Hepatic perivascular epithelioid cell tumors: Benign, malignant, and uncertain malignant potential.

In 2013, the World Health Organization defined perivascular epithelioid cell tumor (PEComa) as "a mesenchymal tumor which shows a local association with vessel walls and usually expresses melanocyte and smooth muscle markers." This generic definition seems to better fit the PEComa family, which includes angiomyolipoma, clear cell sugar tumor of the lung, lymphangioleiomyomatosis, and a group of histologically and immunophenotypically similar tumors that include primary extrapulmonary sugar tumor and clear cell myomelanocytic tumor. Clear cell tumors with this immunophenotypic pattern have also had their malignant variants described. When localizing to the liver, preoperative radiological diagnosis has proven to be very difficult, and most patients have been diagnosed with hepatocellular carcinoma, focal nodular hyperplasia, hemangioma, or hepatic adenoma based on imaging findings. Examples of a malignant variant of the liver have been described. Finally, reports of malignant variants of these lesions have increased in recent years. Therefore, we support the use of the Folpe criteria, which in 2005 established the criteria for categorizing a PEComa as benign, malignant, or of uncertain malignant potential. Although they are not considered ideal, they currently seem to be the best approach and could be used for the categorization of liver tumors.

Solitary Pulmonary Perivascular Epithelial Cell Tumor Mimicking Pulmonary Metastasis on 68 Ga-DOTATATE PET/CT in a Patient With Pancreatic Neuroendocrine Tumor.

ABSTRACT: We report the findings of 68 Ga-DOTATATE PET/CT in a 56-year-old woman with solitary pulmonary perivascular epithelioid cell tumor. 68 Ga-DOTATATE PET/CT showed a lesion with intense uptake in the region of pancreatic head and a solitary nodule with moderate uptake in the left lung. Pancreatic neuroendocrine tumor with pulmonary metastasis was considered. The postoperative pathological results showed a benign perivascular epithelioid cell tumor of the lung. This case emphasizes the need to increase awareness of benign perivascular epithelioid cell tumors in the differential diagnosis of solitary pulmonary nodule with moderate DOTATATE activity.

18 F-FAPI for Imaging Metastatic Perivascular Epithelioid Cell Neoplasm.

ABSTRACT: We compared 18 F-FAPI and 18 F-FDG PET/CT findings of metastatic perivacular epitheliod cell tumor in a 23-year-old woman. Apart from showing strong uptake of a left upper lung mass that showed moderate uptake on 18 F-FDG, 18 F-FAPI PET/CT additionally presented hypermetabolism in diffuse multifocal lesion throughout the body. This case suggests that 18 F-FAPI PET/CT might play a more beneficial role than 18 F-FDG PET/CT in identifying and assessing the extent of perivascular epithelioid cell tumors.

Rare perivascular epithelial cell tumor of the colon 18F-FDG PET/CT imaging: A case report.

RATIONALE: Neoplasms with perivascular epithelioid cell differentiation (PEComas) are mesenchymal tumors that rarely occur in the colon. Here, we report the occurrence of a malignant PEcoma in the colon using 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). PATIENT CONCERNS: A 55-year-old woman was admitted to the hospital with abdominal pain for 10 days and a self-induced abdominal mass for 3 days. 18F-FDG PET/CT imaging showed a large hypermetabolic nodule and mass in the right mid-upper abdomen with heterogeneous density and a further increase in metabolism on the delayed scan. DIAGNOSES: PEComa of the colon. INTERVENTIONS: Tumor resection was performed. OUTCOMES: The patient is well after 2 months of treatment, pending further follow-up. LESSONS: Malignant perivascular epithelioid cell tumors originating in the colon are extremely rare, and our report suggests that PEComa should be considered as a differential diagnosis for 18F-FDG gastrointestinal malignancies. Additionally, 18F-FDG PET/CT may play a key role in the staging and extent of lesions in intestinal malignancies.

Perivascular epithelioid cell tumor (PEComa) of the liver. An extremely rare diagnosis.

Hepatic PEComa are tumors that show perivascular epithelioid cell differentiation. Scarcely published, its management is based on small case series and currently its treatment of choice is surgical resection. We present a clinical case of a 74-year-old woman who underwent surgery at our hospital for a benign hepatic PEComa.

Transurethral en bloc resection of a bladder perivascular epithelioid cell tumor (PEComa): a case report.

