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.

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.

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.

Fibroma-like PEComa: a newly recognized soft tissue neoplasm in tuberous sclerosis patients-imaging features and review of literature.

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms composed of spindled to epithelioid cells that co-express both melanocytic and myogenic markers. Recently, in 2018, a distinctive variant of PEComa has been described that arises in association with tuberous sclerosis complex (TSC) and resembles a fibroma by conventional morphology (called fibroma-like PEComa). Herein, we describe a case of a fibroma-like PEComa in a 4-year-old male child with a known diagnosis of tuberous sclerosis who presented with a firm mass along the anteromedial aspect of the right knee. The mass was excised, and microscopic examination showed bland spindled to stellate cells embedded in a dense collagenous stroma, morphologically resembling a fibroma. Immunohistochemistry analysis showed positivity for desmin (a myogenic marker) and HMB45 (a melanocytic marker), a hallmark for PEComas. To our knowledge, only six cases of fibroma-like PEComa have been described in the literature so far and this is the first report of such a tumor in the medial retinaculum of the knee joint with illustrations of conventional and diffusion imaging features. This case highlights the unique association of fibroma-like PEComa lesions with TSC. This should be considered a differential diagnosis for T2 hypointense masses in tuberous sclerosis patients. In addition, a diagnosis of fibroma-like PEComa should prompt further evaluation for associated TSC.

RETROPERITONEAL PERIVASCULAR EPITHELIOID CELL NEOPLASM (PECOMA) RESPONSE TO MTOR KINASE INHIBITION. A CASE REPORT WITH LITERATURE REVIEW.

Perivascular epithelioid cell tumors (PEComas) are a very rare group of neoplasms and were first reported in 1996. These tumors represent a family of mesenchymal neoplasms, related through activation of the mammalian target of rapamycin (mTOR) inhibitor signaling pathway. The objective of this case report is to demonstrate significant regression of the tumor after neoadjuvant treatment with an oral mTOR inhibitor, following surgical removal of the mass to avoid a multiorgan resection. We present a case of a 27-year-old female with retroperitoneal PEComa and evaluated the tumor with MRI and integrated 18F-FDG-PET/CT scans at presentation and serially during treatment with everolimus. After 6 months of treatment with everolimus the tumor showed a substantial size reduction. Therefore, a multiorgan resection could be omitted. The patient has not demonstrated any disease recurrence after nearly 2 years of follow-up. PEComas are tumors with unpredictable behavior. Our report indicates that treatment of PEComas with everolimus may achieve a significant clinical response. As indicated by our case and past reports, mTOR inhibitors may be one of the best treatment options for this disease.

Fibroma-like perivascular epithelioid cell tumor: a rare case in a long bone.

Fibroma-like perivascular epithelioid cell (PEComa) tumor is an extremely rare family of mesenchymal tumors composed of cells co-expressing melanocytic and myogenic markers. To date, 13 cases of primary bone PEComa have been reported in the literature and five reported fibroma-like PEComas were found in the soft tissues of patients with tuberous sclerosis (TSC). However, no fibroma-like PEComa has been reported in bone, either sporadic or TSC-associated. Here we report the case of a 22-year-old man with known TSC, who presented for evaluation of an asymptomatic mass in his left fibula diaphysis that had been present for 5 years. He had no activity-related pain, numbness, weakness, or limitations in range of motion. Both 3-T MRI and CT demonstrated a tumor originating from the midshaft middiaphyseal fibula. Axial T1-weighted and fat-saturated T2-weighted fast spin echo images showed a well-defined lesion in the fibula with extension into the surrounding soft tissues. Whole body bone scan was negative for metastasis using technetium-99m. Renal ultrasound was unremarkable with no evidence of angiomyolipoma. Histopathology demonstrated isolated spindle cells in a dense collagenous matrix. By immunohistochemical staining, tumor cells were positive for HMB-45 and MiTF and partially positive for alpha-smooth muscle actin supporting a diagnosis of fibroma-like PEComa of the midshaft fibula. Although fibroma-like PEComa of bone is very rare, a bone tumor in the setting of TSC should raise suspicion for the diagnosis, in particular if histology demonstrates rare epithelioid cells in a densely fibrotic stroma.

Uterine PEComa initially misdiagnosed as a leiomyoma: Sonographic findings and review of the literature.

