PEComa of the Adrenal Gland

Abstract

PEComas are a family of mesenchymal neoplasms composed of histologically distinctive perivascular epithelioid cells which demonstrate myomelanocytic differentiation. PEComas of the adrenal gland are very rare and can represent a considerable diagnostic challenge given their morphologic overlap with more common adrenal cortical neoplasms. We present the clinicopathologic features of 7 primary adrenal PEComas. The cohort comprised 5 male and 2 female patients with a median age of 63 years (range: 31 to 71 y). One patient had Birt-Hogg-Dubé syndrome and another had Lynch syndrome; however, none had a history of tuberous sclerosis complex. Histologically, tumors showed nested and/or sheet-like growth and epithelioid cytomorphology with pale-to-eosinophilic granular cytoplasm. Two tumors had an admixed spindle cell component. There was a median of 4 mitoses per 10 HPFs (range: 0 to 8). Necrosis was present in 4 tumors and lymphovascular invasion in 1. Four tumors were classified as malignant. By immunohistochemistry, tumors were positive for HMB-45 (3/7), MITF (3/3), Melan-A (3/7), smooth muscle actin (5/7), desmin (5/7), and caldesmon (1/1). Two tumors were positive for TFE3 (2/4). Inhibin and SF1 were negative in all tumors assessed (0/6). Of 3 patients with available clinical follow-up information, 1 patient developed locally recurrent and metastatic disease (at 18 mo) and was alive with persistent disease at the last follow-up. Two patients had no recurrent or metastatic disease at the last follow-up (60 and 25 mo). Although PEComas of the adrenal gland are rare, pathologists need to be alert to this entity in the differential diagnosis of primary adrenocortical neoplasms. In suspected cases, the judicious use of melanocytic and smooth muscle markers, in addition to TFE3 and markers of adrenocortical differentiation (such as SF1 and inhibin) can assist in diagnosis. As in PEComas arising at other visceral sites, an association with tuberous sclerosis complex seems to be uncommon.

18F-FAPI for Imaging Metastatic Perivascular Epithelioid Cell Neoplasm

“…Perivascular epithelioid cell tumors (PEComas) are a family of mesenchymal neoplasms, originating from the perivascular epithelioid cell line (PEC), and usually exhibiting distinctive histological, immunological, and genetic characteristics of melanocytic and smooth muscle markers. 1,2 Recent studies showed positive 18 F-FDG uptake in malignant PEComas and their metastatic foci and negative uptake in benign PEComas. [3][4][5][6][7] In the present case, only the primary lesion of this PEComa with diffuse metastases did exhibit elevated glucose consumption.…”

“…Other than showed intense uptake in the aforementioned FDG-avid lesions (SUV max of 19.1, see arrow in B), axial fused PET/CT images of 18 F-FAPI PET/CT revealed diffuse nodular hypermetabolic foci in the right submandibular gland (SUV max of 18.4, see arrow in C), bilateral thyroid gland (SUV max of 15.1, see arrow in D), anterosuperior mediastinum (SUV max of 25.2, see arrow in E), and multiple muscle tissue and/or subcutaneous fats (SUV max of 8.3, see arrow in F and G). Subsequently, the patient underwent CT-guided biopsy of the left abdominal wall lesion; immunohistochemical examination showed positive staining for HMB45, MelanA, SMA, and Ki-67 (<3%), which confirmed the diagnosis of perivascular epithelioid cell neoplasm.Perivascular epithelioid cell tumors (PEComas) are a family of mesenchymal neoplasms, originating from the perivascular epithelioid cell line (PEC), and usually exhibiting distinctive histological, immunological, and genetic characteristics of melanocytic and smooth muscle markers 1,2. Recent studies showed positive 18 F-FDG uptake in malignant PEComas and their metastatic foci and negative uptake in benign PEComas [3][4][5][6][7].…”