Abdominopelvic sarcoma of perivascular epithelioid cells. Report of four cases in young women, one with tuberous sclerosis

Soft Tissue Perivascular Epithelioid Cell Tumors

Perivascular epithelioid cell tumors (PEComas) are a heterogenous group of mesenchymal neoplasms with a mixed myomelanocytic immunophenotype. PEComa-family tumors include angiomyolipoma, lymphangioleiomyomatosis, and a large category of rare neoplasms throughout the body that are now classified under the umbrella term "PEComa." This review focuses on recent advances in the clinicopathological and molecular features of PEComas, with an emphasis on PEComas that originate in soft tissue.

Perivascular epithelioid cell tumors (PEComas) of the bone and soft tissue: a Japanese Musculoskeletal Oncology Group (JMOG) multi-institutional study

PURPOSE

Perivascular epithelioid cell tumors (PEComas) of the bone and soft tissues are rare mesenchymal neoplasms, some of which are malignant. However, their clinical and pathological characteristics remain unclear. This study was performed to investigate the clinical and pathological characteristics of PEComas in bone and soft tissues by leveraging information from the Japanese Musculoskeletal Oncology Group.

METHODS

Nine patients, including four male and five female patients with a median age of 50 years, were retrospectively reviewed. PEComas of the visceral organs, including the uterus and retroperitoneum, were excluded.

RESULTS

Eight tumors arose in the soft tissue and one in the bone, with a mean size of 8.8 cm. Four patients showed local recurrence or distant metastasis. The 1-year survival rate was 78%. Pathologically, eight tumors were classified as malignant and one as having uncertain malignancy potential. Half of the tumors showed high MIB-1 index values of > 30%. Immunohistochemically, the melanocyte marker HMB45 was expressed in 89% of the cases, and muscle-specific markers were expressed only in 30-50% of the cases. Transcription factor binding to IGHM enhancer 3 (TFE3) expression was positive in 100% of the patients. Tumors with high expression of TFE3 were classified as PEComas with malignant potential according to Folpe's classification.

CONCLUSIONS

Bone and soft tissue PEComas may have a higher malignancy potential than other visceral PEComas and are more likely to develop as TFE3-rearranged PEComas.

Cervical PEComa: Challenges in diagnosis and prognosis of a rare neoplasm

•Cervical PEComas are rare neoplasms which present a diagnostic challenge.•Large tumour size is an important clinical prognosticator in cervical PEComa.•All reported cases of cervical PEComa classified as benign by Folpe criteria behaved in benign fashion clinically.•Tumours ≤ 4 cm may be assessed with cone biopsy, and simple hysterectomy considered if no adverse pathologic features.•Molecular characterization and linkage with coordinated rare tumour registries may identify novel treatments.

Soft Tissue Sarcoma Mimicking Melanoma: A Systematic Review

BACKGROUND

Sarcoma may show similarities to malignant melanoma in terms of morphologic and immunohistochemical aspects, making it difficult to differentiate between these two neoplasms during the diagnostic process. This systematic review aims to summarize available evidence on cases of sarcoma that were initially diagnosed as melanoma.

METHODS

A comprehensive search of the MEDLINE/Pubmed, EMBASE, and SCOPUS databases was conducted through March 2023. We included case series and case reports of sarcoma patients that were initially diagnosed as malignant melanoma. PRISMA guidelines were followed.

RESULTS

Twenty-three case reports and four case series with a total of 34 patients were included. The clinical presentation was heterogeneous, and the most involved anatomical regions were lower limbs (24%), head/neck (24%), and upper limbs (21%). IHC positivity was reported for S100 (69%), HMB45 (63%), MelanA (31%), and MiTF (3%). The main reasons for a second assessment were unusual presentation (48%) and uncertain diagnosis (28%). EWSR1 translocation was investigated in 17/34 patients (50%) and found to be positive in 16/17 (94%). The final diagnosis was clear cell sarcoma (50%) or other soft tissue sarcomas (50%).

CONCLUSIONS

Melanoma and some histotypes of sarcoma share many similarities. In cases of atypical lesions, a second diagnosis should be considered, and ESWR1 translocation should be investigated.

Malignant perivascular epithelioid cell tumor (PEComa) of the uterus

BACKGROUND

Perivascular epithelioid cell tumors (PEComas) of the uterus is a rare type of mesenchymal tumors associated with myelomelanocytic differentiation and distinctive histological appearances. So far, the reported cases of uterine PEComas are usually benign. Documented malignant cases with aggressive behavior appear to be less common.

CASE PRESENTATION

We report a 37-year-old female who received abdominal hysterectomy for uterine tumor in a local hospital. She was diagnosed with uterine leiomyosarcoma and referred to Hubei Cancer Hospital. Her histological slides were reviewed and immunohistochemical staining for specific markers of epithelial, melanocytic, myoid and some others were analyzed. The pathologic diagnosis was malignant uterine PEComa. Systematic imaging of the patient further revealed an abdominal para-aortic mass. She received pelvic and para-aortic lymph node dissection. Postoperative histology revealed para-aortic lymph nodal metastasis of malignant uterine PEComa. She received 8 cycles of chemotherapy after surgery. The chemotherapy regiment was epirubicin plus ifosfamide The patient is free of recurrence and metastasis 6 years after surgical resection.

CONCLUSION

Uterine PEComas are indistinguishable from other uterine tumors such as leiomyoma and leiomyosarcoma before pathologic diagnosis could be made. For patients with malignant uterine PEComas, removal of both primary lesions and metastatic foci, if any, needs to be attempted. Postoperative chemotherapy or radiotherapy should also be considered in patients with distant metastases or positive lymph nodes.

