Faculty, Staff and Student Publications

Language

English

Publication Date

3-1-2024

Journal

Modern Pathology

DOI

10.1016/j.modpat.2024.100426

PMID

38219952

Abstract

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal tumors that express smooth muscle and melanocytic makers. Diagnosis of PEComas can be challenging due to focal or lost expression of traditional immunohistochemical markers, limited availability of molecular testing, and morphological overlap with much more common smooth muscle tumors. This study evaluates the use of glycoprotein nonmetastatic melanoma protein B (GPNMB) immunohistochemical staining as a surrogate marker for TSC1/2/MTOR alteration or TFE3 rearrangement to differentiate PEComas from other mesenchymal tumors. Cathepsin K was also assessed for comparison. A total of 399 tumors, including PEComas, alveolar soft part sarcomas, and other histologic PEComa mimics, were analyzed using GPNMB and cathepsin K immunohistochemistry. GPNMB expression was seen in all PEComas and alveolar soft part sarcomas with the majority showing diffuse and moderate-to-strong labeling, whereas other sarcomas were negative or showed focal labeling. When a cutoff of diffuse and at least moderate staining was used, GPNMB demonstrated 95% sensitivity and 97% specificity in distinguishing PEComas from leiomyosarcoma, well-differentiated/dedifferentiated liposarcomas, and undifferentiated pleomorphic sarcomas. Cathepsin K with a cutoff of any labeling had lower sensitivity (78%) and similar specificity (94%) to GPNMB. This study highlights GPNMB as a highly sensitive marker for PEComas and suggests its potential use as an ancillary tool within a panel of markers for accurate classification of these tumors.

Keywords

Humans, Immunohistochemistry, Cathepsin K, Melanoma, Biomarkers, Tumor, Perivascular Epithelioid Cell Neoplasms, Sarcoma, Glycoproteins, Basic Helix-Loop-Helix Leucine Zipper Transcription Factors, Membrane Glycoproteins, Receptors, Fc, GPNMB, MTOR, PEComa, TFE3, TSC1/2, perivascular epithelioid cell tumor

Published Open-Access

yes

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