Perivascular epithelioid cell neoplasms of soft tissue and gynecologic origin: a clinicopathologic study of 26 cases and review of the literature

Clinical features of 18 perivascular epithelioid cell tumor cases

To investigate the biological behavior and clinical characteristics of perivascular epithelioid cell tumor (PEComa).Eighteen PEComa patients admitted to Zhongshan Hospital and the Central Hospital of Xuhui District in China from January 2006 to October 2018 were included. All patients were diagnosed based on pathological findings and treated with surgical resection or medication.Among the 18 patients, 1 underwent lymph node biopsy for multiple enlarged lymph nodes and 17 underwent mass resection. The median disease-free survival was 22 months after the first resection and over 12 months following a second resection. Treatment with mechanistic target of rapamycin (mTOR) inhibitors was effective for patients with unresectable or metastatic lesions. The median progression-free survival was approximately 13 months.Surgery is the predominant treatment approach for PEComa and patients can benefit from multiple operations. mTOR inhibitors are considered for patients with multiple lesions or intolerance to surgery. Anti-angiogenetic drugs can be selected when mTOR inhibitors fail to control the illness.

Gene of the month: TFE 3

Transcription factor enhancer 3 (TFE3), on the short arm of chromosome Xp11.23 and its protein, belongs to the microphthalmia transcription family (MiTF) of transcription factors. It shares close homology with another member of the family, MiTF which is involved in melanocyte development. When a cell is stressed and/or starved, TFE3 protein translocates into the nucleus. TFE3 gene fusions with multiple different partner genes occur in several tumours with resultant nuclear expression of TFE3 protein. The main tumours associated with TFE3 gene fusions are: renal cell carcinoma, alveolar soft part sarcoma, a subset of epithelioid haemangioendotheliomas (EHE), some perivascular epithelioid cell tumours and rare examples of ossifying fibromyxoid tumour and malignant chondroid syringoma. TFE3 immunohistochemistry is of use in routine diagnostic practice with the aforementioned tumours harbouring TFE3 fusions leading to nuclear staining. In addition, there are tumours lacking TFE3 fusions but also display TFE3 nuclear immunolabeling, and these include: granular cell tumour, solid pseudopapillary neoplasm of the pancreas and ovarian sclerosing stromal tumour.

Perivascular epithelioid cell tumors (PEComa) of the female genital tract: A challenging question for gynaecologic oncologist and pathologist

Perivascular epithelioid cell tumors (PEComa)s are mesenchymal neoplasms composed of perivascular epithelioid cells, which express both melanocytic and myogenic markers. These neoplastic cells are thought to arise from undifferentiated cells of the neural crest, or from myoblastic cells harbouring a molecular alteration leading to expression of melanocytic markers, or from pericytic cells. The majority of cases are benign, but a small subset behaves in a malignant fashion. Unfortunately, given their rarity, reliable criteria for predicting malignancy have yet to be established. PEComas of the female genital tract account for nearly 25% of PEComas of all body sites, and the most common site of occurrence is the uterine corpus; less common sites include the cervix, adnexa, vagina/vulva or broad or round ligament exceptionally. The present review aims to elucidate the clinical, pathological and molecular features of gynecological PEComas. Moreover, prognostic and therapeutic implications are also discussed.

Medical treatment of advanced malignant perivascular epithelioid cell tumors

PURPOSE OF REVIEW

Malignant PEComa are rare mesenchymal tumors characterized by genetic alterations actionable by target therapy. Indeed, they harbour loss of function of TSC1/TSC2, which lead to the activation of the mammalian target of rapamycin (mTOR) pathway, which is targetable therapeutically with mTOR inhibitors like sirolimus. A small subset of malignant PEComas instead harbor TFE3 gene fusions known to be mutually exclusive with TSC1/TSC2 loss-of-function mutations; therefore, leading to different therapeutic implication.

RECENT FINDINGS

mTOR inhibitors showed a response rate around 40% with a median PFS of 9 months both in retrospective case series than in phase 2 prospective clinical trials, therefore, representing the most active therapeutic drug. Up to now, the issue is the lack of further therapeutic lines in the advanced setting. Chemotherapy has a marginal role, while some responses were reported using Vascular endothelial growth factor-Tyrosine kynase inhibitors (VEGF-TKI) inhibitors.

SUMMARY

Malignant PEComas display some sensitivity to mTOR inhibitors. If progression thereto, no other drugs are available. Preclinical studies are ongoing to explore the potential combination of hormonal blockade in women and the potential use of PD1 checkpoint inhibitors.

A surgical case of primary perivascular epithelioid cell tumor of the heart

BACKGROUND

We encountered an extremely rare case of perivascular epithelioid cell tumor (PEComa) of the heart.

CASE REPORT

A 54-year-old woman was admitted to our hospital because a solid mass developing in the left atrioventricular groove by computed tomography scans of the chest. Histologic examination of the resected tumor revealed that the tumor had proliferating fusiform or spheroid cells with clear cytoplasm. Immunostaining showed positive results for α-smooth muscle actin, a myogenic marker, and human melanin black-45 (HMB-45), leading to a diagnosis of PEComa. The patient was discharged uneventfully, and there was no recurrence for the last thirteen years postoperatively.

CONCLUSIONS

We experienced a surgical case of PEComa primarily occurring in the heart. Although no sign of a recurrence is observed to date, we consider it necessary to follow up the case carefully.