Natural History and Treatment Strategies of Advanced PEComas: A Systematic Review

Simple Summary

In this article, we review the clinical features of advanced PEComas and show the diversity of reported data among authors, emphasizing the heterogeneity of molecular characterization and treatment strategy. Based on clinical data collected from 124 case reports, metastatic disease at diagnosis and a grouped version of the Bleeker’s risk category were the only factors significantly associated with death. Due to a significant number of missing data or short follow-ups, results regarding prognostic factors should, however, be interpreted with caution.

Abstract

PEComas is a family of rare mesenchymal tumors. This systematic review aims to better understand the natural history of advanced PEComas. After a search on the PubMed database and main oncology meeting libraries according to the PRISMA guidelines, 88 articles reported in the English literature were included. Data on clinical and histological features, treatments and outcomes were collected. To identify risk factors, univariate and multivariate analyses were performed. Seven cohorts of patients and 124 individual patients were identified. Focusing on case reports, most patients were metastatic, and the median overall survival (OS) of the entire cohort was 60 months (95%CI 33; NA). Risk factors significantly associated with OS in the multivariate analysis were the presence of metastasis at diagnosis (HR: 2.59, 95%CI 1.06; 6.33, p = 0.036) and the grouped-Bleeker’s risk category (HR: 4.66; 95%CI 1.07; 20.19; p = 0.039). In the metastatic population, only the presence of lymph node metastasis was associated with OS (HR: 3.11; 95%CI 1.13; 8.60, p < 0.05). Due to a lack of events, it was not possible to conclude on other factors. This review of the literature highlights the heterogeneity of literature data and shows the great diversity of clinical management strategies.

Tuberous Sclerosis: Current Update

Tuberous sclerosis complex (TSC) is a relatively rare autosomal dominant neurocutaneous disorder secondary to mutations in the TSC1 or TSC2 tumor suppressor genes. Although manifestation of the classic triad of seizures, intellectual disability, and facial angiofibromas may facilitate timely diagnosis of TSC, the multisystem features that may indicate TSC in the absence of these manifestations remain highly variable. In addition, patients with TSC are at risk of developing multiple benign and malignant tumors in various organ systems, resulting in increased morbidity and mortality. Thus, imaging plays a critical role in diagnosis, surveillance, and management of patients with TSC. It is crucial that radiologists be familiar with TSC and the various associated imaging features to avoid a delayed or incorrect diagnosis. Key manifestations include cortical dysplasias, subependymal nodules, subependymal giant cell astrocytomas, cardiac rhabdomyomas, lymphangioleiomyomatosis, and angiomyolipomas. Renal angiomyolipomas in particular can manifest with imaging features that mimic renal malignancy and pose a diagnostic dilemma. Other manifestations include dermatologic and ophthalmic manifestations, renal cysts, renal cell carcinomas, multifocal micronodular pneumocyte hyperplasia, splenic hamartomas, and other rare tumors such as perivascular epithelioid tumors. In addition to using imaging and clinical features to confirm the diagnosis, genetic testing can be performed. In this article, the molecular pathogenesis, clinical manifestations, and imaging features of TSC are reviewed. Current recommendations for management and surveillance of TSC are discussed as well. ^©RSNA, 2021.

Gynaecological perivascular epithelioid cell tumour (PEComa): comparative analysis of proposed algorithms for prediction of clinical outcome

AIMS

Perivascular epithelioid cell tumours (PEComas) are rare mesenchymal tumours that coexpress smooth muscle and melanocytic markers. They have a predilection for gynaecological organs, where they present a unique diagnostic challenge, because of morphological and immunohistochemical overlap with more common smooth muscle and stromal tumours. Limited information regarding the natural history, owing to the rarity of this tumour, makes accurate risk stratification difficult. We aimed to review clinicopathological features of gynaecological PEComa and compare accuracy of five different classification systems for prediction of prognosis.

METHODS AND RESULTS

We have described the clinicopathological features of 13 new cases and tested five prognostic algorithms in a total of 67 cases of gynaecological PEComa. Receiver operating characteristic curves were constructed and areas under the curve (AUCs) were calculated to evaluate predictive accuracy. The modified gynaecological-specific algorithm showed high sensitivity and specificity and yielded the highest AUC (0.864). It's earlier version, the gynaecological-specific algorithm, suffered from lower specificity (AUC = 0.843). The post-hoc McNemar test confirmed significant differences between the performances of the modified gynaecological-specific algorithm and the gynaecological-specific algorithm (P = 0.008). The original Folpe algorithm for PEComas of all sites showed low specificity, had a lower AUC (0.591), and was inapplicable in 18% of cases. Its two later versions (the revised Folpe algorithm and the modified Folpe algorithm) also yielded lower AUCs (0.690 and 0.591, respectively).

CONCLUSION

We have shown that the modified gynaecological-specific algorithm predicts the clinical outcome of gynaecological PEComa with high accuracy, and have validated its use for prognostic stratification of gynaecological PEComa.

A Retrospective Case Study of 13 Uterine Perivascular Epithelioid Cell Neoplasm (PEComa) Patients

Introduction and Hypothesis

Perivascular epithelioid cell neoplasms (PEComas) are rare mesenchymal tumors that originate from perivascular epithelioid cells. The uterus is the second most common organ to be affected by PEComa. Most PEComas are benign and the prognosis is usually good. Surgery is the main treatment at present, and adjuvant therapy is mainly used for malignant cases. However, because of the lack of described cases, the best diagnosis and treatment of these tumors cannot be determined.

