Elastophagocytosis and interstitial granulomatous infiltrate are more common in extragenital vs genital lichen sclerosus.

Abstract

Genital and extragenital lichen sclerosus (LS) share similar histopathologic features. A recent small series documented elastophagocytosis uniquely in extragenital LS. We evaluated a larger series of LS for elastophagocytosis, elastic fiber loss, and other histopathologic features. We evaluated matrix metalloproteinase (MMP) expression to determine if these proteins play an etiologic role. Genital (n = 42) and extragenital (n = 41) LS biopsies were examined for histopathologic features, elastic fiber alteration (Verhoeff van Gieson staining), and MMP-2 and MMP-9 expression (immunohistochemistry). Elastophagocytosis and an interstitial granulomatous pattern were significantly more common in extragenital LS than genital LS (43.9% vs 4.7% and 56.1% vs 9.5%). Extragenital LS had mild/focal elastic fiber loss (43.9%), while genital LS had moderate (61.9%) or marked (19%) loss. MMP-9 was diffusely expressed in histiocytes in both types of LS (genital 97.5%; extragenital 100%). Weak MMP-2 expression was seen in genital (58%) and extragenital (55%) LS. Extragenital LS, but not genital LS, frequently exhibits elastophagocytosis and interstitial granulomatous infiltrate, and these patterns could contribute to elastic fiber destruction in extragenital LS. While MMP-2 and MMP-9 expression are common in LS, expression did not significantly differ depending on anatomic site and thus is unlikely to explain observed histopathologic differences.