Pericyte antigens in angiomyolipoma and PEComa family tumors

Perivascular epithelioid cell tumors (PEComas) are an uncommon family of soft tissue tumors with dual myoid-melanocytic differentiation. Although PEComa family tumors commonly demonstrate a perivascular growth pattern, pericyte antigen expression has not yet been examined among this unique tumor group. Previously, we demonstrated that a subset of perivascular soft tissue tumors exhibit a striking pericytic immunophenotype, with diffuse expression of αSMA, CD146, and PDGFRβ. Here, we describe the presence of pericyte antigens across a diverse group of PEComa family tumors (n = 19 specimens). Results showed that pericyte antigens differed extensively by histological appearance. Typical angiomyolipoma (AML) specimens showed variable expression of pericyte antigens among both perivascular and myoid-appearing cells. In contrast, AML specimens with a predominant spindled morphology showed diffuse expression of pericyte markers, including αSMA, CD146, and PDGFRβ. AML samples with predominant epithelioid morphology showed a marked reduction in or the absence of immunoreactivity for pericyte markers. Lymphangiomyoma samples showed more variable and partial pericyte marker expression. In summary, pericyte antigen expression is variable among PEComa family tumors and largely varies by tumor morphology. Pericytic marker expression in PEComa may represent a true pericytic cell of origin, or alternatively aberrant pericyte marker adoption. Markers of pericytic differentiation may be of future diagnostic utility for the evaluation of mesenchymal tumors, or identify actionable signaling pathways for future therapeutic intervention.