Uterine perivascular epitheloid cell tumor (PEComa) with CD117 and PNL2 positivity and entrapped endometriotic glands, mimicking sex-cordlike differentiation

Systematic analysis of perivascular epithelioid cell neoplasms in the female reproductive tract: a comprehensive review

Perivascular epithelioid cell neoplasms (PEComas) are rare mesenchymal lesions, with gynecological PEComas accounting for just over a quarter of cases. Limited reports exist on gynecological PEComa, primarily treated with surgery; adjuvant therapy is considered in high-risk cases. This systematic review aims to summarize the origin and clinical, pathological and molecular characteristics of uterine PEComa, focusing on treatment options for gynecological PEComa. A comprehensive PubMed review of gynecological PEComa reports was conducted. A detailed examination of the literature ensured a thorough understanding. Gynecological PEComa diagnosis relies on histology and immunology. Despite therapy controversies, surgery remains the mainstay. Adjuvant therapy efficacy in high-risk cases is uncertain. mTOR inhibitors are the first line; alternative treatments, including angiogenesis and aromatase inhibitors, should be considered.

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.

KBA62 and PNL2: 2 new melanoma markers-immunohistochemical analysis of 1563 tumors including metastatic, desmoplastic, and mucosal melanomas and their mimics

Identification of metastatic melanoma can be difficult because of its considerable morphologic variation and mimicry of a wide variety of other tumors. The more melanoma-specific melanoma markers, MelanA/MART-1, HMB45, and tyrosinase, used in addition to S100 protein, all have limitations in sensitivity and specificity. In this study, we evaluated 2 new melanoma markers, monoclonal antibodies KBA62 and PNL2 to yet unidentified antigens, using a large panel of metastatic melanomas (n=214), desmoplastic melanomas (n=34), gastrointestinal mucosal melanomas (n=54), benign nevi (n=27), clear cell sarcomas (n=16), and nonmelanocytic tumors (n=1218). Immunoreactivity for KBA62 and PNL2 was found in all pigmented nevi and in 86% and 90% of metastatic melanomas, respectively. Mucosal melanomas showed a similar rate of PNL2 immunoreactivity but somewhat less frequent KBA62 positivity (72%). In addition, KBA62 was found to be a sensitive diagnostic marker for desmoplastic melanoma (28 of 34; 82%), whereas PNL2 was only rarely positive (2 of 34; 6%). KBA62-positive normal tissues included pericytes, vascular and parenchymal smooth muscles, and basal cells of complex epithelia, including myoepithelia, whereas PNL2 labeled only melanocytes and neutrophils. Among nonmelanocytic tumors, those that were KBA62 positive were nodular fasciitis, leiomyoma and leiomyosarcoma, gastrointestinal stromal tumors, benign and malignant nerve sheath tumors, synovial sarcoma, and subsets of various carcinomas, especially those with squamous cell/stratified epithelial differentiation. PNL2 positivity in nonmelanocytic tumors was more restricted but occurred consistently in angiomyolipoma and other perivascular epitheloid cell tumor and in chronic myeloid leukemia tissue infiltrates. KBA62 may assist in the identification of desmoplastic melanomas, but its widespread occurrence in nonmelanomas limits utility. PNL2 is highly specific for melanomas but lacks reactivity with desmoplastic melanomas. It is also an excellent supplementary marker for perivascular epitheloid cell tumor at various sites.