The article describes the case of a 12-year-old boy with a history of diabetes insipidus since age 10 and diagnosed with Langerhans cell histiocytosis (LCH) with nail involvement. Multiple finger- and toenails showed varying degrees of onycholysis. Magnetic resonance imaging of the patient's head showed thickening of the pituitary stalk without mass lesions. Recognizing the clinical signs of nail LCH can lead to early and definitive diagnosis of LCH.