Perivascular epithelioid cell neoplasms (PEComas) are rare mesenchymal tumors with malignant potential that arise from gynecological organs in up to 25% of cases. The lack of data regarding the preoperative US features of uterine PEComas is reflected by the frequent misdiagnosis with leiomyomas. We describe the sonographic appearance of a richly vascularized cervical PEComa mimicking a myoma and report the analysis of six additional cases in the literature with a description of their ultrasound features. Most cases involved a single lesion arising from the uterine cervix with a rapid growth pattern, regular margins, heterogeneous echogenicity, absence of shadowing, and moderate-to-rich vascularity.

Abdominal perivascular epithelioid cell tumor (PEComa) without visible fat: a clinicopathologic and radiological analysis of 16 cases.

OBJECTIVE: To retrospectively review the clinicopathological features and computed tomography (CT) and magnetic resonance imaging (MRI) findings of abdominal perivascular epithelioid cell tumor without visible fat (PEComawvf). MATERIALS AND METHODS: Sixteen patients with surgically and pathologically confirmed perivascular epithelioid cell tumor without visible fat were enrolled. Their clinicopathological data and imaging findings were retrospectively reviewed. The CT and MRI features, including location, size, shape, margin, density, calcification, cystic necrosis and enhancement pattern, were analyzed. RESULTS: There were 4 males and 12 females (median age, 46 years; range, 21-65 years) in this study. All 16 patients were diagnostic asymptomatic unenhanced CT or MRI and revealed a well-defined (n = 13), oval (n = 10), mass with heterogeneous (n = 6) or homogeneous density/signal intensity (n = 7), calcification and hemorrhage was no found in any cases. On enhanced CT/MRI, markedly enhancement patterns (n = 14) were observed. The "peripheral enhancement" sign was observed in 13 cases. One in 16 cases recurrence was discovered during the follow-up period. CONCLUSIONS: Dynamic CT, MRI and pathology of PEComawvf had some characteristics of non-aggressive pattern of performance, and MRI would provide beneficial detection of microscopic fat. Enhanced imaging showed PEComawvf is characterized by a "peripheral enhancement" with a marked enhancement pattern. Knowing these characteristics could contribute to improving the understanding abdominal PEComawvf and related palliative care.

[Intraocular perivascular epithelioid cell tumor: report of two cases].

Two male patients presented with painless vision loss to blindness in one eye, and the radiography examinations revealed an intraocular mass suspicious for choroidal melanoma. They underwent enucleation. The histopathological and immunohistochemical findings were compatible with the diagnosis of intraocular perivascular epithelioid cell tumor. Because of its rarity, intraocular perivascular epithelioid cell tumor is easy to be confused with other intraocular tumors on histopathological and immunohistochemical examinations. (Chin J Ophthalmol, 2021, 57: 857-860).

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

BACKGROUND: Perivascular Epithelioid Cell Tumors (PEComa) is an extraordinarily rare mesenchymal neoplasm especially the malignant type originating from the lung. To date, only 8 cases of malignant or malignant potential pulmonary PEComa had been documented. Firm diagnostic criteria for malignant pulmonary PEComa need urgently to be established. CASE PRESENTATION: We report a challenging case of malignant pulmonary PEComa combined with a primary adenocarcinoma in a 54-year-old man. The PEComa-like tumor showed strong Melan-A and weak transcription factor E3 (TFE3) protein expression but no TFE3 gene rearrangement. The carcinoma-like nodule was recognized as a poorly differentiated primary lung adenocarcinoma. DISCUSSION AND CONCLUSIONS: Our case report was the first case of malignant pulmonary PEComa synchronous with a primary adenocarcinoma and studied the dilemma of diagnosing benign versus malignant criteria for this uncommon tumor.

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

BACKGROUND: Perivascular epithelioid cell tumor, an extremely rare mesenchymal tumor, could be ubiquitous but rarely arises from pancreas. Surgery is considered the most appropriate treatment. Nevertheless, activation of mTOR pathway seems to be a common pathogenic event in PEComas paving the way to chemotherapy by mTOR inhibitor. METHOD: A 17 year-old man presented a hypervascular tumor of 55 mm, located in the head of pancreas without bile duct or pancreatic duct compression. RESULTS: Histopathology showed epithelioid cells with clear or focally granular eosinophilic cytoplasm with melanocytic (HMB-45, Melan-A) and myoid markers which confirmed diagnosis of PEComa. Given the absence of worrisome feature, we ruled out surgery and decided to initiate treatment with Sirolimus, an mTOR inhibitor. After 3.5 years, we showed a significant reduction in size of the tumor. CONCLUSION: This first case of pancreatic PEComa treated by mTOR inhibitor without surgery suggests a good efficiency of this therapy.