An Algorithmic Immunohistochemical Approach to Define Tumor Type and Assign Site of Origin

Immunohistochemistry represents an indispensable complement to an epidemiology and morphology-driven approach to tumor diagnosis and site of origin assignment. This review reflects the state of my current practice, based on 15-years' experience in Pathology and a deep-dive into the literature, always striving to be better equipped to answer the age old questions, "What is it, and where is it from?" The tables and figures in this manuscript are the ones I "pull up on the computer" when I am teaching at the microscope and turn to myself when I am (frequently) stuck. This field is so exciting because I firmly believe that, through the application of next-generation immunohistochemistry, we can provide better answers than ever before. Specific topics covered in this review include (1) broad tumor classification and associated screening markers; (2) the role of cancer epidemiology in determining pretest probability; (3) broad-spectrum epithelial markers; (4) noncanonical expression of broad tumor class screening markers; (5) a morphologic pattern-based approach to poorly to undifferentiated malignant neoplasms; (6) a morphologic and immunohistochemical approach to define 4 main carcinoma types; (7) CK7/CK20 coordinate expression; (8) added value of semiquantitative immunohistochemical stain assessment; algorithmic immunohistochemical approaches to (9) "garden variety" adenocarcinomas presenting in the liver, (10) large polygonal cell adenocarcinomas, (11) the distinction of primary surface ovarian epithelial tumors with mucinous features from metastasis, (12) tumors presenting at alternative anatomic sites, (13) squamous cell carcinoma versus urothelial carcinoma, and neuroendocrine neoplasms, including (14) the distinction of pheochromocytoma/paraganglioma from well-differentiated neuroendocrine tumor, site of origin assignment in (15) well-differentiated neuroendocrine tumor and (16) poorly differentiated neuroendocrine carcinoma, and (17) the distinction of well-differentiated neuroendocrine tumor G3 from poorly differentiated neuroendocrine carcinoma; it concludes with (18) a discussion of diagnostic considerations in the broad-spectrum keratin/CD45/S-100-"triple-negative" neoplasm.

A Comprehensive Review of Biomarker Use in the Gynecologic Tract Including Differential Diagnoses and Diagnostic Pitfalls

Morphologic (ie, hematoxylin and eosin) evaluation of the Mullerian tract remains the gold standard for diagnostic evaluation; nevertheless, ancillary/biomarker studies are increasingly utilized in daily practice to assist in the subclassification of gynecologic lesions and tumors. The most frequently utilized "biomarker" technique is immunohistochemistry; however, in situ hybridization (chromogenic and fluorescence), chromosomal evaluation, and molecular analysis can also be utilized to aid in diagnosis. This review focuses on the use of immunohistochemistry in the Mullerian tract, and discusses common antibody panels, sensitivity and specificity of specific antibodies, and points out potential diagnostic pitfalls when using such antibodies.

Overview of « druggable » alterations by histological subtypes of sarcomas and connective tissue intermediate malignancies

We summarize herein the literature data about molecular targeted therapies in sarcomas and conjunctive tissue intermediate malignancies. For each clinical setting, the level of evidence, the mechanism of action and the target are described. The two major axes include (i) identification of subgroups of tumors with druggable alteration irrespective of the histological diagnosis (e.g. NTRK), and (ii) druggable target of pathway related to the physiopathology of the tumor: denosumab and bone giant cell tumor, imatinib and soft tissue giant cell tumor, mTOR inhibitor and PECOMA.

Malignant perivascular epithelioid tumor of the vagina: Report of a rare case with brief review of literature

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal tumors with immunohistochemical co-expression of melanocytic and myoid markers. Vaginal PEComas have been described in only nine cases so far. We describe the case of a 65-year-old female with a large growth in the left lateral vaginal wall. Biopsy imprint smears showed dispersed tumor cells with anisonucleosis, multinucleation, and bizarre forms, suggestive of a malignant tumor. Histopathology, however, showed perivascular arrangement of clear epithelioid cells, focal necrosis, intracellular brown pigment in few cells, and mitotic activity at 2 to 3 per 50 high power fields. Immunohistochemical positivity for vimentin, HMB-45, S-100 protein, desmin, and MyoD1 assisted in rendering a final pathological diagnosis of malignant PEComa of the vagina. Further work-up revealed metastatic deposits in liver and retroperitoneal lymph nodes. PEComa arising in vagina is an unusual phenomenon with the malignant variant being an extremely rare tumor. Awareness of the characteristic morphology and utilization of a panel of immunohistochemical stains are mandatory to be able to make a precise diagnosis and appropriate prognostication.

Genomic-guided precision therapy for soft tissue sarcoma

Soft tissue sarcoma (STS), although heterogeneous in histopathology presentation, has mostly been treated with chemotherapy agents as one entity. Our understanding of crucial genomic alterations in different STS histologies and the advent of molecular-targeted agents have reshaped the treatment paradigm for advanced STS. Small-molecule inhibitors of c-KIT, plate-derived growth factor receptor alpha, c-MET, BRAF, anaplastic lymphoma kinase, ROS1 and colony-stimulating factor-1 receptor have been successfully validated in clinical studies to yield practice-changing results. Inhibitors of other novel genomic targets including mouse double minute 2 homolog, cyclin-dependent kinase 4/6, mitogen-activated protein kinase and epigenetic regulators are expected to be developed in the near future. Furthermore, with the advancement and accessibility of molecular diagnosis and next-generation sequencing, a genomic-based therapeutic approach should be widely applicable to advanced STS patients. This review will focus on the progress of genomic-guided therapy tailored to each molecular alteration of different STS histologies.

Perivascular epithelioid cell tumor (PEComa) of the pterygopalatine fossa

Perivascular epithelioid cell tumors (PEComas) are a rare group of mesenchymal tumors associated with tuberous sclerosis. These tumors are typically treated with resection and rarely recur or exhibit malignant behavior. A 78-year-old woman presented with an incidentally discovered pterygopalatine fossa/retroantral mass. Excisional biopsy was performed and revealed pathology consistent with PEComa. Upon review of the literature, there have been 43 reported cases of PEComa of the head and neck. There is only one previously reported case of PEComa in the skull base, and none reported in the pterygopalatine fossa. Of note, the previously reported case of skull base PEComa involved an aggressive tumor with widespread metastasis. Here, we report the first case of a PEComa of the pterygopalatine fossa/retroantral region, which was treated conservatively. This rare pathology should be considered in the differential diagnosis for atypical skull base tumors.

