TFE3 activation in a TSC1-altered malignant PEComa: challenging the dichotomy of the underlying pathogenic mechanisms.

Perivascular epithelioid cell tumors (PEComas) form a family of rare mesenchymal neoplasms that typically display myomelanocytic differentiation. Upregulation of mTOR signaling due the inactivation of TSC1/2 (Tuberous Sclerosis 1 and 2) is believed to be a key oncogenic driver in this disease. Recently, a subgroup of PEComas harboring TFE3 (Transcription Factor E3) rearrangements and presenting with a distinctive morphology has been identified. TSC1/2 and TFE3 aberrations are deemed to be mutually exclusive in PEComa, with two different pathogenic mechanisms assumed to lead to tumorigenesis. Here, we challenge this dichotomy by presenting a case of a clinically aggressive TCS1-mutated PEComa displaying a TFE3-altered phenotype. FISH analysis was suggestive of a TFE3 inversion; however, RNA and whole genome sequencing was ultimately unable to identify a fusion involving the gene. However, a copy number increase of the chromosomal region encompassing TFE3 was detected and transcriptome analysis confirmed upregulation of TFE3, which was also seen at the protein level. Therefore, we believe that the TSC1/2-mTOR pathway and TFE3 overexpression can simultaneously contribute to tumorigenesis in PEComa. Our comprehensive genetic analyses add to the understanding of the complex pathogenic mechanisms underlying PEComa and harbor insights for clinical treatment options.

Successful management of perivascular epithelioid cell tumor of the rectum with recurrent liver metastases: A case report.

RATIONALE: The perivascular epithelioid cell tumor (PEComa) is rare in young man and rarely occurs in the large intestine. PATIENT CONCERNS: The clinical characteristics, diagnosis, and managements in a 28-year-old boy who presented with sudden onset of cramping and abdominal pain and intermittent melena with a blood pressure of 74/39 mm Hg was retrospectively reviewed. CT scan of the abdomen revealed a 8.9 × 7.2 cm mass in the pelvic floor. DIAGNOSES: Given the difficulty of obtaining a diagnostic specimen, surgical resection was performed. The pathology report of lower anterior resection was malignant PEComa of the rectum in 2006. INTERVENTIONS: Treatment consisted of surgical resection only without additional adjuvant therapy. Over the next 49 months (until 2010) after surgery, abdominal CT showed a 0.6-cm hypodense mass over the liver with suspected liver metastasis. He refused any further evaluation and treatment. After 4 years (2014), abdominal CT showed that the original mass had increased from 0.6 to 1.5 cm and the number of tumors had increased from 1 to 3. In August 2014, he underwent a metastatic hepatectomy without additional chemotherapy or radiotherapy. OUTCOMES: We noted that the metastatic progression was slow in the 4 years after the first operation. At 28 months after metastatic hepatectomy, the patient was doing well. There was also no recurrence of the PEComa of the rectum at the 120-month follow-up in 2016. LESSONS: To the best of our knowledge, this is the first report of a PEComa of the rectum with liver metastases treated with only surgical resection. At approximately 8.8 cm, this is the largest PEComa of the rectum reported in the recent literature.

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

BACKGROUND: Perivascular epithelioid cell tumors (PEComas) are a rare group of neoplasms composed of epithelioid cells that express both melanocytic and myoid markers. When considering PEComas of the female genital tract, the uterus is the most common location. Involvement of the ovary in the context of a primary uterine PEComa, in the absence of systemic disease associated with tuberous sclerosis, however, has only been reported in 1 previous case. CASE REPORT: We report a case of a PEComa of the uterus with metastasis to the left ovary in a 61-year-old Caucasian woman. Gross examination of the uterus revealed a 10.7×10.5×10.2 cm tan-brown, mostly solid, partially cystic mass. Microscopic examination showed epithelioid cells with clear to eosinophilic cytoplasm, arranged in fascicles. Intranuclear pseudoinclusions were also noted. The tumor cells were smooth muscle actin, caldesmon, and desmin positive (diffuse); HMB-45 positive (focal); and Melan-A, AE1/AE3, CD10, and S100 negative by immunohistochemistry. CONCLUSIONS: Distinguishing among mesenchymal neoplasms, including PEComas, endometrial stromal sarcomas, and leiomyosarcomas, can be difficult. Careful analysis of morphologic and immunohistochemical features is of the utmost importance. Differential diagnosis, including morphologic features and immunohistochemical patterns, is also discussed.

