 21 to 51 years. All three tumours were located in the viscera (rectum, kidney and cervix). On a relatively limited follow-up period (range = 9-15 months), all patients are alive without evidence of recurrent or metastatic disease. The neoplasms were composed of tight nested architecture of epithelioid clear cells separated by a delicate vascular network, two of which were associated with sheets of plump spindle cells, and none showed significant discohesive tumour morphology. Immunohistochemically, in addition to TFE3 protein, all three neoplasms demonstrated co-expression of melan-A and smooth muscle actin. RNA-sequencing identified ASPSCR1::TFE3 fusion in all three cases that were confirmed by subsequent fluorescence in-situ hybridisation analyses.

CONCLUSIONS

Our study expands the molecular genetic spectrum of TFE3-rearranged PEComa and further indicates its close relationship to ASPS.

Alveolar Soft Part Sarcoma in the Female Genital Tract: Case Series with Literature Review and SEER Database Analysis

Introduction

Alveolar soft part sarcoma (ASPS) is a rare and distinct subtype of soft tissue sarcoma. This study aims to describe the unique presentation of ASPS in the female genital tract.

Methods

Prognostic factors for cancer-specific overall survival (CSS) were evaluated using multivariate analyses.

Results

In our case series, we identified a novel TFE3-PRCC gene fusion in a 24-year-old unmarried patient with cervical ASPS who underwent fertility-sparing surgery and remained recurrence-free for 41 months. The other two patients underwent radical hysterectomy and bilateral salpingo-oophorectomy. At the time of writing, the two patients had been disease-free for 49 and 71 months, fluorescence in situ hybridization showed break-apart signals for the ASPL-TFE3 gene. Among the 55 cases with available information from the PubMed/Medline database, most presented with localized disease, and at the last follow-up, all patients were alive and 45 patients showed no evidence of disease. The 5-year CSS rate in the female genital tract cohort from SEER database was 86.2%. Multivariate analysis revealed that older age was associated with a 1.042-fold increased risk of cancer-specific mortality (HR=1.042, 95% CI 1.022-1.063, P < 0.001), involvement of soft tissue including the heart was associated with a 4.786-fold higher risk (HR=4.7868, 95% CI 1.681-13.623, P= 0.003), and regional infiltration and distant metastasis were associated with approximately 8.6-fold and 18-fold higher risk of cancer-specific mortality compared to local disease, respectively (HR=8.652, 95% CI 2.529-29.63, P = 0.001; HR=18.366, 95% CI 6.153-54.817, P< 0.001). Patients who underwent radical excision did not show reduced cancer-specific mortality compared to those who underwent local excision (HR=0.492, 95% CI 0.224-1.081, P = 0.078).

Discussion

Previously unrecognized genetic diversity exists in ASPS. Patients with ASPS in the female genital tract have the lowest likelihood of presenting with a distant disease and are associated with a more favorable survival outcome.

Clinico-Pathological Spectrum of Alveolar Soft Part Sarcoma: Case Series from a Tertiary Care Cancer Referral Centre in India with a Focus on Unusual Clinical and Histological Features

OBJECTIVE

Alveolar soft part sarcoma (ASPS) is characterized by distinctive histomorphology of variably discohesive epithelioid cells arranged in nests and translocation of t(x;17) (p11.2;q25) resulting in ASPSCR1-TFE3 fusion. The aim of the present study is to review the clinical, histopathological, and immunohistochemical profile of ASPS with a focus on unusual histological features.

MATERIAL AND METHOD

The present study is retrospective and descriptive. All cases with a diagnosis of ASPS were retrieved with clinical and radiology details.

RESULTS

22 patients of ASPS were identified. The most common site was the lower extremity and the size range was 3-22 cm. 54.5% of the patients had metastasis, with the lung as the most common site. Metastasis preceded detection of primary tumour in two cases. All cases showed similar histopathology of monomorphic epithelioid cells arranged in nests encircled by sinusoidal vasculature. Architecturally, the organoid pattern (81.8%) was followed by the alveolar pattern. 68.2% of the cases showed apple bite nuclei as the predominant nuclear feature. Rare nuclear features included binucleation (n=13), multinucleation (n=8), pleomorphism (n=4), nuclear grooves in three cases and intranuclear inclusion in one case, mitosis (n=5), and focal necrosis (n=6). All cases were positive for TFE3 and negative for AE1/AE3, EMA, HMB45, PAX8, MyoD1, SMA, synaptophysin, and chromogranin. Only two cases showed focal S100 positivity while one showed focal desmin positivity.