BACKGROUND: Perivascular epithelioid cell tumor (PEComa) is a mesenchymal tumor with distinct histologic and immunologic features. PEComas that originate in the bladder are extremely rare clinically, with only 35 cases reported in the English literature thus far. Here, we report a case of bladder PEComa resection by transurethral en bloc resection of bladder tumor (ERBT). CASE PRESENTATION: A 66-year-old female with a history of poorly controlled type 2 diabetes with associated complications of frequent urinary tract infections presented to our hospital for a routine physical examination. Outpatient ultrasound examination revealed a strong echogenic mass of approximately 1.5 × 1.3 × 1.3 cm in size on the posterior wall of the bladder. The enhanced computed tomography and enhanced magnetic resonance imaging after admission both suggested a well-defined isolated nodular mass on the posterior wall of the bladder with significant enhancement on the enhanced scan. The tumor was successfully and completely resected by ERBT. Postoperative pathological examination and immunohistochemical results confirmed the mass was a bladder PEComa. No tumor recurrence was observed in the six-month postoperative follow-up. CONCLUSION: Bladder PEComa is an extremely rare mesenchymal tumor of the urinary system. When imaging and cystoscopy reveal a nodular mass with an abundant blood supply in the bladder, PEComa should be included in the differential diagnosis of bladder tumors. Surgical resection is currently the primary option for the treatment of bladder PEComa. For a solitary, pedunculated, narrow-based, small-sized bladder PEComa, resection of the tumor by ERBT was a safe and feasible approach in our patient and may be considered for similar cases in the future.

Hepatic perivascular epithelioid cell tumor (PEComa): contrast-enhanced ultrasound (CEUS) characteristics-a case report and literature review.

Perivascular epithelioid cell tumors (PEComa) are rare mesenchymal neoplasms that arise from soft tissue of various organs such as the stomach, intestines, and lungs. We report a rare case of a primary PEComa of the liver and its characteristics on contrast-enhanced ultrasound (CEUS) in a 51-year-old female patient with an incidental finding of a hypoechoic liver lesion with peripheral hypervascularization on Doppler ultrasound. CEUS showed homogenous hypervascularity in the arterial phase that was consistent in the portal phase. In the late phase, a central washout phenomenon was evident. Histopathologic findings on sonographic biopsy of the lesion revealed a mesenchymal tumor with positivity for melanocytic markers Human Melanin Black-45 (HMB45) and Melan-A consistent with a PEComa. Despite the absence of high-risk features for malignancy, surgical resection was recommended due to the uncertain malignant potential of PEComas. The patient refused the operation and preferred sonographic follow-up; the lesion was stable over a period of 2 years. CEUS can provide valuable information regarding PEComa. After histological confirmation, the choice between resection and a watchful waiting must be made on individual basis.

Perivascular epithelioid cell tumor (PEComa) of the cystic duct.

Perivascular epithelioid cell tumors, also known as PEComas, are rare mesenchymal tumors composed mainly of epithelioid cells found in perivascular tissue. PEComas occur most frequently in the kidney, uterus, the gastrointestinal tract, liver, and retroperitoneum; those originating in the biliary tree are extremely rare. We report a case of benign PEComa of the cystic duct with positive TFE3 staining on immunohistochemistry.A 66-year-old woman was referred for a 20 mm mass adjacent to the common bile duct discovered incidentally on abdominal ultrasound. Laboratory data including tumor markers were unremarkable. The tumor appeared to arise from the cystic duct, showed early enhancement, and compressed the common bile duct on imaging studies. Endoscopic ultrasound-guided fine-needle aspiration revealed round- and spindle-shaped atypical cells with eosinophilic cytoplasm and brown deposits suggestive of melanin granules. Histological examination of the resected specimen revealed a tumor consisting of epithelioid cells forming an alveolar structure, with melanin pigmentation. Immunohistochemistry was positive for HMB-45 and TFE3, consistent with benign pigmented PEComa of the cystic duct. Melanotic, myogenic, and TFE3 staining are helpful when diagnosing PEComas arising in unusual locations.

[PEComa of the lung]. / PEComa pulmonar.

Clear cell "sugar" tumor of the lung is a rare benign tumor arising from perivascular epithelioid cells (PECs). They belong to a group of mesenchymal neoplasms called PEComas. Although widely presumed as benign, due to their rich vascular stroma they are usually avid for the different types of contrast agents used in imaging studies, mimicking a malignant lesion. We report the case of a 66-year-old man in whom a solitary pulmonary nodule was discovered during oncological staging for an adenocarcinoma of the prostate who underwent an anatomical pulmonary segmentectomy. The final pathology result was a perivascular epithelioid cell tumor (pulmonary PEComa or clear "sugar" cell tumor).

Los tumores de células claras "de azúcar" (CCTL) son lesiones benignas muy infrecuentes. Forman parte de un grupo de neoplasias mesenquimales denominadas PEComas que se originan de las células epiteloides perivasculares. Por su rico estroma vascular, suelen tener avidez por los distintos tipos de contrastes utilizados en los estudios de diagnóstico por imágenes, simulando lesiones de estirpe maligna. Presentamos el caso de un paciente de 66 años con hallazgo de un nódulo pulmonar durante la estadificación oncológica por adenocarcinoma de próstata al que se le realizó una segmentectomía pulmonar anatómica. El resultado definitivo de anatomía patológica fue tumor de células epiteloides perivasculares (PEComa pulmonar o tumor de células claras "de azúcar").