Malignant perivascular epithelioid cell tumor (PEComa) of the femur: a case report and literature review.

BACKGROUND: We describe a case of malignant perivascular epithelial cell tumor (PEComa) arising primarily in the distal left femur of a 47-year-old male. CASE PRESENTATION: The patient presented with pain accompanied by progressive swelling of his left thigh. Computed tomography (CT) scan and magnetic resonance imaging (MRI) revealed an osteolytic lesion. Curettage of the lesion was reported as a clear cell tumor with recommendation for exclusion of a metastatic clear cell carcinoma. However, thorough examinations did not find any primary site elsewhere, apart from the presence of bilateral pulmonary metastases. Evaluation of the submitted H & E slides identified a malignant PEComa which was further confirmed by subsequent immunohistochemical study. CONCLUSIONS: The occurrence of PEComa as a primary bone lesion is extremely rare. We present here a malignant PEComa of the distal left femur, and summarize the clinicopathological characteristics of this rare entity with literature review. VIRTUAL SLIDES: The virtual slide (s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/5729035221600545 .

TFE3 translocation-associated perivascular epithelioid cell neoplasm (PEComa) of the gynecologic tract: morphology, immunophenotype, differential diagnosis.

TFE3 translocation-associated PEComa is a distinct form of perivascular epithelioid cell neoplasm, the features of which are poorly defined owing to their general infrequency and limited prior reports with confirmed rearrangement or fusion. Recent investigation has found a lack of TSC gene mutation in these tumors compared with their nonrearranged counterparts, which underscores the importance of recognizing the translocated variant because of hypothetical ineffectiveness of targeted mTOR inhibitor therapy. Six cases were identified, and TFE3 rearrangement was confirmed by fluorescence in situ hybridization. Patient age ranged from 46 to 66 years (median 50 y), and none had a history of a tuberous sclerosis complex. Three cases arose in the uterine corpus, 1 in the vagina, 1 pelvic tumor, and 1 pulmonary tumor that was likely a recurrence/metastasis from a probable uterine primary. Five cases had clear cell epithelioid morphology that showed a spectrum of atypia, while 1 case had a mixture of clear cell epithelioid and spindle cells. A mostly consistent immunophenotype was observed in the clear cell epithelioid cases: each demonstrated diffuse TFE3, HMB45, cathepsinK labeling, either focal or no melanA staining, and variably weak reactivity to smooth muscle markers. The mixed clear cell epithelioid and spindle cell case had a similar expression pattern in its epithelioid component but strong muscle marker positivity in its spindle cell component. Follow-up ranged from 1 to 57 months. Three cases demonstrated aggressive behavior, and 3 cases had no evidence of recurrence. Both GYN-specific and traditional sets of criteria for malignancy were evaluated. The GYN model showed improved inclusion and specificity in comparison to the traditional model.

Malignant perivascular epithelioid cell tumor of the kidney with rare pulmonary and ileum metastases.

AIMS: To report one case of malignant perivascular epithelioid cell tumor (PEComa) of the kidney with rare pulmonary and ileum metastases and analyze its clinicopathological features. METHODS: We analyzed the clinicopathological features of one case of malignant PEComa of the kidney with pulmonary and ileum metastases. Immunohistochemistry staining was performed. RESULTS: The patient was a 48-year-old man with a renal mass approximately 14 cm × 11 cm × 8 cm in size. Microscopically, the tumor was mainly composed of polygonal epithelioid cells with dense eosinophilic cytoplasm and round nuclei with small nucleoli. Focal tumor cells showed pleomorphism with multinucleated giant cells and prominent nucleoli. The tumor cells nests were surrounded by thick-walled irregular blood vessels. Focal fat cells were found within the tumor. Hemorrhage and coagulative necrosis were also present. The tumor cells were positive for vimentin, HMB45, and Melan-A, and focally positive for SMA and S-100 protein. After 5 years and 5.6 years of nephrectomy, the tumor metastasized to the right lung and ileum, respectively. CONCLUSION: We first reported one case of malignant PEComa of the kidney with pulmonary and ileum metastases. Metastatic PEComa of the lung and ileum should differentiate from primary carcinoma, metastatic carcinoma, malignant melanoma, and gastrointestinal stromal tumor.

Malignant perivascular epithelioid cell tumor (PEComa) of cervix with TFE3 gene rearrangement: a case report.