CONCLUSION

Diffuse strong nuclear TFE3 positivity is sensitive for ASPS in an appropriate clinicoradiological context. Due to the high propensity for early metastasis, complete metastatic work-up and long term follow up is recommended.

Advances in treatment of alveolar soft part sarcoma: an updated review

Alveolar soft part sarcoma is a rare neoplasm of uncertain histogenesis that belongs to a newly defined category of ultra-rare sarcomas. The neoplasm is characterized by a specific chromosomal translocation, der (17) t(X; 17)(p11.2;q25), that results in ASPSCR1-TFE3 gene fusion. The natural history of alveolar soft part sarcoma describes indolent behaviour with slow progression in deep soft tissues of the extremities, trunk and head/neck in adolescents and young adults. A high rate of detection of distant metastasis at presentation has been reported, and the most common metastatic sites in decreasing order of frequency are the lung, bone and brain. Complete surgical resection remains the standard treatment strategy, whereas radiotherapy is indicated for patients with inadequate surgical margins or unresectable tumours. Although alveolar soft part sarcoma is refractory to conventional doxorubicin-based chemotherapy, monotherapy or combination therapy using tyrosine kinase inhibitors and immune checkpoint inhibitors have provided antitumor activity and emerged as new treatment strategies. This article provides an overview of the current understanding of this ultra-rare sarcoma and recent advancements in treatments according to the clinical stage of alveolar soft part sarcoma.

Alveolar soft part sarcoma of the uterine corpus: A 13-year follow-up case report and review of the literature

OBJECTIVE

Female genital alveolar soft part sarcoma (ASPS) is rare and has a favourable prognosis compared to ASPS from other sites. We reported our experience to manage a case with uterine corpus ASPS (UC ASPS) and conducted a literature review on prognosis of ASPS from different sites of female genital tract.

CASE REPORT

This report represented a 33-year-old woman who had UC ASPS. She received tumor excision with uterine preservation and had the longest follow-up time (155 months) without recurrence in the literature.

CONCLUSION

UC ASPS has better prognosis than ASPS from the uterine cervix, the low uterine segment, vulvovaginal area and perineum. We recommended conservative treatment for young women with UC ASPS.

The HNRNPF/H RNA binding proteins and disease

The members of the HNRNPF/H family of heterogeneous nuclear RNA proteins-HNRNPF, HNRNPH1, HNRNPH2, HNRNPH3, and GRSF1, are critical regulators of RNA maturation. Documented functions of these proteins include regulating splicing, particularly alternative splicing, 5' capping and 3' polyadenylation of RNAs, and RNA export. The assignment of these proteins to the HNRNPF/H protein family members relates to differences in the amino acid composition of their RNA recognition motifs, which differ from those of other RNA binding proteins (RBPs). HNRNPF/H proteins typically bind RNA sequences enriched with guanine (G) residues, including sequences that, in the presence of a cation, have the potential to form higher-order G-quadruplex structures. The need to further investigate members of the HNRNPF/H family of RBPs has intensified with the recent descriptions of their involvement in several disease states, including the pediatric tumor Ewing sarcoma and the hematological malignancy mantle cell lymphoma; newly described groups of developmental syndromes; and neuronal-related disorders, including addictive behavior. Here, to foster the study of the HNRNPF/H family of RBPs, we discuss features of the genes encoding these proteins, their structures and functions, and emerging contributions to disease. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Processing > Splicing Regulation/Alternative Splicing RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.

Lingual Alveolar Soft Part Sarcoma in a 78-Year-Old Woman: A Case Report and Comprehensive Review of the Literature from 1952 to 2022

BACKGROUND

Alveolar soft part sarcoma (ASPS) is a rare translocation-related soft tissue sarcoma, occurring mainly in the limbs and trunk in young adults and adolescents. ASPS is rarely seen in the head and neck and one fourth of those cases described are tongue primary. Given its nonspecific symptoms, clinical findings, and rarity in this location, lingual ASPS (L-ASPS) has been reported to be commonly misdiagnosed as various benign tumors, leading to adverse outcomes.