Methods

From 2009 to 2020, 13 patients from Shengjing Hospital (China Medical University), with uterine PEComa, who met the inclusion criteria and appropriate pathological diagnosis were enrolled in this study. Clinical, pathological, and therapeutic features were retrospectively analyzed to determine the best approach towards diagnosis and treatment.

Results

All the enrolled patients underwent surgical treatment; four of them had a malignant PEComa. Three of the malignant patients received chemotherapy after surgery; among them, one died, another showed no obvious recurrence after regular re-examination, and the third did not undergo any further treatment despite short-term recurrence. However, upon regular re-examination, no progress was observed. The fourth malignant patient did not receive chemotherapy after surgery and showed no obvious recurrence during regular reviews.

Conclusion

The preoperative diagnosis of uterine PEComa lacks specificity and therefore is often confused with uterine leiomyoma or leiomyosarcoma. We conclude that uterine PEComa can be diagnosed by combined analysis of immunohistochemistry and post-operative pathology. Though surgical resection is still the main treatment, high-risk patients can be given adjuvant treatment to strengthen disease control.

Cytopathology of extra-renal perivascular epithelioid cell tumor (PEComa): a series of 7 cases and review of the literature

INTRODUCTION

Perivascular epithelioid cell tumor (PEComa) is a family of rare mesenchymal tumors consisting of histologically and immunohistochemically distinctive perivascular epithelioid cells. Relatively little is known about the cytopathology of extra-renal PEComas. Because of a considerable range of morphology and their rarity, accurate cytologic classification can be challenging. We evaluated cytologic characteristics and diagnostic pitfalls of extra-renal PEComas on fine-needle aspiration (FNA).

MATERIALS AND METHODS

We performed a retrospective search in our cytopathology and surgical pathology database for cases diagnosed as PEComa that had corresponding cytology specimens from 3 medical institutions. All available cytopathology specimens were reviewed. We evaluated cytologic characteristics and recorded histologic diagnoses and immunohistochemical stains.

RESULTS

Seven FNA specimens from 6 patients were identified, and cytologic diagnoses were made in all cases as follows: PEComa (4 cases), most consistent with PEComa (1 case), malignant neoplasm (1 case), and hepatocellular carcinoma (1 case). Most specimens were moderately to highly cellular. Cell distribution occurred as tissue fragments with background proliferating capillaries. Most smears were composed of epithelioid cells showing mild to moderate anisonucleosis, abundant eosinophilic cytoplasm, well-defined borders, intranuclear pseudoinclusions, and prominent nucleoli. A combination of myoid and melanocytic markers was expressed in 6 cases except 1 case, which was called hepatocellular carcinoma.

CONCLUSIONS

This was the largest FNA series for extra-renal PEComas to date. Our study highlights some common cytomorphologic characteristics of PEComa with which cytopathologists should be familiar. In the right clinical and radiologic context, and with the aid of immunohistochemistry, a definitive diagnosis can be achieved.

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.

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.

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.

Perivascular Epithelioid Cell Tumor (Pecoma) in the Transverse Colon of an Adolescent: A Case Report

Perivascular epithelioid cell tumor (PEComa) is defined as a very rare mesenchymal tumor of histologically and immuno-histochemically distinctive perivascular epithelioid cells. PEComa in the colon is very rare, with only a few reported cases so far. Because of its rarity, the clinical features and biological behavior of PEComa in the colon have yet to be established. A 16-year-old female patient with PEComa in the transverse colon was referred to our hospital for rectal bleeding. Laboratory data showed a hemoglobin level of 6.6 g/dL, WBC of 8,800/mm3, and platelet count of 191,000/mm3. Colonoscopy, barium enema, and abdominal computed tomography revealed a 2-cm, smooth-surfaced, round tumor with focal ulceration in the proximal transverse colon. The patient complained of abdominal pain one day after endoscopic polypectomy. She underwent a segmental resection for a perforated transverse colon. Immunohistochemically, the tumor cells showed strong diffuse positivity for HMB-45 while they were negative for c-kit, smooth muscle actin, cytokeratin, S-100, vimentin, desmin, chromogranin, synaptophysin, EMA, and CD-34. The diagnosis of PEComa was based on histological and immunohistochemical staining. The patient did not receive any adjuvant therapy and was discharged on postoperative day 11 without complications. Whole-body fluorine-18 fluorodeoxyglucose fusion positron emission tomography performed 2 months after surgery showed no signs of recurrence or metastasis. There was also no recurrence or metastasis at 24 months' follow-up.

Malignant PEComa With Metastatic Disease at Diagnosis and Resistance to Several Chemotherapy Regimens and Targeted Therapy (m-TOR Inhibitor)

Perivascular epithelioid cell tumors (PEComas) are infrequent neoplasms with peculiar myomelanocytic differentiation. The aggressive abdominopelvic variant is rare, with only a small number of published cases. We present an additional case of this unusual variant, which showed an aggressive histologic and clinical behavior with multiple liver metastases and resistance to several therapies. We also discuss the histological and immunohistochemical profiles as well as the differential diagnosis.