Cutaneous "fibroma-like" perivascular epithelioid cell tumor: A case report and review of literature

Perivascular epithelioid cell tumors (PEComas) are a group of lesions sharing the common features of co-expression of melanocytic and myogenic markers, with focal association of the cells with vascular walls. The PEComa group exhibits a wide range of morphologies. A "fibroma-like" variant of PEComa has been recently described. The case reported herein is that of an infant with tuberous sclerosis complex (TSC) presenting with a lip mass. Excisional biopsy showed a moderately cellular tumor composed of spindled to stellate cells embedded within a collagenized stroma. The cells showed focal perivascular accumulation and positivity for both melanocytic (HMB-45) and myogenic (desmin) markers. This is the fifth reported case of "fibroma-like" PEComa in literature and the youngest patient to date. All of the "fibroma-like" PEComas were found in patients with tuberous sclerosis-hence, the diagnosis of this entity should prompt a workup for TSC; conversely, a fibroma-like lesion in a patient with TSC or with TSC-related conditions should be evaluated using melanocytic and myogenic markers. Melanocytic and myogenic markers are also useful in differentiating "fibroma-like" PEComa from other differential diagnoses such as fibroma and benign fibrous histiocytoma.

Malignant perivascular epithelioid cell tumor mimicking jugular foramen schwannoma: A case report and literature review

Background

Perivascular epithelioid cell tumors (PEComas) of the skull base are extremely rare. Here we report the first description of a malignant PEComa mimicking jugular foramen schwannoma and presenting as Collet-Sicard syndrome, and we review the previous literature on PEComas of the head, neck and skull base.

Case description

A 29-year-old woman presented with hoarseness, dysphagia, vomiting, and headache. She was first diagnosed with Collet-Sicard syndrome caused by thrombosis of the sigmoid and transverse sinuses. She was treated with anticoagulant therapy, and the hoarseness and paralysis of the accessory nerve improved. Later, at age 31, the hoarseness again worsened. At another hospital, enhanced computed tomography revealed a tumor in the jugular foramen extending to the neck and medially displacing the internal carotid artery. She was referred to our hospital for further examination and was diagnosed with jugular foramen schwannoma causing thrombosis of the sinuses. At the one-year follow-up, the tumor had grown rapidly and had started to surround the internal carotid artery. We therefore performed a tissue biopsy of the tumor in the jugular foramen and neck. Based on pathological analysis, we made a definitive diagnosis of malignant PEComa.

Conclusions

It may be extremely challenging to reach an accurate diagnosis of PEComa in the skull-base region, which can cause a delay in treatment initiation. When atypical clinical features for a skull-base tumor are found, we recommend preliminary biopsy to obtain a definitive diagnosis and initiate an appropriate treatment strategy as early as possible.

Perivascular epithelioid cell tumors (PEComa) in pregnancy with uterine rupture and ongoing abdominal gestation: A case report

Perivascular epithelioid cell tumors (PEComa) represent a rare family of tumors characterized by distinct histology and immunohistochemistry characteristics. Approximately one-quarter of reported cases are gynecologic in origin and associated pregnancies are rare. We report a case of PEComa in pregnancy with initial undiagnosed presentation at 18 weeks of gestation and subsequent presentation and diagnosis at 30 weeks of gestation. Abdominal pain led to the use of magnetic resonance imaging, which raised concerns about placentation abnormality and abdominal pregnancy. Exploratory laparotomy was notable for a 10 cm by 15 cm posterior uterine defect through which the placenta and amniotic sac containing the fetus were extruded. Placenta-like tissue was noted to be invading through the anterior wall of the uterus, which led to concern regarding placenta percreta. A total abdominal hysterectomy and bilateral salpingectomy were then performed, given the complete loss of normal uterine architecture. Pathology returned with findings of placenta accreta and PEComa. Indolent uterine rupture in the setting of PEComa led to an ongoing viable abdominal pregnancy. Uterine PEComa can masquerade as a placenta and lead to obstetrical complications.

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Perivascular epithelioid cell tumors (PEComa) can masquerade as a placenta.

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Perivascular epithelioid cell tumors can lead to uterine rupture during pregnancy.

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Uterine perivascular epithelioid cell tumors can be associated with tuberous sclerosis complex.

Huge renal epithelioid angiomyolipoma - A case report of a giant, benign renal mass

INTRODUCTION

Renal angiomyolipoma (also called renal hamartoma) is a benign Tumor, composed of adipose tissue, smooth muscle tissue, and blood vessels. Tumors more than 10 cm (referred to as "giant" AMLs) are infrequent and a very small number of reported cases were measured more than 20 cm. Epithelioid angiomyolipoma (EAML), is a rare variant of angiomyolipoma with malignant potential. There are less than 10 cases of huge EAML reported in English literature, that were all associated with recurrence and complications.

CASE PRESENTATION

Here we report a rare case of renal EAML in a 48-year-old male patient that was not associated with tuberous sclerosis. He was admitted to our hospital with a complaint of severe abdominal pain. Computer Tomography Scan (CT-scan), revealed two masses attached to the left kidney with a size of 32 × 22 × 8 cm and 20 × 10 × 3 cm. The patient underwent a radical left nephrectomy. Postoperative histopathological examination confirmed the diagnosis of an EAML. The two-year follow-up CT-scan showed no recurrence.

CONCLUSION

Malignant EAML, although rare, does exist. Thus, besides evaluations required for ruling out the diagnosis of renal sarcomas, surgeons must follow patients after total nephrectomy for possible recurrence. Benign cases can be completely cured by surgery and do not show recurrence at the end of the follow-up period.

Perivascular Epithelioid Cell Tumor of the Urinary Bladder: A Systematic Review

Perivascular epithelioid cell tumor (PEComa) of the urinary bladder is a rare neoplasm showing distinct melanocytic and smooth muscle differentiation. We aimed to review the clinicopathologic features of bladder PEComa using all the available cases in the literature, along with 2 new cases from our database. The patients included 15 females and 15 males with a mean age of 39.2 ± 15.3 years. Painless hematuria was the most common clinical presentation. The tumors were usually well circumscribed with a mean tumor size of 4.4 ± 2.7 cm. Bladder PEComas demonstrated nests, trabeculae, or sheets of epithelioid cells with intermixed spindled cells and numerous thin-walled vessels. Immunohistochemical studies showed that the tumors were positive for HMB45 (27/27), cathepsin (4/4), SMA (20/22), and caldesmon (3/3) and were negative for pan cytokeratin (0/18) and EMA (0/4). Molecular studies revealed that PEComa was associated with the TFE3 (n = 3) and EWSR1 (n = 1) gene rearrangements. Treatment included partial cystectomy (n = 18), transurethral resection (n = 8), and radical cystectomy (n = 4). Twenty patients had no evidence of disease during a mean follow-up time of 19.4 ± 17.2 months. Two patients had recurrence, and 1 patient died of metastatic disease. In conclusion, bladder PEComas demonstrate distinct morphologic and immunohistochemical features. Although most tumors follow a benign course, a small subset may develop metastasis and cause death.