In this study, we reported the first PEComa arising within the cervix with TFE3 gene rearrangement and aggressive biological behavior. Morphologically, the tumor showed infiltrative growth into the surrounding parenchyma. The majority of tumor cells were arrayed in sheets, alveolar structures, or nests separated by delicate fibrovascular septa. There was marked intratumoral hemorrhage, necrosis, and stromal calcifications. The tumor cells had abundant clear cytoplasm, focally containing finely granular dark brown pigment, morphologically considered to be melanin. Immunohistochemically, the tumor cells demonstrated moderately (2+) or strongly (3+) positive staining for TFE3, HMB45, and Melan A but negative for CKpan, SMA, S100, PAX8, and PAX2. The presence of Ki-67 protein demonstrated a moderate proliferation rate, with a few Ki-67-positive nuclei. Using a recently developed TFE3 split FISH assay, the presence of TFE3 rearrangement was demonstrated. All these clinicopathologic features are suggestive of TFE3-rearranged PEComas of the cervix. Our results both expand the known characteristics of primary cervix PEComas and add to the data regarding TFE3 rearrangement-associated PEComas.

Bone metastases from bladder perivascular epithelioid cell tumor - an unusual localization of a rare tumor: a case report.

INTRODUCTION: Perivascular epithelioid cell tumors are mesenchymal tumors composed of histologically and immunohistochemically distinctive perivascular epithelioid cells. This type of tumor is rare but bladder localization is even rarer. CASE PRESENTATION: A case of bone metastatic bladder perivascular epithelioid cell tumor in a 65-year-old Caucasian man treated with surgery and chemotherapy is described and compared with other reports in the literature. CONCLUSIONS: The rarity of perivascular epithelioid cell tumors hinders the development of a standard therapeutic approach, and thus requires case report descriptions. There is a need for cooperative studies to enlarge the case series and establish the best treatment strategy for this rare disease.

Perivascular epithelioid cell neoplasm (PEComa) of the gynecologic tract: clinicopathologic and immunohistochemical characterization of 16 cases.

Perivascular epithelioid cell tumor (PEComa) belongs to a family of tumors characterized by coexpression of melanocytic and muscle markers. Recent studies have shown that sporadic and tuberous sclerosis complex-associated PEComa may respond to mTOR inhibitors underscoring the importance of recognizing this tumor. However, its occurrence in the gynecologic tract continues to be disputed owing to its common misclassification as other types of uterine sarcoma and its controversial relationship with epithelioid smooth muscle tumors. To more fully characterize PEComa of the female genital tract, 16 cases of gynecologic PEComa were identified (1990 to 2012) and formed the basis of this study. Each case was analyzed for conventional morphologic and immunohistochemical characteristics established for PEComa of extrauterine sites; clinical outcome data were obtained for all cases. The 16 patients were aged 28 to 60 (mean 49; median 50) years, and 1 had a history of tuberous sclerosis complex. Thirteen cases were primary of the uterus, 2 of the adnexa, and 1 of the vagina. Tumor size ranged from 0.3 to 25.0 (mean 8.7) cm. Three patients died of disease, 6 were alive with disease, and 7 were alive without evidence of disease at last follow-up (1 mo to 13 y follow-up; mean 26 mo). All patients with an adverse outcome met established criteria for malignancy as proposed for extrauterine sites (ie, 2 or more features present: size ≥5 cm, high-grade nuclear features, infiltration, necrosis, lymphovascular invasion, or a mitotic rate ≥1/50 high-power fields). Of the melanocytic markers, HMB45 was most commonly expressed (16/16 positive, 100%), followed by microphthalmia transcription factor (11/12 positive, 92%), MelanA (14/16 positive, 88%), and S100 protein (2/10 positive, 20%). Of the smooth muscle markers, desmin was most commonly expressed (15/15 cases, 100%), followed by SMA (14/15 cases, 93%) and h-caldesmon (11/12 cases, 92%). TFE3 immunopositivity was identified in 5 of 13 cases; however, 3 tested cases were negative for a TFE3 rearrangement by fluorescence in situ hybridization. Current criteria for malignancy appear to be valid in the female genital tract, although modified criteria, as described herein, may be more specific. Awareness of the characteristic features of PEComa is important to help distinguish it from epithelioid smooth muscle tumors and other mimics as PEComa may respond to unique chemotherapeutic regimens.

Malignant perivascular epithelioid cell tumor of the retroperitoneum.