Predicting the Behavior of Perivascular Epithelioid Cell Tumors of the Uterine Corpus

Perivascular epithelioid cell tumors (PEComas) are rare neoplasms that share phenotypic features with angiomyolipomas, clear cell sugar tumors, and lymphangioleiomyomatosis. They presumably represent the neoplastic counterpart of a yet-unidentified perivascular epithelioid cell that expresses smooth muscle and melanocytic immunomarkers. The uterus is the second most common site of origin for perivascular epithelioid cell tumors, after the retroperitoneum. Although most uterine perivascular epithelioid cell tumors are clinically benign and can be cured by a complete surgical excision, there is a subset characterized by both local and distant dissemination. Unfortunately, no single histopathologic or immunohistochemical parameter can accurately predict the clinical behavior of these tumors, which is why the 2012 World Health Organization classification of tumors of the female reproductive organs suggests the use of several criteria to predict the risk of aggressive clinical behavior. Here we review those perivascular epithelioid cell tumors of the uterine corpus with aggressive clinical behavior reported in the literature, and we discuss their most relevant clinical and histopathologic features.

A Case of Malignant PEComa of the Uterus Associated with Intramural Leiomyoma and Endometrial Carcinoma

Perivascular epithelioid cell tumors (PEComas) refers to a family of mesenchymal neoplasms composed of angiomyolipomas, clear cell “sugar” tumors of the lung, and lymphangioleiomyomatoses. These tumors have a distinctive and common component of perivascular epithelioid cells that show an association with blood vessel walls and immunohistochemically display myomelanocytic differentiation. The unique neoplasms have been shown to have an expanded range through a variety of case reports, including visceral, intra-abdominal, soft tissue, and bone tumors. The retroperitoneum, abdominopelvic region, and uterus have been reported to be the most common sites. Most PEComas follow a benign course. However, reports of malignant PEComas are increasing. Many papers have described uterine PEComas, but to our knowledge, there have not yet been any reports of a malignant PEComa arising concomitant with another epithelial tumor and mesenchymal tumor. We report herein the case of a 67-year-old woman who experienced a malignant uterine PEComa infiltrating a preexisting intramural leiomyoma with synchronous well differentiated endometrial carcinoma and multiple liver and lung metastases.

Perivascular Epithelioid Cell Tumor of the Uterus with Ovarian Involvement: A Case Report and Review of the Literature

Patient: Female, 61

Final Diagnosis: Uterine PEComa with ovarian involvement

Symptoms: Palpable abdominal mass

Medication: —

Clinical Procedure: Hysterectomy and bilateral salpingo-oophorectomy

Specialty: Obstetrics and Gynecology

Pancreatic perivascular epithelioid cell tumor: A case report with clinicopathological features and a literature review

Perivascular epithelioid cell tumor (PEComa) of the pancreas is an unusual tumor deriving from mesenchyma. This paper described a case of pancreatic PEComa, which was initially suspected as neuroendocrine carcinoma by biopsy, and therefore surgical treatment was recommended due to undetermined diagnosis. Examination of the surgical specimen under a microscope showed that the tumor cell’s morphology was epithelioid or spindle-shaped, and ranged in a nested pattern. Additionally, these cells had a large extent of acidophilic cytoplasm, no mitotic figures, and expressed HMB-45, melan-p, and smooth muscle actin immunohistochemically. Pathological examination indicated that PEComa originated from the pancreas, but symptoms related to tuberous sclerosis were absent. Since PEComa is extremely rare in the pancreas, it is likely to be ignored in differential diagnosis. In conclusion, our article highlighted the clinicopathological features of PEComa, and we conducted a literature review focusing on PEComa so as to deepen the understanding of this tumor type.

Do patients with tuberous sclerosis complex have an increased risk for malignancies?

Tuberous Sclerosis Complex (TSC) is generally characterized by the presence of benign tumors, but some patients with malignancies have been reported in the literature. We examined a large Italian TSC population (240 individuals followed from 2001 to 2015, aged 3 months-74 years), assessing the frequency of malignancies to determine whether there is an increased risk for cancer in this disorder, and looking for possible features associated with the development of neoplasia. Fifteen patients had malignancies (6.25%); median age at diagnosis was 37.5 years (range of 1.6-58). Five of seven renal tumors were renal cell carcinomas. Eight patients had a non-renal malignancy (3.3%), but we did not find a more prevalent type of cancer. No patient developed more than one malignancy. The prevalence of all malignant tumors was compatible with the prevalence in the general population (5.6%, 95%CI 2.99-9.31%, vs. 4.4% in Italy). Median age at cancer diagnosis was lower (37.5 years, 95%CI 28.6-44.7, vs. 66.0 years). Two patients (13.3%) died of their cancer, while outcome was favorable in the remaining individuals. Malignant tumors were more frequently diagnosed in patients with mutations in TSC1 when compared to TSC2 and patients with no mutation identified (P = 0.032). Our study demonstrated that TSC patients do not seem to have an increased risk for malignancies besides renal cell carcinoma. However, when cancer develops, age at diagnosis is lower than in the general population, and malignant tumors are more frequently diagnosed in patients with mutations in TSC1. Further studies are needed to confirm these data. ©2016 Wiley Periodicals, Inc.

Cutaneous perivascular epithelioid cell tumors: A review on an infrequent neoplasm

“Perivascular epithelioid cutaneous” cell tumors (PEComa) are a family of mesenchymal tumors with shared microscopic and immunohistochemical properties: They exhibit both smooth muscle cell and melanocytic differentiation. Non-neoplastic counterpart of PEComa’s cells are unknown, as well as the relationship between extracutaneous PEComa and primary cutaneous ones. We will review the clinical setting, histopathologic features, chromosomal abnormalities, differential diagnosis and treatment options for cutaneous PEComa.

