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

BACKGROUND

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.

METHODS

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).

RESULTS

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.

CONCLUSIONS

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.