Robotic wedge resection of a rare gastric perivascular epithelioid cell tumor: A case report

BACKGROUND

Perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal neoplasm that can arise in many different organs with a broad spectrum of biological behavior, from indolent to aggressive progression. Only ten cases of gastric PEComas have been reported in the English literature, which were treated with endoscopic, laparoscopic, or open resections. Due to its rarity, the optimal surgical management and prognosis of this tumor are still uncertain.

CASE SUMMARY

We present a case of robotic wedge resection of a 6.5 cm bleeding lesion of the gastric fundus located 3 cm below the esophago-gastric junction in a 55-year-old man. Biopsy revealed a malignant tumor with epithelioid cells focally positive for muscle markers desmin and smooth muscle actin. In addition, histology revealed that the tumor was positive for HMB-45, melan-A (MART-1), microphthalmia transcription factor and negative for pan-cytokeratin AE1/AE3, CD34, p40, DOG-1, CD117 (c-kit), S100, CD3, CD79a, caldesmon and myogenin. These markers suggested the possibility of a PEComa. The patient underwent a diagnostic laparoscopy via the da Vinci® Si™ system and robotic wedge resection. Final pathology confirmed a malignant gastric PEComa with negative margins. At his 11-mo follow-up visit, the patient remained disease-free.

CONCLUSION

Gastric PEComa can be treated with a robotic R0 resection with acceptable postoperative and short-term oncological outcomes.

Uterine Mesenchymal Tumors: Update on Classification, Staging, and Molecular Features

The spectrum of mesenchymal neoplasia in the uterus has expanded in recent years. First, the identification of prevalent, recurrent molecular alterations has led to a more biologically and clinically congruent classification of endometrial stromal tumors. Likewise, the diagnostic criteria of several rare and miscellaneous tumor types have been refined in recent case series (Perivascular Epithelioid Cell tumor, inflammatory myofibroblastic tumor). Pure mesenchymal tumors are still broadly classified based on morphology according to the tumor cell phenotype. Smooth muscle tumors predominate in frequency, followed by tumors of endometrial stromal derivation; the latter are covered in depth in this article with an emphasis on defining molecular alterations and their morphologic and clinical correlates. The remaining entities comprise a miscellaneous group in which cell derivation does not have a normal counterpart in the uterus (eg, rhabdomyosarcoma) or is obscure (eg, undifferentiated uterine sarcoma). This article discusses their clinical relevance, recent insights into their molecular biology, and the most important differential diagnoses. Regarding the latter, immunohistochemistry and (increasingly) molecular diagnostics play a role in the diagnostic workup. We conclude with a few considerations on intraoperative consultation and macroscopic examination, as well as pathologic staging and grading of uterine sarcomas as per the most recent American Joint Cancer Commission and the Fédération Internationale de Gynécologie et d'Obstétrique staging systems.

Malignant Perivascular Epitheloid Cell Tumor with an Unusual Immunophenotype in a Ten-Year-Old Child

Introduction: Perivascular epitheloid cell tumors (PEComa) represent a group of usually benign mesenchymal neoplasms. Malignant variants are usually found only in adults.Case: We present a 10-year-old girl with infraclavicular malignant PEComa, negative for HMB-45 and Melan A but focally positive for MITF.Conclusion: To the best of our knowledge, no malignant variant of PEComa has been described in soft tissue in a child. Generally, PEComas are immunoreactive for HMB-45 and/or Melan A while our case was negative for both. Further studies are necessary to elucidate the significance of this immunohistochemical finding.

Retroperitoneal perivascular epithelioid cell tumours: A case report and review of literature

BACKGROUND

The perivascular epithelioid cell tumour (PEComa) family of tumours mainly includes renal and hepatic angiomyolipomas, pulmonary lymphangioleiomyomatosis and clear cell “sugar” tumour of the lung. Several uncommon tumours with similar morphological and immunophenotypical characteristics arising at a variety of sites (abdominal cavity, digestive tract, retroperitoneum, skin, soft tissue and bones) are also included in the PEComa family and are referred to as PEComas not otherwise specified.

CASE SUMMARY

We present a 37-year-old female patient who underwent resection of an 8.5 cm × 8 cm × 4 cm retroperitoneal tumour, which eventually was diagnosed as PEComa of uncertain biological behaviour. Three years after the operation, the patient remains without any evidence of recurrence. A search was performed in the Medline and EMBASE databases for articles published between 1996 and 2018, and we identified 31 articles related to retroperitoneal and perinephric PEComas. We focused on sex, age, maximum dimension, histological and immunohistochemical characteristics of the tumour, follow-up and long-term outcome. Thirty-four retroperitoneal (including the present one) and ten perinephric PEComas were identified, carrying a malignant potential rate of 44% and 60%, respectively. Nearly half of the potentially malignant PEComas presented with or developed metastases during the course of the disease.

CONCLUSION

Retroperitoneal PEComas are not as indolent as they are supposed to be. Radical surgical resection constitutes the treatment of choice for localized disease, while mammalian target of the rapamycin (mTOR) inhibitors constitute the most promising therapy for disseminated disease. The role of mTOR inhibitors as adjuvant or neoadjuvant therapies needs to be evaluated in the future.