Primary retroperitoneal PEComa: an incidental finding.

Perivascular epithelioid cell neoplasm (PEComa) is a rare type of tumour, and primary retroperitoneal PEComa is rarer still. Although pulmonary lymphangioleiomyomatosis (LAM), angiomyolipomas and clear cell 'sugar' tumours of the lung are well described, relatively little is known about other members of the PEComa family. We describe a case of an asymptomatic retroperitoneal PEComa, lymphangioleiomyoma type, which appeared in a previously healthy middle-aged woman as an incidental finding, in a CT scan performed in the context of spontaneous pneumothorax. The patient underwent surgical excision of the tumour and the histopathological and immunohistochemical analysis of the surgical specimen made the definitive diagnosis. Although rare, reports of isolated retroperitoneal lymphangioleiomyoma and primary retroperitoneal PEComas NOS (not otherwise specified) are described in the literature, normally associated with pulmonary LAM. The patient's pulmonary imaging was normal. Short-term re-examination did not detect any recurrence. We also provide a literature review of this rare group of tumours.

Perivascular epithelioid cell tumour-mimicking retroperitoneal leiomyosarcoma.

A young man in his 40s was evaluated in the emergency department for abdominal and right flank pain. A CT scan of the abdomen and pelvis showed a solid, well-circumscribed lesion measuring 7.1×8.1×5.4 cm, which was arising from the retroperitoneum and extending from the third portion of the duodenum towards the right kidney. A percutaneous core biopsy was obtained, demonstrating an atypical smooth muscle neoplasm suggestive of a low-grade leiomyosarcoma. The patient underwent surgery for an en-block resection of the mass and the final pathology confirmed a perivascular epithelioid cell neoplasm without significant pleomorphism, mitosis or necrosis. Our case adds to the small number of perivascular epithelioid cell tumour cases reported in the literature and we present it in order to increase our understanding of this tumour and to assist in its appropriate diagnosis and management.

18 F-FDG and 68 Ga-FAPI-04 in the Evaluation of Aggressive Perivascular Epithelioid Cell Tumor.

ABSTRACT: A 10-year-old girl with a right renal mass underwent 18 F-FDG PET/CT and 68 Ga-FAPI-04 PET/MRI for presurgical assessment of tumor invasion and malignant potential. The mass showed low 18 F-FDG uptake and intense 68 Ga-FAPI-04 uptake. Nephrectomy was performed, and the histopathologic diagnosis was aggressive PEComa (perivascular epithelioid cell tumor). This case showed that 68 Ga-FAPI-04 PET outperformed 18 F-FDG PET in detecting aggressive PEComa.

TFE3-associated perivascular epithelioid cell tumor with complete response to mTOR inhibitor therapy: report of first case and literature review.

BACKGROUND: Perivascular epitheloid cell tumor (PEComas) are characterized by expression of both muscles, most often smooth muscle actin (in ~80% of cases) and melanocytic markers (mainly HMB-45 and Melan A). TFE 3-associated PEComas are new variant which are poorly defined due to their limited reports in literature. These tumors lack response to targeted mTOR inhibitor therapy due to lack of mutation in TSC gene. Hereby, we are reporting a case of TFE3 associated pelvic PEComa showing excellent response to Everolimus. CASE PRESENTATION: A 45-year-old female presented with complaint of abdominal mass and bleeding per vaginum for 4 months. She had a history of total abdominal hysterectomy 3 years back in view of abnormal uterine bleeding and exploratory laprotomy 7 months back to remove some pelvic mass. Imaging suggested of ill-defined heterogenous mass of 9.3 x 9.2 x 16 cm involving the uterus, cervix, and upper 1/3 vagina. Multiple omental and peritoneal deposits were also seen, making probable diagnosis of carcinoma endometrium. USG guided biopsy showed cores of fibrous tissue with the presence of cells in sheets with granular eosinophillic cytoplasm; IHC showed positivity for TFE-3, H Caldesmon, GATA-3, and Melan A- and HMB-45; and Ki 67 index was 35%. The basis of above diagnosis of PEComa was made and she was started on Everolimus; repeat imaging after 3 months of therapy showed complete response. CONCLUSION: We are reporting first case of malignant pelvic TFE 3 PEComa showing response to mTOR therapy. Identification of TFE 3 PEComa is important because they showed different biologic behavior then their conventional PEComa.

Perivascular epithelioid cell tumour (PEComa): an unusual cause of painful defaecation.

Perivascular epithelioid cell tumours (PEComa) are rare tumours of mesenchymal origin. We report a 39-year-old patient who presented with painful defecation secondary to an anorectal mass. The diagnosis of anorectal PEComa was confirmed following excision and histopathological examination. We review the literature and discuss the management of this uncommon entity.