Adult multisystem Langerhans cell histiocytosis with cutaneous involvement manifesting as extensive flexural erosions.

Langerhans cell histiocytosis is a great imitator of other diseases with an often-delayed diagnosis leading to a concerning delay in commencing treatment. We present the case of a male who was previously diagnosed with Hailey-Hailey disease, in whom several treatment options had failed, was referred to the dermatology team for evaluation of a 3-month atypical, extensive, painful and pruritic cutaneous flexural eruption. On systems review, he reported a 2-year history of polyuria and polydipsia.