Perivascular epithelioid cell tumors (PEComas) are a rare type of mesenchymal neoplasms characterized by a proliferation of perivascular cells with an epithelioid phenotype and expression of myo-melanocytic markers. The majority of PEComas seem to be benign and usually their prognosis is good. Malignant cases are extremely rare, exhibiting a malignant course with local recurrences and distant metastases. We herein report a case of a malignant PEComa arising in the retroperitoneum. The patient was a 55-year-old woman experiencing abdominal discomfort for approximately one month. Ultrasound and computer tomography (CT) scans of the abdomen revealed a solid mass arising from the retroperitoneum. Microscopically, the tumor was composed of epithelioid cells mixed with spindled cells. The nucleus had significant atypia, and the mitoses were obvious. The focal intravascular tumor embolus was visible. Immunohistochemically, the epithelioid tumor cells were positive for HMB45 and Melan-A, and the spindled tumor celLs were positive for SMA and desmin. Seven months after a surgical resection, an ultrasound revealed liver metastases. In conclusion, the malignant PEComas of the retroperitoneum is a very rare neoplasm with unique morphological and immunohistochemical characteristics. It should be differentiated from other epithelioid cell tumors of the retroperitoneum.

Malignant perivascular epithelioid cell tumor of mesentery with lymph node involvement: a case report and review of literature.

Perivascular epithelioid cell tumor (PEComa) is a rare but distinct mesenchymal neoplasm composed of histologically and immunohistochemically unique perivascular epithelioid cells. Due to its relative rarity, little is known about the histogenesis and prognostic factors of this tumor. We describe a case of unusual mesenteric PEComa in a 38-year-old female patient with regional lymph node involvement. Histologically, the tumor was composed of sheet of epithelioid cells with abundant clear or eosinophillic cytoplasms. Extensive coagulative necrosis and a few mitotic figures (2/50 high power field) could be found in tumor. The epithelioid tumor cells were diffusely positive for HMB-45, Melan-A, and focally positive for calponin. One of enlarged mesenteric lymph nodes was observed to be involved by tumor. A diagnosis of malignant mesenteric PEComa with lymph node involvement was made. The patient received chemotherapy after total resection of tumor and segmental resection of involved jejunum. There was no sign of recurrence of tumor found in period of 6-month regular follow-up after chemotherapy. To our knowledge, this is the first case of malignant PEComa in mesentery accompanied with regional lymph node involvement. The literature on this rare tumor is reviewed and diagnostic criteria of malignant PEComa are discussed. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1309992178882788.

PEComa of the colon resistant to sirolimus but responsive to doxorubicin/ifosfamide.

A 23-year-old male presented with a three-week-history of crampy abdominal pain and melaena. Colonoscopy revealed a friable mass filling the entire lumen of the cecum; histologically, it was classified as perivascular epithelioid cell tumor (PEComa). An magnetic resonance imaging scan showed, in addition to the primary tumor, two large mesenteric lymph node metastases and four metastatic lesions in the liver. The patient underwent right hemicolectomy and left hemihepatectomy combined with wedge resections of metastases in the right lobe of the liver, the resection status was R0. Subsequently, the patient was treated with sirolimus. After 4 mo of adjuvant mammalian target of rapamycin inhibition he developed two new liver metastases and a local pelvic recurrence. The visible tumor formations were again excised surgically, this time the resection status was R2 with regard to the pelvic recurrence. The patient was treated with 12 cycles of doxorubicin and ifosfamide under which the disease was stable for 9 mo. The clinical course was then determined by rapid tumor growth in the pelvic cavity. Second line chemotherapy with gemcitabine and docetaxel was ineffective, and the patient died 23 mo after the onset of disease. This case report adds evidence that, in malignant PEComa, the mainstay of treatment is curative surgery. If not achievable, the effects of adjuvant or palliative chemotherapy are unpredictable.

Rare case of uterine PEC-oma (perivascular epithelioid cell tumor) recurrence. Case report and literature review.

Perivascular epithelioid cell tumor (PEC-oma) is a rare mesenchymal neoplasm. Literature reports more than 100 cases of PEC-oma, a third of which is of uterine or uterine retroperitoneum origin. The case of a 59-year-old woman presented here is, to the best of our knowledge, the first described fast uterine PEC-oma recurrence of the tumor of the gastrointestinal tract origin. In this text the authors also present literature review concerning this rare female tumor

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 PEComa of the adrenal gland.