PEComa of the terminal ileum mesentery as a secondary tumour in an adult survivor of embryonal rhabdomyosarcoma

Perivascular epithelioid cell tumours (pecomas) are rare mesenchymal tumours that are characterized by perivascular epithelioid cell differentiation and immunoreactivity to myogenic and melanocytic markers. These tumours can be classified as benign, uncertain malignant potential, or malignant. Because of the rarity of pecomas, their cause and clinical prognosis remain unclear. To the best of our knowledge, no reports in the literature describe a pecoma of the terminal ileum mesentery as a secondary tumour in an adult survivor of childhood embryonal rhabdomyosarcoma, let alone any childhood cancer. Here, we present the case of a 27-year-old man with a pecoma involving the mesentery of the terminal ileum. At the age of 5, he had been treated with a combination of chemotherapy and high-dose pelvic radiation therapy for embryonal rhabdomyosarcoma, most likely arising from the posterior bladder wall. During routine follow-up 22 years after this patient's initial treatment, computed tomography imaging revealed a mass within the terminal ileum mesentery. The tumour was successfully treated with surgical resection, and pathology examination determined the mass to be a pecoma with uncertain malignant potential. This first case of a pecoma of the terminal ileum mesentery arising within a high-dose radiation therapy field as a secondary tumour in an adult survivor of childhood cancer highlights the importance of screening and surveillance in high-risk childhood cancer survivors treated with high-dose radiation therapy. Further research to build a better understanding of this remarkably rare tumour is warranted.

PEComa: morphology and genetics of a complex tumor family

Perivascular epithelioid cell tumors, or PEComas, are mesenchymal neoplasms composed of histologically and immunohistochemically distinctive epithelioid or spindle cells, which are immunoreactive for both smooth muscle and melanocytic markers. The cells in PEComas are typically arranged around blood vessels and appear to form the vessel wall, often infiltrating the smooth muscle of small- to medium-sized vessels. Periluminal cells are usually epithelioid and the more peripheral cells are spindle shaped. The cells have small, round to oval nuclei, sometimes with focal nuclear atypia, and clear to eosinophilic cytoplasm, and no counterpart normal cell has been identified. The PEComa "family" now includes angiomyolipoma, pulmonary clear cell "sugar" tumor and lymphangioleiomyomatosis, primary extrapulmonary sugar tumor, clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres, abdominopelvic sarcoma of perivascular epithelioid cells, and other tumors with similar features at various sites that are simply termed PEComa. Some PEComas occur in patients with tuberous sclerosis complex and share the genetic abnormalities. There is a behavioral spectrum from benign to frankly malignant, and histologic criteria have been proposed for assessing malignant potential. The differential diagnosis can include carcinomas, smooth muscle tumors, other clear cell neoplasms, and adipocytic tumors. PEComas constitute a genetically diverse group that includes neoplasms harboring TFE3 gene rearrangements and those with TSC2 mutations, indicating alternative tumorigenic pathways. Recent advances in therapy of malignant PEComas relate to increased knowledge of specific genetic changes and their effects on metabolic pathways that are susceptible to specific interventions. We review PEComas, emphasizing the diagnostic spectrum and recent immunohistochemical and genetic findings.

Perivascular epithelioid tumours (PEComas) of the gynaecological tract

Perivascular epithelioid tumours (PEComas) of the gynaecological tract are rare tumours which were first recognised and diagnosed within the last 20 years. They represent a unique diagnostic challenge with regard to their accurate and reproducible distinction from more common entities such as smooth muscle tumours of the uterine corpus. In this review article, we trace the development of the concept of the PEComa tumour family, highlight what is known about extra-gynaecological tract PEComa at an immunohistochemical, molecular and therapeutic level and then present a summary of all reported cases of gynaecological tract PEComa to date. In the summary, we highlight rare subtypes of gynaecological tract PEComa and compare the performances of extant prognostic classification systems for malignancy in these tumours.

Forty-three-year-old woman with mediastinal PEComa treated with chemoradiation therapy

The rarity of PEComa tumours has precluded any clinical trials, but surgery remains the most commonly reported treatment modality with just a few reports on treatment plans involving chemoradiation. We describe a patient with a mediastinal PEComa who presented with symptoms concerning for superior vena cava syndrome. She was deemed inoperable and was thus treated exclusively with chemoradiation therapy. The use of chemoradiation in the treatment of PEComa tumours is reviewed.

[Intra-abdominal soft tissue tumors. What needs to be known to reach the diagnosis with the help of immunohistochemistry, FISH and molecular biology]

Connective tissue tumors located inside the abdomen are a rare heterogeneous group of tumors, except for gastro-intestinal stromal tumors. They may be benign, malignant, or intermediate in terms of biologic potential. Pathologists have to remember the list of all the lesions possibly involved, with their immunohistochemical characteristics, and to know which molecular analyses are needed, with which expected results, and by which team they can be performed. The main tumor types are discussed with diagnostic tools and treatment consequences.

Imaging features of primary and metastatic malignant perivascular epithelioid cell tumors

OBJECTIVE

The objective of our study was to describe the imaging features of primary and metastatic malignant perivascular epithelioid cell tumors (PEComas).

MATERIALS AND METHODS

In this retrospective study, 36 patients (26 women, 10 men; mean age, 53.1 years; age range, 35-77 years) with a histopathologically confirmed diagnosis of malignant PEComa who were seen at our institute between January 2007 and December 2012 were included. Pretreatment imaging of the primary tumor in 17 patients (CT, n = 13; MRI, n = 9; ultrasound, n = 5) and follow-up imaging in all 36 patients (CT, n = 36; MRI, n = 7) were reviewed by three radiologists in consensus.

