Clinicopathological Features and Expression of Four Keratins (K10, K14, K17, and K19) in Six Cases of Eruptive Vellus Hair Cysts

The study evaluated six cases of eruptive vellus hair cysts (EVHC) focusing on histopathology and the expression of keratins K10, K14, K17, and K19. The presence of vellus hair shafts within the cystic cavity was identified as the pathological hallmark of EVHC. However, atypical changes such as multiple cysts and foreign-body granulomas were observed in three cases. The findings suggested that these atypical changes were not uncommon and indicated that EVHC likely originated from the infrainfundibulum and sebaceous duct based on keratin expression.