Purpuric nail striae as the initial manifestation in multisystem Langerhans cell histiocytosis.

Nail involvement in Langerhans cell histiocytosis (LCH) is very uncommon. We describe a 9-month-old boy with longitudinal purpuric bands, onychodystrophy, and paronychias on his fingernails and toenails, which antedated manifestations of recurrent bilateral spontaneous pneumothorax and elevated transaminases. The diagnosis of nail LCH was then confirmed by immunohistochemistry demonstrating positive S100 and CD1a staining in the epithelium of nail bed tissue. This case report affirms that nail involvement may be the initial manifestation of multisystem LCH and could portend an unfavorable prognosis.