Granular cell tumors overexpress TFE3 without gene rearrangement: Evaluation of immunohistochemistry and break-apart FISH in 45 cases

Transcription factor E3 (TFE3) is a useful marker for tumors with Xp11.2 translocation, including alveolar soft part sarcoma and renal cell carcinoma. Recently, TFE3 overexpression was also found in granular cell tumors (GrCTs). However, the case cohorts of these two studies were limited to only 11 and 6 cases. Whether aberrant TFE3 expression is a common feature of Asian patients with GrCT requires further investigation. In the present study, immunohistochemical staining and TFE3 break-apart fluorescence in situ hybridization (FISH) assay were performed in 45 samples of GrCTs obtained from Chinese patients recruited from three medical centers in northeast China. Diffusive and marked nuclear staining for TFE3 was identified in 11/45 (24%) cases, which was lower than previously reported. Focal or weak TFE3 staining was identified in 13/45 (29%) cases. The remaining 21 cases were negative stained. In addition, GrCTs in subcutaneous tissue exhibited a relatively higher ratio (8/45, 18%) for TFE3 expression, compared with those in other sites. Furthermore, according to FISH data, no rearrangement or amplification of TFE3 was identified in these cases, whether they were positively or negatively stained for TFE3. The results from the present study demonstrated that part of patients GrCTs exhibited TFE3 overexpression, which suggested that this may not be derived from gene rearrangement.

Uterine PEComas: A Morphologic, Immunohistochemical, and Molecular Analysis of 32 Tumors

Uterine perivascular epithelioid cell tumors (PEComas) are rare neoplasms that may show overlapping morphology and immunohistochemistry with uterine smooth muscle tumors. In this study, we evaluated the morphologic, immunohistochemical, and molecular features of 32 PEComas, including 11 with aggressive behavior. Two distinct morphologies were observed: classic (n=30) and those with a lymphangioleiomyomatosis appearance (n=2). In the former, patients ranged from 32 to 77 (mean: 51) years and 13% had tuberous sclerosis. Tumors ranged from 0.2 to 17 (mean: 5.5) cm with 77% arising in the corpus. Epithelioid cells were present in 100% and a spindled component was seen in 37%. Nuclear atypia was low (53%), intermediate (17%), or high (30%). Mitoses ranged from 0 to 36 (mean: 6) and 0 to 133 (mean: 19) per 10 and 50 high-power fields, with atypical mitoses present in 30%. Thin and delicate vessels were noted in 100%, clear/eosinophilic and granular cytoplasm in 93%, stromal hyalinization in 73%, necrosis in 30%, and lymphovascular invasion in 10%. All tumors were positive for HMB-45, cathepsin K, and at least one muscle marker, with most expressing melan-A (77%) and/or MiTF (79%). A PSF-TFE3 fusion was identified in one while another showed a RAD51B-OPHN1 fusion. Follow-up ranged from 2 to 175 (mean: 41) months, with 63% of patients alive and well, 20% dead of disease, 13% alive with disease, and 3% dead from other causes. In the latter group (n=2), patients were 39 and 49 years old, one had tuberous sclerosis, while the other had pulmonary lymphangioleiomyomatosis. Both tumors expressed HMB-45, cathepsin K, and muscle markers, but lacked TFE3 and RAD51B rearrangements. The 2 patients are currently alive and well. Application of gynecologic-specific criteria (≥4 features required for malignancy: size ≥5 cm, high-grade atypia, mitoses >1/50 high-power fields, necrosis, and lymphovascular invasion) for predicting outcome misclassified 36% (4/11) of aggressive tumors; thus, a modified algorithm with a threshold of 3 of these features is recommended to classify a PEComa as malignant.

Perivascular Epithelial Cell Tumor of the Pancreas Diagnosed Preoperatively by Endoscopic Ultrasound-guided Fine-needle Aspiration

We herein report a 49-year-old woman with a perivascular epithelial cell tumor (PEComa) of the pancreas. Imaging studies demonstrated a relatively well-demarcated mass, measuring approximately 40 mm in diameter, located in the pancreatic tail. It was heterogeneously enhanced almost to the same degree as the surrounding pancreatic tissue in both the arterial and portal venous phases. We performed endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) using the Acquire^® 22-gauge needle and preoperatively obtained a definitive diagnosis with a sufficient sample. Clinicians should consider pancreatic PEComa in their differential diagnosis of patients with a pancreatic mass.

Perivascular epitheliod cell tumors: Study of three gynecological cases

ANTECEDENTS

Perivascular epitheliod cell tumor (PEComa) is a rare mesenchymal tumor. They are rare in the field of gynecology, which makes them difficult to consider as a possible diagnostic. We aim to contribute with our experience to ease clinical practice to others gynecologists.

PATIENTS AND METHODS

We contribute to literature with three gynecological cases; uterine, vaginal and retroperitoneal PEComas.

RESULTS

The uterine and vaginal PEComa, have required surgical treatment, and are free of disease at 9 and 5 months respectively. The retroperitoneal PEComa has recurred at 72 months of follow-up in form of retroperitoneal mass and pulmonary lymphangioleomyomatosis, continues treatment with sirolimus with good tolerance and partial response.

DISCUSSION

Given the scarcity of cases, the literature consists of case reports and mini-reviews. Some authors have categorized the PEComas based on prognostic factors, but there is no agreement regarding the follow-up and treatment. ¹⁸F-FDG-PET/CT can help characterize these lesions. The surgery is the standard. In recurrent or malignant cases, there is a lack of evidence regarding chemotherapy and radiotherapy. New therapies with inhibitory m-TOR open a hopeful therapeutic window.

Malignant Perivascular Epithelioid Cell Tumor of Lung on FDG PET/CT

Chest CT images were acquired in a 67-year-old man to evaluate a left lung mass revealed by chest radiography. The image findings suggested possible pulmonary malignancy. FDG PET/CT was performed for staging, which showed the abnormally increased activity in the lung mass with hypermetabolic lymph node. Pathology from the biopsy confirmed malignant perivascular epithelioid cell tumor.

Gastric Perivascular Epithelioid Cell Tumor (PEComa)

OBJECTIVES

To review the clinicopathologic, immunophenotypic, and molecular features of gastric perivascular epithelioid cell tumor (PEComa).

METHODS

We identified two new cases of gastric PEComa and summarized the clinical and pathologic characteristics of this rare neoplasm.

