The pericyte antigen RGS5 in perivascular soft tissue tumors

Abstract

Summary Perivascular soft tissue tumors are relatively uncommon neoplasms of unclear lineage of differentiation, although most are presumed to originate from or differentiate to pericytes or a modified perivascular cell. Among these, glomus tumor, myopericytoma, and angioleiomyoma share a spectrum of histologic findings and a perivascular growth pattern. In contrast, solitary fibrous tumor was once hypothesized to have pericytic differentiation—although little bona fide evidence of pericytic differentiation exists. Likewise the perivascular epithelioid cell tumor (PEComa) family shares a perivascular growth pattern, but with distinctive dual myoid-melanocytic differentiation. RGS5, regulator of G-protein signaling 5, is a novel pericyte antigen with increasing use in animal models. Here, we describe the immunohistochemical expression patterns of RGS5 across perivascular soft tissue tumors, including glomus tumor (n = 6), malignant glomus tumor (n = 4), myopericytoma (n = 3), angioleiomyoma (n = 9), myofibroma (n = 4), solitary fibrous tumor (n = 10), and PEComa (n = 19). Immunohistochemical staining and semi-quantification was performed, and compared to αSMA (smooth muscle actin) expression. Results showed that glomus tumor (including malignant glomus tumor), myopericytoma, and angioleiomyoma shared a similar diffuse immunoreactivity for RGS5 and αSMA across all tumors examined. In contrast, myofibroma, solitary fibrous tumor and PEComa showed predominantly focal to absent RGS5 immunoreactivity. These findings further support a common pericytic lineage of differentiation in glomus tumors, myopericytoma and angioleiomyoma. The pericyte marker RGS5 may be of future clinical utility for the evaluation of pericytic differentiation in soft tissue tumors.

Myopericytoma/myopericytomatosis of the lower extremity in two young patients: a recently designated rare soft tissue neoplasm

“…As mentioned above, the spectrum of perivascular tumors, which includes myopericytoma, shares a specific immunohistochemical profile including expression of alpha smooth muscle actin (αSMA), muscle-specific actin, h-caldesmon, CD146, platelet-derived growth factor receptor beta-subunit (PDGFRβ), and regulator of G-protein signaling 5 [18] , [19] . Recently, Shrestha et al.…”

Regulator of G protein signaling 5 restricts neutrophil chemotaxis and trafficking

“…Adherent neutrophils can traverse the activated endothelium through both transcellular and paracellular routes, both of which require active participation of blood vessel cells through G␣ i signaling (50,51). RGS5 is also expressed in pericytes, contractile smooth muscle-like cells that encircle microvascular ECs (52). Neutro-phil crawling and transmigration both depend on pericyte function (53).…”

Ang-2 but not Ang-1 expression in perivascular soft tissue tumors

“…_ 2 ) T D $ F I G ] of aSMA, CD146, PDGFRb, and RGS5. 4,5 These markers are quite similar to antigens normally expressed in non-neoplastic pericytes. Perivascular epithelioid cell tumors (PEComa) to some extent share this staining profile.…”

“…Recently, we reported a shared pericyte immunophenotype among glomus tumor, myopericytoma, and angioleiomyoma, including diffuse immunoreactivity for aSMA, CD146, PDGFRb, and RGS5. 4,5 However, these known pericyte antigens have relatively diverse expression profiles, both in normal and neoplastic tissues (see 6,7 for a review).…”