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

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

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

INTRODUCTION: Perivascular epithelioid cell tumor (PEComa) is a family of rare mesenchymal tumors composed of histologically and immunohistochemically distinctive perivascular epithelioid cells (PECs). These tumors have been described at multiple anatomic sites. PEComas presenting in bone are especially rare and they have been reported to be either primary or metastatic lesions. None of them is located at the level of the foot. PATIENT: We report on a case of primary bone PEComa of the talus, the first one to be published to the best of our knowledge. Treatment and result: Limb sparing surgical treatment has been done using intralesional tumor removal, burring and application of argon beam at the tumor walls and primary filling of the tumor cavity by bone cement with so far absence of any tumor recurrence documented by multiple histological sections at second look operation nine months after primary surgery, where cement has been replaced by autologous bone graft, and by subsequent follow-up. CONCLUSIONS: PEComa is a very rare tumor, and its presence in bone is especially rare. The here reported case of PEComa presenting at the level of the talus is, to the best of our knowledge, the first case to be reported in the literature.

Benign clear cell "sugar" tumor of the lung in a patient with Birt-Hogg-Dubé syndrome: a case report.

BACKGROUND: Birt-Hogg-Dubé (BHD) syndrome is a rare inherited autosomal genodermatosis and caused by germline mutation of the folliculin (FLCN) gene, a tumor suppressor gene of which protein product is involved in mechanistic target of rapamycin (mTOR) signaling pathway regulating cell growth and metabolism. Clinical manifestations in BHD syndrome is characterized by fibrofolliculomas of the skin, pulmonary cysts with or without spontaneous pneumothorax, and renal neoplasms. There has been no pulmonary neoplasm reported in BHD syndrome, although the condition is due to deleterious sequence variants in a tumor suppressor gene. Here we report, for the first time to our knowledge, a patient with BHD syndrome who was complicated with a clear cell "sugar" tumor (CCST) of the lung, a benign tumor belonging to perivascular epithelioid cell tumors (PEComas) with frequent causative relation to tuberous sclerosis complex 1 (TSC1) or 2 (TSC2) gene. CASE PRESENTATION: In a 38-year-old Asian woman, two well-circumscribed nodules in the left lung and multiple thin-walled, irregularly shaped cysts on the basal and medial area of the lungs were disclosed by chest roentgenogram and computer-assisted tomography (CT) during a preoperative survey for a bilateral faucial tonsillectomy. Analysis of the resected tumor showed large polygonal cells with clear cytoplasm proliferating in a solid pattern. Immunohistochemistry revealed that these tumor cells were positive for microphthalmia-transcription factor, S100, and CD1a but negative for HMB45, indicating that the tumor was a CCST. Genetic testing indicated that the patient had a germline mutation on exon 12 of the FLCN gene, i.e., insertion of 7 nucleotides (CCACCCT) (c.1347_1353dupCCACCCT). Direct sequencing of the FLCN exon 12 using genomic DNA obtained from her microdissected CCST cells clearly revealed loss of the wild-type FLCN sequence, which confirmed complete functional loss of the FLCN gene. On the other hand, no loss of heterozygosity around TCS1- or TSC2-associated genetic region was demonstrated. CONCLUSION: To our knowledge, this is the first report of CCST of the lung in a patient with BHDS, indicating that CCST should be added to the spectrum of pulmonary manifestations of BHDS.

Perivascular epithelioid cell tumor of the descending colon mimicking a gastrointestinal stromal tumor: a case report.

BACKGROUND: We present a case of perivascular epithelioid cell tumor (PEComa), which clinically and histologically mimics a gastrointestinal stromal tumor (GIST). CASE PRESENTATION: A 42-year-old woman was found to have a mass in the left flank during her annual medical checkup. Computed tomography examination revealed a submucosal tumor of the descending colon. Surgeons and radiologists suspected that the lesion was a GIST, and left hemicolectomy was performed without biopsy. Microscopic examination showed that the lesion was composed of spindle and epithelioid cells, which were immunohistochemically negative for c-kit and positive for platelet-derived growth factor receptor (PDGFR) α. Initial diagnosis of PDGFRα-positive GIST was made. However, gene analysis did not reveal mutations in PDGFRα. Additional immunohistochemistry showed that tumor cells were positive for human melanin black 45 (HMB45), melanA, and the myogenic marker calponin. A final diagnosis of PEComa was made. CONCLUSION: PEComa should be included in the differential diagnosis of PDGFRα-positive spindle cell tumors in the wall of the gastrointestinal tract.