METHODS

We report a case of L-ASPS occurring in the oldest (78 years) female patient published to date and comprehensively review the literature from 1952 to 2022.

RESULTS

She presented with a slow-growing (2-year duration) tongue mass, measuring 3.5 cm on palpation. Intraoperative frozen section could not render the definitive diagnosis. The pathological findings of the tumor were characteristic of ASPS with eosinophilic polygonal cells in an organoid/nested pattern, rich sinusoidal capillaries, and TFE3 immunoreactivity, except for the strong diffuse aberrant cytoplasmic CD68 immunoexpression and absence of intracytoplasmic crystalline inclusions on PAS with diastase. After TFE3 gene rearrangement had been identified with fluorescent in-situ hybridization, reflex testing confirmed a rearrangement of TFE3 gene with the known fusion partner ASPSCR1.

CONCLUSIONS

ASPS should be included in the differential diagnoses in cases of any slow-growing lingual masses (especially vascular ones) with non-specific clinical pictures, regardless of the patient's age.

PEComa-like Neoplasms Characterized by ASPSCR1-TFE3 Fusion: Another Face of TFE3-related Mesenchymal Neoplasia

Identical TFE3-related gene fusions may be found in renal cell carcinoma and mesenchymal neoplasms such as alveolar soft part sarcoma and TFE3-rearranged perivascular epithelioid cell tumor (PEComa). Among mesenchymal neoplasms, the ASPSCR1-TFE3 gene fusion has previously been described only in alveolar soft part sarcoma. We report 3 unusual mesenchymal neoplasms harboring the ASPSCR1-TFE3 gene fusion, the morphologic phenotype of which more closely matches PEComa rather than alveolar soft part sarcoma. All 3 neoplasms occurred in females ranging in age from 18 to 34 years and were located in the viscera (kidney, bladder, and uterus). All 3 contained nests of epithelioid cells bounded by fibrovascular septa. However, all were associated with hyalinized stroma, tight nested architecture, mixed spindle cell and epithelioid pattern, clear cytoplasm, and lacked significant discohesion. Overall, morphologic features closely resembled PEComa, being distinct from the typical alveolar soft part sarcoma phenotype. While none of the neoplasms labeled for HMB45, cytokeratin, or PAX8 all showed positivity for TFE3 and cathepsin K, and all except 1 were positive for smooth muscle actin. One patient developed a liver metastasis 7 years after nephrectomy. These cases bridge the gap between 2 TFE3-rearranged neoplasms, specifically alveolar soft part sarcoma and Xp11 translocation PEComa, highlighting the relatedness and overlap among Xp11 translocation neoplasms. While most TFE3-rearranged neoplasms can be confidently placed into a specific diagnostic category such as alveolar soft part sarcoma, PEComa, or Xp11 translocation renal cell carcinoma, occasional cases have overlapping features, highlighting the potential role that the cell of origin and the specific gene fusion play in the phenotype of these neoplasms.

Epstein-Barr Virus-Associated Smooth Muscle Tumors of Larynx: A Clinicopathologic Study and Comprehensive Literature Review of 12 Cases

Laryngeal mesenchymal neoplasms are rare, with smooth muscle tumors comprising a small subset. Specifically, Epstein-Barr virus (EBV)-associated smooth muscle tumors are exceptionally rare, lacking a comprehensive evaluation of their clinical and histologic features. Two patients (a 59 year old male and 51 year old female) had received renal transplants 156 and 240 months, respectively prior to onset of laryngeal symptoms. Supraglottic polypoid masses were identified and removed conservatively. Histologically, the tumors were hypercellular, showing alternating light and dark areas, the latter composed of primitive appearing round cells, while a more characteristic spindled tumor cell population was noted in the remaining areas. Cytoplasmic vacuoles were noted adjacent to the nucleus. There was no tumor necrosis or pleomorphism, but increased mitotic figures (11-12/2 mm²) were seen, without atypical forms. The tumor cells were strongly immunoreactive with smooth muscle actin and smooth muscle myosin heavy chain and with Epstein-Barr virus encoded RNA (EBER) by in situ hybridization. These patients were reviewed in the context of a thorough English literature review, which demonstrates a wide age range at presentation without a sex predilection, but with most patients from specific ethnic groups (Chinese, Thai, Pilipino). Three-quarters of patients are part of multifocal disease and the majority are post-renal transplantation patients. Conservative management seems to yield the best overall outcome for these indolent tumors. In conclusion, EBV-associated smooth muscle tumors should be considered in any immunocompromised patient with a head and neck smooth muscle tumor, especially when EBER is documented by in situ hybridization. Conservative management may be employed, even when multifocal tumors are documented.