RESULTS

The most common site of presentation of malignant PEComas was the retroperitoneum (38.9%) followed by the female genital tract (27.8%). Kidneys (8/36) and uterus (8/36) were the organs most frequently involved. The mean largest dimension was 11.01 cm (range, 4.5-25 cm). Primary tumors were well-circumscribed masses (16/17), were heteroechoic on ultrasound (5/5), were hypodense (2/6) to isodense (4/6) enhanced significantly (11/12) and compared with the paraspinal muscles on CT, were hypointense to isointense compared with skeletal muscle on T1-weighted imaging (8/9), were heterogeneously hyperintense compared with skeletal muscle on T2-weighted imaging (9/9), and showed significant post-gadolinium enhancement (7/7) on MRI. Of the 17 primary tumors, necrosis was seen in seven tumors, hemorrhage in three tumors, and calcification in three tumors. Twenty-six of 36 (72%) patients developed metastases, most commonly to the lung (21.6%), liver (17.6%), and peritoneum (10.8%).

CONCLUSION

Malignant PEComas in our study were large tumors that most often arise in the kidneys and uterus and metastasize to lungs, liver, or peritoneum. In our experience malignant PEComas should be considered in the differential diagnosis of large well-circumscribed renal and uterine tumors.

Neoadjuvant sirolimus for a large hepatic perivascular epithelioid cell tumor (PEComa)

Perivascular epithelioid cell tumors (PEComas) are rare soft-tissue tumors with an extremely heterogeneous clinical behavior. They may arise in different organs and may behave indolently or sometimes metastasize with different grades of biological aggressiveness. We report the case of a young woman with a primary inoperable PEComa of the liver with malignant histological features. Since the mTOR pathway is often altered in PEComas and responses have been reported with mTOR-inhibitors such as sirolimus or temsirolimus, we decided to start a neoadjuvant treatment with sirolimus. The patient tolerated the treatment fairly well and after 8 months a favorable tumor shrinkage was obtained. The patient then stopped sirolimus and 2 weeks later underwent partial liver resection, with complete clinical recovery and normal liver function. The histological report confirmed a malignant PEComa with vascular invasion and negative margins. Then 6 additional months of post-operative sirolimus treatment were administered, followed by regular radiological follow-up. For patients with a large and histologically aggressive PEComa, we think that neoadjuvant treatment with mTOR-inhibitor sirolimus may be considered to facilitate surgery and allow early control of a potentially metastatic disease. For selected high-risk patients, the option of adjuvant treatment may be discussed.

Bladder perivascular epithelioid cell tumours

Perivascular epithelioid cell tumours, better known as PECOMAs, are a very uncommon pathological finding. In English medical literature it has rarely been reported. In the genitourinary system, mostly urinary bladder, the incidence is as low as 10 cases described since 2003 until now. In this case report, we present a urinary bladder PECOMA with a detailed pathological description and a review of literature.

Incidental perivascular epithelioid cell tumor in an inguinal hernia sac

Perivascular epithelioid tumors (PEComa) are uncommon mesenchymal neoplasms demonstrating positivity for muscular and melanocytic immuno-markers. Included in this category are angiomyolipoma, lymphangioleiomyomatosis, and clear cell sugar tumors. Lesions which do not fit into these categories are classified as "not otherwise specified". We present a case of an incidentally discovered PEComa within inguinal hernia sac contents in a 70-year-old woman. It consisted of spindled and epithelioid cells with bland oval nuclei, small nucleoli and clear to light eosinophilic cytoplasm. There was no atypia or mitoses. The lesion was strongly positive for HMB45 and smooth muscle actin. Pelvic soft tissue and peritoneal PEComas are rarely reported in literature and very little is known about their prognosis. We discuss the immunohistochemistry, differential diagnosis, and pathogenesis of PEComas.

Perivascular epithelioid cell tumor located retroperitoneally with pulmonary lymphangioleiomyomatosis: report of a case

Perivascular epithelioid cell neoplasms, also known as "PEComas", are unusual mesenchymal tumors, exhibiting perivascular epithelioid cell differentiation and characterized by a mixed myogenic and melanocytic phenotype. "PEComas not otherwise specified" (PEComas-NOS) are especially rare; consequently, there are no published large series, but only case reports. These tumors are rarely located retroperitoneally, with only about 15 such cases reported. We report a case of pulmonary diffuse lymphangioleiomyomatosis with large retroperitoneal PEComa-NOS in a 66-year-old woman. Treatment consisted only of tumor resection, without additional adjuvant therapy. We emphasize the importance of correct immunohistochemistry diagnosis, initiation of recommended treatment, and surveillance of this unique family of tumors.

Perivascular epithelioid cell tumor of male pelvic cavity: a case report and literature review

Perivascular epithelioid cell tumors (PEComas) are a family of rare mesenchymal neoplasms. The PEComas, composed of epithelioid and spindle cells, have the same cellular and immunohistochemical features but are found in different visceral and soft tissue sites. Here, we report the histological and immunohistochemical features of one case of PEComa restricted in the pelvic visceral peritoneum of a male patient. The patient was treated with radical surgery, and was well and on follow-up visits without tumor recurrence.