Perivascular epithelioid cell neoplasms, also known as PEComas, are unique mesenchymal tumors exhibiting perivascular epithelioid cell differentiation, characterized by a mixed myogenic and melanocytic phenotype. PEComas arising in visceral organs outside of the kidney, liver, and lung are rare, and often pose problems in diagnosis. Examples of this neoplasm originating in the adrenal gland are limited. The present report details the clinical and pathologic features of an unusual case of a pure epithelioid PEComa (epithelioid angiomyolipoma) of the adrenal gland exhibiting clinically malignant behavior in the form of pulmonary metastases, a feature not previously described in tumors of this site. The diagnosis was supported by immunohistochemical studies demonstrating expression of myoid and melanocytic antigens. The present case serves to emphasize the potential of PEComa for clinically aggressive behavior and the importance of distinguishing this tumor from other epithelioid neoplasms that are more commonly encountered in the adrenal gland.

PEComa presenting in bone: clinicopathologic analysis of 6 cases and literature review.

PEComas other than angiomyolipoma, lymphangioleiomyomatosis, and clear cell sugar tumor of the lung are relatively rare, and PEComas presenting in bone are especially rare. To further characterize their clinicopathologic features, 6 cases of PEComa which first presented in bone were retrieved from the authors' consult and surgical pathology files, including both primary and metastatic lesions. Four patients were female and 2 patients were male. The age at diagnosis ranged from 35 to 71 years, with a mean of 51.5 years. As for the 3 cases known definitely to have arisen in bone, the primary sites were right tibia in 2 cases and thoracic vertebra in 1 case. In the 2 cases, presenting in scapula and femur respectively, the primary sites could not be determined with certainty. In 1 case, the lesion was first found in humerus, but the primary tumor proved to be located in the uterus. Histologically, all the tumors were composed of both epithelioid and spindle cells, showing a nested pattern with elaborate vasculature. The characteristic thin walled vessels around which tumor cells were arranged tightly, or in a radiating fashion were seen in all cases. Two or more worrisome features (tumor size >5 cm, infiltrative growth pattern, high nuclear grade, high cellularity, necrosis, and mitotic activity >1/50 HPF) were identified in 4 cases, of which 2 were primary bone tumors; these cases were classified as "malignant" histologically. We conclude that both the primary and metastatic PEComas can present in bone, although both are rare. Combining our findings with the few earlier published reports, it may be suggested that primary PEComa of bone tends to involve lower extremities (5/7 cases). Histologically, they show similar cytomorphology, nested architecture, and characteristic vessels as PEComas at other sites. In addition, a significant subset of the primary bone lesions seem to be malignant.

Perivascular epithelioid cell tumor of abdominal origin.

Perivascular epithelioid tumor is not a common disease; therefore, large series are not available in the literature, and most are case reports. Histologic characteristics of these neoplasms are positivity to melanogenic (HMB-45) and muscle stains. All these neoplasms have the characteristic perivascular epithelioid cell or "PEC," but the term myomelanocyte tumor has been proposed because of the immunohistochemistry expression. Females are affected more commonly than males. The uterus seems to be one of the most common organs affected. Its clinical behavior is uncertain, and standard treatment has not been established as well as criteria for malignancy. We report 3 cases of abdominal PEComa, 1 of them with benign clinical outcome and 2 with an aggressive behavior.

[Perivascular epithelioid tumors: Utility of the positron emission tomography with 18F-fluorodesoxyglucose (PET-TAC FDG) in their staging and follow-up]. / Tumor epitelioide perivascular uterino. Utilidad de la tomografía por emisión de positrones con (18)F-fluordesoxiglucosa en su estadificación y seguimiento.

Perivascular epithelioid tumors (PEComas) are a rare group of mesenchymal neoplasms with an unpredictable natural history and uncertain malignant potential. Uterine involvement and their association with tuberous sclerosis are typical for these tumors. We present a case of a 40-year old patient who was incidentally diagnosed of a uterine PEComa and serial studies of PET-CT with FDG were performed for staging and therapeutic response assessment. FDG PET-CT proved to be a valuable tool for detecting unsuspected pulmonary metastases and defining the reassessment of the patient after chemotherapy. The findings suggest that since this is a rare tumor, which does not always have benign behaviour, PET-CT may be a useful diagnostic imaging procedure for staging and clinical monitoring of patients who suffer this type of tumors.