Alveolar soft part sarcoma presenting in an unusual laryngeal location

Alveolar soft part sarcoma (ASPS) is a rare malignant neoplasm that tends to occur in the deep soft tissues of both adults and children. ASPS has a progressive clinical course that is unfortunately characterised by late metastases and an overall poor prognosis. Although the tumour has been reported in a wide range of anatomic sites, few cases of primary laryngeal ASPS are reported in the literature. Here, we report the case of a 24-year-old man with no significant medical history who presented with progressive mild dysphonia and hoarseness. Imaging studies revealed a well-circumscribed, partially cystic submucosal mass with involvement of the right vocal fold and other local structures, and the patient was referred for surgical excision. Morphological and immunohistochemical examination of the excised lesion revealed ASPS. The findings of this case are compared with those of seven additional cases of primary laryngeal ASPS, which were found following literature review.

Alveolar Soft Part Sarcoma of the Oro-Maxillofacial Region in the Pediatric Age Group: Immunohistochemical and Ultrastructural Diagnosis of Two Cases

Alveolar soft part sarcoma (ASPS) is infrequent in children. While head and neck locations, including the orbit and tongue, are described, only six cases of sinonasal ASPS are reported in the literature. We report two cases of pediatric oro-maxillofacial ASPS. The first case presented as a sinonasal mass in a 13-year-old girl, while the second was a tongue lesion in a 4-year-old female. Histologic examination, TFE3 immunopositivity, and ultrastructural findings of rhomboid crystalline inclusions helped confirm the diagnosis. The diagnosis of ASPS is challenging in children and in uncommon sites like the head and neck. Patients should be routinely followed up for detection of residual or recurrent disease, particularly in cases with positive resection margins.

Ocular PEComas are frequently melanotic and TFE3-translocated: report of two cases including the first description of PRCC-TFE3 fusion in PEComa

Ocular perivascular epithelioid cell tumor (PEComa) is exceedingly rare. We reported two examples involving the choroid and subconjunctival tissue, respectively, in patients aged 17 and 20 years. Both tumors comprised packets and sheets of large polygonal cells with moderately pleomorphic nuclei and prominent nucleoli, traversed by delicate fibrovascular septa. Melanin pigmentation was present in one case. The tumors showed HMB45 and TFE3 immunoreactivity. TFE3 gene translocation was confirmed by FISH break-apart probes. RNA seq revealed PRCC-TFE3 and NONO-TFE3 fusions, with the former representing the first description of PRCC-TFE3 in PEComa. Critical reappraisal of the reported cases showed that ocular PEComa frequently affected young patents with melanin pigmentation, frequent TFE3 protein expression, and/or TFE3 gene translocation. No recurrence or metastasis was reported after complete excision despite the presence of cytologic atypia.

Malignant melanotic Xp11 neoplasms exhibit a clinicopathologic spectrum and gene expression profiling akin to alveolar soft part sarcoma: a proposal for reclassification