RESULTS

The first case was a 48-year-old woman who was treated with an endoscopic submucosal dissection (ESD), and the second case was a 64-year-old man who received a distal gastrectomy. Microscopic examination showed one tumor was composed of purely epithelioid cells, while the other was composed of epithelioid and spindle cells. Both tumors were immunoreactive for melanocytic markers (HMB45 and Melan-A), smooth muscle actin, and vimentin. No TFE3 gene rearrangement was identified by fluorescence in situ hybridization in either case.

CONCLUSIONS

Gastric PEComa is an exceedingly rare neoplasm, with only seven other reported cases to date. We are the first to report the results of molecular assays for the TFE3 gene rearrangement associated with gastric PEComa.

Role of Chemotherapy, VEGFR Inhibitors, and mTOR Inhibitors in Advanced Perivascular Epithelioid Cell Tumors (PEComas)

PURPOSE

Perivascular epitheliod cell tumors (PEComas) are rare mesenchymal neoplasms for which the role of systemic treatments is not established as there are no published prospective clinical trials or sufficiently large retrospective case series. The aim of this study is to clarify the activity of conventional chemotherapy and biological agents in advanced/metastatic PEComas.

EXPERIMENTAL DESIGN

This was an observational, retrospective, international study that included patients with advanced/metastatic PEComa treated with systemic therapy at 5 European sarcoma reference centers and within the Italian Rare Cancer Network. Survival analyses were performed using the Kaplan-Meier method and the Cox hazards regression models.

RESULTS

A total of 53 patients were included. Cytotoxic chemotherapy regimens were active only in a small proportion of PEComas. Gemcitabine-based regimens [objective response rate (ORR): 20%, median progression-free survival (PFS): 3.4 months] seemed to have the same activity of anthracycline-based regimens (ORR: 13%, median PFS: 3.2 months). Antiangiogenic agents resulted in disease stabilization in some patients, with a number having density changes/tissue response on imaging, with an ORR of 8.3% and a median PFS of 5.4 months. mTOR inhibitors were the most active agents, with an ORR of 41% and a median PFS of 9 months.

CONCLUSIONS

Our study provides data for the selection of systemic therapy in patients with advanced/metastatic PEComa: mTOR inhibitors are the most active agents. Antiangiogenics and chemotherapy with gemcitabine-based regimens or anthracycline-based regimens are options in further line, but with a lower response rate and PFS.

[Complexity of PEComas : Diagnostic approach, molecular background, clinical management (German version)]

Perivascular epithelioid cell neoplasms (PEComas) are a family of mesenchymal neoplasms with features of both melanotic and smooth muscle differentiation. PEComa morphology is highly variable and encompasses epithelioid to spindle cells often with clear cytoplasm and prominent nucleoli. Molecularly, most PEComas are defined by a loss of function of the TSC1/TSC2 complex. Additionally, a distinct small subset of PEComas harboring rearrangements of the TFE3 (Xp11) gene locus has been identified. By presenting a series of three case reports with distinct features, we demonstrate diagnostic pitfalls as well as the importance of molecular work-up of PEComas because of important therapeutic consequences.

Intra-articular fibroma-like perivascular epithelioid tumor (PEComa) mimicking tenosynovial giant cell tumor, diffuse type

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms composed of perivascular epithelioid cells that are immunoreactive for both melanocytic and myogenic markers. Recently, a fibroma-like PEComa associated with tuberous sclerosis complex (TSC) has been identified. We describe the first intra-articular case of a fibroma-like PEComa in a 44-year-old man who presented with a hypointense intra-articular knee mass, which was mistaken for tenosynovial giant cell tumor, diffuse type. This case report demonstrates that fibroma-like PEComa should be included in the extended differential diagnosis of intra-articular soft tissue masses. In addition, given their strong association with TSC mutations, a diagnosis of fibroma-like PEComa should trigger an evaluation for TSC.

First pancreatic perivascular epithelioid cell tumor (PEComa) treated by mTOR inhibitor

BACKGROUND

Perivascular epithelioid cell tumor, an extremely rare mesenchymal tumor, could be ubiquitous but rarely arises from pancreas. Surgery is considered the most appropriate treatment. Nevertheless, activation of mTOR pathway seems to be a common pathogenic event in PEComas paving the way to chemotherapy by mTOR inhibitor.

METHOD

A 17 year-old man presented a hypervascular tumor of 55 mm, located in the head of pancreas without bile duct or pancreatic duct compression.

RESULTS

Histopathology showed epithelioid cells with clear or focally granular eosinophilic cytoplasm with melanocytic (HMB-45, Melan-A) and myoid markers which confirmed diagnosis of PEComa. Given the absence of worrisome feature, we ruled out surgery and decided to initiate treatment with Sirolimus, an mTOR inhibitor. After 3.5 years, we showed a significant reduction in size of the tumor.

CONCLUSION

This first case of pancreatic PEComa treated by mTOR inhibitor without surgery suggests a good efficiency of this therapy.

Practical Application of Cytology and Core Biopsy in the Diagnosis of Mesenchymal Tumors

Soft tissue neoplasms are increasingly being sampled by core needle biopsy and fine-needle aspiration (FNA), and these small biopsy specimens pose unique diagnostic challenges. Many advances in ancillary testing enable detection of characteristic immunophenotypes and molecular alterations, allowing accurate classification of soft tissue tumors in these small biopsy samples. This review outlines pattern-based diagnostic approaches to core biopsies and FNAs of soft tissue neoplasms, including formulation of practical differential diagnoses and relevant application of ancillary tests.

TFE3-expressing primary perivascular epithelioid cell tumor of the Lymph node mimicking nodal relapse of rectal cancer: A case report

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TFE3-expressing PEComa has unique morphological and immunohistochemical features.

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PEComa can mimic lymph node relapse of rectal cancer.

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Surgical excision can aid a proper diagnosis of suspicious lesions in rectal cancer.

Introduction

Perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal neoplasm.

