Nevus Psiloliparus: Newly Described Histopathological Features from Transverse Sections

The document reported on the histopathological features of nevus psiloliparus, a rare fatty tissue nevus associated with encephalocraniocutaneous lipomatosis, in an 11-year-old girl. This condition was characterized by congenital alopecia, presenting as an irregularly shaped area of hair loss on the scalp. Histopathological examination revealed a near-complete absence of mature hair follicles, with preserved arrector pili muscles and mature adipocytes in the dermis. The study suggested that the pathogenesis might be linked to mosaic mutations in the fibroblast growth factor receptor 1. The transverse sections showed "shadow" follicular units with loosely arranged collagen and a scarcity of elastic fibers.