The classification of the distinct group of mesenchymal neoplasms, first described as 'Xp11 translocation perivascular epithelioid cell tumor (PEComa)' and for which the term 'melanotic Xp11 neoplasm' or 'Xp11 neoplasm with melanocytic differentiation' has recently been proposed, remains challenging and controversial. We collected 27 melanotic Xp11 neoplasms, the largest series to date, for a comprehensive evaluation. Fourteen of the cases, together with eight alveolar soft part sarcomas (ASPS), nine conventional PEComas and a control group of seven normal tissues were submitted to RNA sequencing. Follow-up available in 22 patients showed 5-year overall survival and 5-year disease-free survival of 47.6 and 35.7%, respectively, which were similar to ASPS and significantly worse than conventional PEComa. Univariate analysis of location (occurring in the kidney versus not kidney), infiltrative growth pattern, nuclear pleomorphism, mitotic activity ≥2/50 high-power fields (HPF), necrosis and lymphovascular invasion were found to be associated with overall survival and/or disease-free survival. Multivariate analysis identified that location was the only factor found to independently correlate with disease-free survival. More importantly, RNA sequencing-based clustering analysis segregated melanotic Xp11 neoplasm and ASPS from other tumors, including conventional PEComa and Xp11 translocation renal cell carcinoma, and formed a compact cluster representative of the largely similar expression signature. Here we clearly define the true biologic nature of melanotic Xp11 neoplasms which are distinctive malignant mesenchymal tumors, rather than simply PEComa variants with occasionally unpredictable behavior. Meanwhile, melanotic Xp11 neoplasm and ASPS more likely represent phenotypic variants of the same entity, which is distinct from conventional PEComa and Xp11 translocation renal cell carcinoma. Based on these important findings, melanotic Xp11 neoplasm might be reclassified into a distinctive entity together with ASPS, independent from PEComa, in future revisions of the current WHO categories of tumors of soft tissue and bone for the improved reclassification. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Primary alveolar soft part sarcoma of the rectum resected by endoscopic submucosal dissection: A case report

Alveolar soft part sarcoma (ASPS) is a very rare soft tissue sarcoma. Primary ASPS of the gastrointestinal tract is especially rare. Due to the scarcity of cases, neither its clinicopathologic features nor its mutational background has been clarified. Here, we report a case of ASPS arising from the rectum, which was completely resected by endoscopic submucosal dissection. The lesion was a 17 × 16 × 15 mm semi-pedunculated mass in the upper portion of the rectum in a 46-year-old female. In terms of histology, tumor cells exhibited confluent eosinophilic cytoplasm, forming a sheet-like architecture. Periodic acid Schiff-positive diastase-resistant intracytoplasmic crystals were observed in the tumor cells. Fluorescence in situ hybridization revealed TFE3 rearrangement, and reverse transcription polymerase chain reaction revealed an ASPSCR1-TFE3 type 1 fusion. Negative PAX8 immunostaining and the absence of other massive lesions in postoperative imaging studies led to a diagnosis of primary ASPS of the rectum. The potential oncogenic role of the canonical ASPSCR1-TFE3 fusion transcript in gastrointestinal ASPS was indicated. Primary gastrointestinal ASPS remains a diagnostic pitfall in routine surgical pathology.

Primary Thyroid Gland Alveolar Soft Part Sarcoma

Alveolar soft part sarcoma (ASPS) is a rare soft tissue tumor of unknown histogenesis generally characterized by the der(17)t(X;17)(p11.2;q25) translocation which results in the ASPSCR1-TFE3 gene fusion. Primary ASPS of the thyroid gland has not yet been reported. During oncology follow-up for breast cancer, a pulmonary nodule and thyroid gland mass were identified in a 71-year-old Korean male. Thyroid ultrasound showed a 5.7 cm left thyroid gland mass. After several fine needle aspirations, a thyroid gland lobectomy was performed after documenting only non-caseating granulomatous inflammation in a biopsy of the lung nodule. A 7.6 cm bulging nodular thyroid gland mass was identified, showing significant destructive invasion. Alveolar nests of large polygonal, eosinophilic, granular neoplastic cells were separated by vascularized stroma. Colloid was absent. Tumor necrosis and increased mitoses were identified. The neoplastic cells were positive with TFE3 and CD68, but negative with pancytokeratin, thyroglobulin, TTF-1, napsin-A, calcitonin, PAX8, CAIX, S100 protein, HMB45, SMA, and desmin. FISH confirmed a TFE3 gene rearrangement. The differential includes several primary thyroid gland epithelial neoplasms, paraganglioma, PEComa, melanoma, crystal storage disease, and metastatic carcinomas, especially Xp11 translocation renal cell carcinoma. The patient has refused additional therapy, but is alive without tumor identified (primary or metastatic).