Presentation of case

We treated a 50-year-old woman who underwent neoadjuvant chemoradiotherapy followed by low anterior resection and adjuvant chemotherapy for ystage IIIB rectal adenocarcinoma. The patient was diagnosed with metastatic rectal adenocarcinoma in the right lower lobe of the lung after 14 months of follow-up. Later, after 3 years of follow-up, a mass in the gastrosplenic area was revealed by computed tomography, which was considered indicative of metachronous mass relapse. The patient underwent partial omentectomy, and an enlarged mass measuring 2.2 × 1.3 cm was found. Microscopic findings revealed an alveolar-like collection of epithelioid cells surrounded by a thin-wall vascular channel within a lymph node (LN). These epithelioid cells were positive for HMB45 and TFE3 but negative for Melan-A, CK, and S100. The patient was finally diagnosed with TFE3-expressing primary PEComa of LN.

Discussion

We report a rare case of TFE3-expressing primary LN PEComa that mimicked nodal recurrence of rectal cancer. Thus, imaging results in patients affected by neoplasm present a clinical diagnostic dilemma, as the presence of newly onset PEComa of LN may lead to the erroneous diagnosis of tumor recurrence or progression.

Conclusion

Suspicious isolated recurrences of rectal cancer in unusual locations may require surgical excision to confirm definitive diagnosis.

Ischiorectal fossa: benign and malignant neoplasms of this "ignored" radiological anatomical space

PURPOSE

To review the pertinent anatomy and the imaging features of common and uncommon benign and malignant neoplasms and masses of the ischiorectal fossa.

RESULTS

The ischiorectal or ischioanal fossa is the largest space in the anorectal region. The benign neoplasms that develop in the ischiorectal originate from the different components that forms the fossa including vascular tumors such as aggressive angiomyxoma or hemangioma; neural tumors as plexiform neurofibroma or schwannoma; fat tumors as lipoma; skin/skin appendages tumors as hidradenoma papilliferum; smooth or skeletal muscle tumors as solitary fibrous tumor. The malignant neoplasms that develop in the ischiorectal fossa also originate from different components that forms the fossa including vascular tumors such as angiosarcoma, neural tumors as malignant granular cell tumor and malignant peripheral nerve sheath tumor; fat tumors as liposarcoma; smooth or skeletal muscle tumors as leiomyosarcoma, rhabdomyosarcoma, malignant PEComa, or undifferentiated pleomorphic sarcoma. Additionally, the ischiorectal fossa can also harbor secondary hematogenous metastases and be affected by direct invasion from neoplasms of adjacent pelvic organs and structures. Furthermore, other miscellaneous masses can occur in the ischiorectal fossa including congenital and developmental lesions, and inflammatory and infectious processes.

CONCLUSION

Knowledge of the anatomy, and the spectrum of imaging findings of common and uncommon benign and malignant neoplasms of the ischiorectal fossa is crucial for the radiologists during interpretation of images allowing them to make contributions to the diagnosis and better patient management.

[A suspected carcinoma finding in the uterus]

Epithelioid tumor cells of a uterine perivascular epithelioid cell tumor (PEComa) may mimic carcinoma cells in an endometrial sampling (pitfall). Immunohistochemistry (HMB45 positive, keratin negative) helps in the differential diagnosis.

PEComa of the talus: a unique case of a soft tissue tumor within bone

INTRODUCTION

Perivascular epithelioid cell tumor (PEComa) is a family of rare mesenchymal tumors composed of histologically and immunohistochemically distinctive perivascular epithelioid cells (PECs). These tumors have been described at multiple anatomic sites. PEComas presenting in bone are especially rare and they have been reported to be either primary or metastatic lesions. None of them is located at the level of the foot.

PATIENT

We report on a case of primary bone PEComa of the talus, the first one to be published to the best of our knowledge. Treatment and result: Limb sparing surgical treatment has been done using intralesional tumor removal, burring and application of argon beam at the tumor walls and primary filling of the tumor cavity by bone cement with so far absence of any tumor recurrence documented by multiple histological sections at second look operation nine months after primary surgery, where cement has been replaced by autologous bone graft, and by subsequent follow-up.

CONCLUSIONS

PEComa is a very rare tumor, and its presence in bone is especially rare. The here reported case of PEComa presenting at the level of the talus is, to the best of our knowledge, the first case to be reported in the literature.

Malignant hepatic vascular tumors in adults: Characteristics, diagnostic difficulties and current management

Malignant vascular tumors of the liver include rare primary hepatic mesenchymal tumors developed in the background of a normal liver parenchyma. Most of them are detected incidentally by the increased use of performing imaging techniques. Their diagnosis is challenging, involving clinical and imaging criteria, with final confirmation by histology and immunohistochemistry. Surgery represents the mainstay of treatment. Liver transplantation (LT) has improved substantially the prognosis of hepatic epithelioid hemangioendothelioma (HEHE), with 5-year patient survival rates of up to 81%, based on the European Liver Intestine Transplantation Association-European Liver Transplant Registry study. Unfortunately, the results of surgery and LT are dismal in cases of hepatic angiosarcoma (HAS). Due to the disappointing results of very short survival periods of approximately 6-7 mo after LT, because of tumor recurrence and rapid progression of the disease, HAS is considered an absolute contraindication to LT. Recurrences after surgical resection are high in cases of HEHE and invariably present in cases of HAS. The discovery of reliable prognostic markers and the elaboration of prognostic scores following LT are needed to provide the best therapeutic choice for each patient. Studies on a few patients have demonstrated the stabilization of the disease in a proportion of patients with hepatic vascular tumors using novel targeted antiangiogenic agents, cytokines or immunotherapy. These new approaches, alone or in combination with other therapeutic modalities, such as surgery and classical chemotherapy, need further investigation to assess their role in prolonging patient survival. Personalized therapeutic algorithms according to the histopathological features, behavior, molecular biology and genetics of the tumors should be elaborated in the near future for the management of patients diagnosed with primary malignant vascular tumors of the liver.

Tibial perivascular epithelioid cell tumour (PEComa). A case report and literature review

INTRODUCTION

Perivascular epithelioid cell (PEC) is a cell type constantly present in a group of tumours including angiomyolipoma (AML), clear-cell «sugar» tumour (CCST) of the lung and extrapulmonary sites, lymphangioleiomyomatosis (LAM), and clear-cell tumours of other anatomical sites. It has morphologic distinctive features: epithelioid appearance with a clear to granular cytoplasm, a round to oval, centrally located nucleus and an inconspicuous nucleolus. Immunohistochemically, PEC expresses myogenic and melanocytic markers. Eleven cases of primary bone PEComa presentation have been described since 2002.