Perivascular epithelioid cell neoplasm of the urinary bladder in an adolescent: a case report and review of the literature

Abstract

Perivascular epithelioid cell neoplasms (PEComas) of the urinary bladder are extremely rare and the published cases were comprised predominantly of middle-aged patients. Herein, the authors present the first urinary bladder PEComa occurring in an adolescent. This 16-year-old Chinese girl present with a 3-year history of abdominal discomfort and a solid mass was documented in the urinary bladder by ultrasonography. Two years later, at the age of 18, the patient underwent transurethral resection of the bladder tumor. Microscopically, the tumor was composed of spindled cells mixed with epithelioid cells. Immunohistochemically, the tumor were strongly positive for HMB45, smooth muscle actin, muscle-specific actin, and H-caldesmon. Fluorescence in situ hybridization analysis revealed no evidence of EWSR1 gene rearrangement. The patient had been in a good status without evidence of recurrence 13 months after surgery. Urinary bladder PEComa is an extremely rare neoplasm and seems occur predominantly in middle-aged patients. However, this peculiar lesion can develop in pediatric population and therefore it should be rigorously distinguished from their mimickers.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1870004378817301

[A case of a perivascular epithelioid cell tumor mimicking colon cancer]

Perivascular epithelioid cell tumor (PEComa) is extremely rare, which originated from mesenchymal cells in the intestine, and composed of histologically and immunohistochemically distinctive perivascular epithelioid cells. We report here on a case of PEComa in the sigmoid colon. A 62-year-old woman presented with hematochzia 10 days ago. Her abdominal computed tomography scan showed a 5 cm sized intraluminal fungating heterogeneously enhanced, high density mass, which infiltrated pericolic tissue surrounding the sigmoid colon. Colonoscopy showed a purple colored polypoid mass with lobulating contour in the sigmoid colon. She underwent laparoscopic anterior resection. On the histologic examination, the tumor consisted of polygonal epithelioid cells with sheet-like growth of nests, which looked like alveolar tissues in lung. The tumor cells were strongly positive stained with human melanoma black-45 (HMB-45). Pathologic examination was compatible with PEComa. Sixteen months after surgery, she did well without tumor recurrence after surgery. We review the literatures concerning PEComa of the intestine focusing on endoscopic findings.

Melanotic xp11.2 neoplasm of the ovary: report of a unique case

We describe a primary ovarian neoplasm, occurring in a 15-year-old female patient, with morphologic, immunohistochemical, and molecular genetic features identical to those of the very rare tumors of the kidney previously described as "melanotic Xp11 translocation renal cancer." This represents, to the best of our knowledge, the first report of a melanotic Xp11 translocation-associated neoplasm arising outside of the kidney. We discuss the relationship of these rare tumors to neoplasms showing perivascular epithelioid cell differentiation, in particular those showing TFE3 rearrangements.

Retroperitoneal masses mimicking adrenal tumors

OBJECTIVE

To report 10 cases of neoplasms that were initially thought to be primarily adrenal-derived masses but were later confirmed as tumors of a different origin.

METHODS

Between 2000 and 2011, a total of 229 patients underwent adrenalectomy at our institution. Of this overall group, 10 patients had retroperitoneal pathologic conditions mimicking adrenal tumors. Using an institutional review board-approved database, we reviewed the clinical, biochemical, and radiologic characteristics of these 10 patients.

RESULTS

The study cohort consisted of 4 male and 6 female patients. The mean age of these 10 patients was 48 years. The pathologic conditions included schwannoma (n = 3), leiomyosarcoma (n = 2), and 1 each of metastatic angiosarcoma, metastatic granulosa cell tumor, retroperitoneal hematoma, perivascular epithelioid cell tumor, and bronchogenic cyst. The patient with angiosarcoma had elevated plasma and urine catecholamines and a positive metaiodobenzylguanidine scan, whereas the others had normal findings on biochemical work-up. A percutaneous biopsy was performed preoperatively in 2 patients. All patients, except the patient with hematoma, underwent abdominal exploration, which was laparoscopic in 5, open in 2, and robotic in 2. With exclusion of the patients with angiosarcoma and hematoma, resection was possible in all the remaining patients.

CONCLUSION

In this report we describe our experience with retroperitoneal masses mimicking adrenal tumors. Increased awareness of these unusual pathologic conditions is important for appropriate clinical management of these tumors. The presentation of the patients and the surgical management of these individual pathologic entities are highlighted.

Cardiac Epithelioid PEComa: Report of Two Cases and Review of the Literature

Cardiac PEComa is very rare. We reported two cases of epithelioid PEComas, one in an adult and one in a 2-year-old child. Both tumors were composed of sheets of epithelioid cells with coagulation necrosis. In addition, the adult case showed marked nuclear atypia and high mitotic activity with atypical mitosis and the pediatric case showed unusual clear cell features. Immunohistochemically, both tumors were positive for HMB-45 and SMA and negative for S100 and cytokeratin. Electron microscopy was performed in the pediatric case and showed premelanosomes. The adult patient developed extensive metastasis indicating malignant behavior. Prior to the two cases, only 5 other cases of cardiac PEComa were reported and the literatures are reviewed.

Malignant perivascular epithelioid cell tumor of the esophagus

Malignant perivascular epithelioid cell tumor (PEComa) is a rare tumor composed of hybrid tumor cells characterized by immunoreactivity for both melanocytic and smooth muscle markers. This paper describes the uncommon esophageal location of an 8 cm PEComa in a 75-year-old Caucasian man who was presented with ingravescent dysphagia. Although PEComas arising within the gastrointestinal tract are exceptional findings, clinicians should not exclude this class of tumors in the diagnostic investigation of a bulky lesion of the esophageal wall.

Soft tissue tumors of uncertain origin

Many soft tissue tumors of childhood lack obvious differentiation toward a defined mesenchymal tissue type or have a phenotype that does not correspond to any defined normal tissue. These challenging tumors are currently regarded as neoplasms of uncertain differentiation. Nonetheless, there have been great strides in the understanding of their pathologic and genetic features and biologic underpinnings. The application of new genetic information to the pathologic diagnosis among this group of tumors is an emerging area in diagnostic pediatric pathology. This article reviews the clinicopathologic features of tumors of uncertain and/or miscellaneous origin, with an emphasis on the unique aspects of these neoplasms in children and adolescents, use of diagnostic adjuncts, and differential diagnosis.

Malignant perivascular epithelioid cell tumor in children: description of a case and review of the literature

Perivascular epithelioid cell tumors (PEComas) include different morphological entities originating from perivascular epithelioid cells. Their clinical behavior is not predictable, and there are no strict histologic criteria for malignancy, although larger tumors with infiltrative growth, hypercellularity, cellular atypia, atypical mitoses, and necrosis generally have a malignant course. Pediatric PEComas are rare, with less than 40 cases reported, mostly in children older than 5 years. We describe a case of malignant PEComa of the ligamentum teres in a 2-year-old girl, characterized by the occurrence of local relapse after primary treatment with chemotherapy and surgery and poor response to imatinib mesilate and temsirolimus used after further analyses confirmed p70S6K expression involved in the mTOR pathway. The girl was eventually treated with a debulking surgical procedure and is now alive with disease 6 years after diagnosis. Literature data of children affected by PEComas were also analyzed, trying to identify pathologic characteristics that could predict their course and therapeutic options. Histologically, they may be differentiated in 3 prognostic categories: (1) benign, lacking unfavorable morphological markers; (2) with uncertain malignant potential, carrying 1 unfavorable marker; and (3) malignant, with at least 2 unfavorable markers. In the literature, 9% of cases occurred as a second malignancy probably because of genomic instability related to treatment. Their different biology and the potential value of targeted therapies remain to be explored. The indolent evolution in our patient was similar to that reported in some other cases in the literature. In terms of treatment, the present case suggests a minor response to temsirolimus compared with the adult population.

"Malignant" perivascular epithelioid cell neoplasm: risk stratification and treatment strategies

Purpose. Perivascular epithelioid cell tumors (PEComas) are a rare collection of tumors characterized by a myomelanocytic phenotype, and PEComas occurring in “nonclassic” anatomic distributions are known as perivascular epithelioid cell tumor not otherwise specified (PEComa-NOS). This review aims to compile and analyze cases of PEComa-NOS in an effort to better define their natural history. Design. We evaluated all 234 cases of PEComa-NOS reported in the English literature, extracting information regarding diagnostic features, treatment approaches, and outcomes. Multivariate analysis of a number of variables evaluable on pathologic review was performed to refine preexisting risk stratification criteria. Outcomes for patients receiving nonsurgical treatment are also reported. Results. Primary tumor size ≥5 cm (P = 0.02) and a high (1/50 HPF) mitotic rate (P < 0.0001) were the only factors significantly associated with recurrence following surgical resection. Cytotoxic chemotherapy and radiation therapy have shown little benefit in treating PEComa-NOS; mTOR inhibition is emerging as a treatment option. Conclusion. Progress has been made in understanding the natural history and molecular biology of PEComa-NOS. This review further clarifies risk of recurrence in this disease, allowing clinicians to better risk stratify patients. Further work should focus on applying this knowledge to making treatment decisions for patients with this disease.

Malignant pigmented clear cell epithelioid cell tumor (PEComa) in an adolescent boy with widespread metastases: a rare entity in this age group

Malignant pigmented clear cell epithelioid cell tumor of the kidney is a rare variant of perivascular epithelioid cells tumors (PEComa) or epithelioid angiomyolipoma (AML). PEComa is characteristically composed purely of epitheloid cells. The fat cells and the blood vessels that are typical of classic AML are absent. Most epithelioid AML cases are benign; however, malignant epithelioid AML of the kidney has been occasionally reported in adults in association with tuberous sclerosis. We report the radiological-pathological features of a malignant pigmented clear cell epithelioid renal tumor in a 15-year-old boy presenting with extensive metastases but without clinical evidence of tuberous sclerosis.

Primary malignant gastric PEComa - Diagnostic and technical dilemmas

INTRODUCTION

The World Health Organisation defines PEComa's as "a mesenchymal tumour composed of histologically and immunohistochemically distinctive perivascular cells".(1) These ubiquitous tumours show distinctive perivascular epithelioid cell differentiation and arise most commonly at visceral and abdominopelvic sites.

PRESENTATION OF CASE

We present a case of a forty-two year old man presenting to accident and emergency department with upper gastro-intestinal bleeding. He had a palpable epigatric mass on examination. He underwent a CT Scan Abdomen which displayed a tumour arising from the gastric wall. Upper GI endoscopy and biopsy was carried out and biopsied were taken for histological analysis. A primary gastric PEComa was diagnosed and the patient underwent distal polya gastrectomy and gastrojejunostomy. This is believed to be the first reported case of a Primary malignant gastric PEComa.

DISCUSSION

Perivascular epithelioid carcinomas were first described in 1943 as an abnormal myoblast in a case of renal angiomyolipoma. PEComas display a strong female predominance with a typical benign course. There are approximately 100 reported cases of PEComa to date, with 55 of which were malignant. PEComa's may be subdivided into benign, uncertain malignant potential and malignant. Their natural history can be very aggressive leading to multiple metastases and death as expected with a high-grade sarcoma.

CONCLUSION

This case depicts the aggressive nature of malignant gastric PEComa's. The majority of PEComa's are benign in nature and have a better prognosis. We display here the challenges in ascertaining a definitive diagnosis and management of such patients due to limited clinical studies.