OBJECTIVE

To report a case of primary bone perivascular epithelioid cell tumour.

CASE REPORT

24 year-old male presented with pain. X-ray revealed an osteolytic lesion at right proximal tibia with soft tissue extension. Evaluation of slides identified a bony perivascular epithelioid cell tumour without immunohistochemical study confirmation.

RESULTS

Patient was treated by surgical excision and adjuvant chemotherapy (epirubicin/cysplatin). After two years of follow-up the patient remains disease free.

CONCLUSIONS

This is the first-case report in Latin America. Immunohistochemical stains were negative and we believe it may be due to non-described ethnic variations.

Malignant perivascular epithelioid cell tumor of the lung synchronous with a primary adenocarcinoma: one case report and review of the literature

BACKGROUND

Perivascular Epithelioid Cell Tumors (PEComa) is an extraordinarily rare mesenchymal neoplasm especially the malignant type originating from the lung. To date, only 8 cases of malignant or malignant potential pulmonary PEComa had been documented. Firm diagnostic criteria for malignant pulmonary PEComa need urgently to be established.

CASE PRESENTATION

We report a challenging case of malignant pulmonary PEComa combined with a primary adenocarcinoma in a 54-year-old man. The PEComa-like tumor showed strong Melan-A and weak transcription factor E3 (TFE3) protein expression but no TFE3 gene rearrangement. The carcinoma-like nodule was recognized as a poorly differentiated primary lung adenocarcinoma.

DISCUSSION AND CONCLUSIONS

Our case report was the first case of malignant pulmonary PEComa synchronous with a primary adenocarcinoma and studied the dilemma of diagnosing benign versus malignant criteria for this uncommon tumor.

Histiocyte-rich rhabdomyoblastic tumor: rhabdomyosarcoma, rhabdomyoma, or rhabdomyoblastic tumor of uncertain malignant potential? A histologically distinctive rhabdomyoblastic tumor in search of a place in the classification of skeletal muscle neoplasms

Skeletal muscle tumors are traditionally classified as rhabdomyoma or rhabdomyosarcoma. We have identified an unusual adult rhabdomyoblastic tumor not clearly corresponding to a previously described variant of rhabdomyoma or rhabdomyosarcoma, characterized by a very striking proliferation of non-neoplastic histiocytes, obscuring the underlying tumor. Ten cases were identified in nine males and one female with a median age of 43 years (range 23-69 years). Tumors involved the deep soft tissues of the trunk (N = 4), lower limbs (N = 4), and neck (N = 2). Tumors were well-circumscribed, nodular masses, frequently surrounded by a fibrous capsule containing lymphoid aggregates and sometimes calcifications. Numerous foamy macrophages, multinucleated Touton-type giant cells, and sheets/fascicles of smaller, often spindled macrophages largely obscured the underlying desmin, MyoD1, and myogenin-positive rhabdomyoblastic tumor. Cases were wild type for MYOD1 and no other mutations or rearrangements characteristic of a known subtype of rhabdomyoma or rhabdomyosarcoma were identified. Two of four cases successfully analyzed using a next-generation sequencing panel of 170 common cancer-related genes harbored inactivating NF1 mutations. Next-generation sequencing showed no gene fusions. Clinical follow (nine patients; median 9 months; mean 23 months; range 3-124 months) showed all patients received wide excision; four patients also received adjuvant radiotherapy and none received chemotherapy. At the time of last follow-up, all patients were alive and without disease; no local recurrences or distant metastases occurred. We hypothesize that these unusual tumors represent rhabdomyoblastic tumors of uncertain malignant potential. Possibly over time they should be relegated to a new category of skeletal muscle tumors of intermediate (borderline) malignancy.

Extrapulmonary uterine lymphangioleiomyomatosis (LAM) and dysfunctional uterine bleeding: the first presentation of LAM in a tuberous sclerosis complex patient

Lymphangioleiomyomatosis (LAM) is a rare disease that typically affects women of childbearing age. It most commonly affects the lungs (P-LAM) but can occasionally occur in extra-pulmonary sites (E-LAM). There is a strong association between LAM and the tuberous sclerosis complex (TSC). We report a case of a 42-year-old female TSC sufferer who presented with dysfunctional uterine bleeding. She was not known to have LAM. An endometrial biopsy revealed a spindled-cell lesion suspicious of leiomyosarcoma, which correlated with cross-sectional imaging. She underwent a hysterectomy that showed a bizarre (symplastic) leiomyomatous endometrial polyp with background uterine LAM. We discuss the clinical and pathological implications of this unusual case of E-LAM and the importance of clinicopathological correlation in TSC sufferers. The association of uterine LAM with TSC is important and LAM should be considered as a differential of dysfunctional uterine bleeding and a benign mimic to uterine leiomyosarcoma in patients with TSC.

Hepatic angiomyolipoma with early drainage veins into the hepatic and portal vein

Hepatic angiomyolipoma (AML) is a rare stromal tumor composed of variable admixtures of thick-walled vessels, smooth muscles and adipose tissue. One of the specific radiological findings of hepatic AML is an early drainage vein noted via enhanced computed tomography (CT). We report a case of hepatic AML showing early drainage veins into both the hepatic and portal vein. The case involved a 46-year-old woman who was referred to our hospital because of a giant hepatic tumor. CT revealed well-enhanced 14 cm and 1 cm tumors in the left and right lobes, respectively. Magnetic resonance imaging demonstrated the existence of adipose tissues in the larger tumor. Hepatic arteriography revealed early drainage veins draining into both the hepatic and portal vein. Based on a diagnosis of hepatic AML, left hepatectomy and partial hepatectomy were performed. Pathology revealed both tumors as hepatic AML based on human melanoma black-45 immuno-positivity. Hepatic AML with early drainage veins into both the hepatic and portal vein is rare. The dilated and retrogressive vein drains the abundant arterial blood flow of the tumor. The finding of early drainage veins into not only the hepatic vein but also the portal vein should be helpful for diagnosing hepatic AMLs.