Diverse cutaneous manifestations of Erdheim-Chester disease in a woman with a history of Langerhans cell histiocytosis.

ECD: Erdheim-Chester disease LCH: Langerhans cell histiocytosis PET-CT: Positron emission tomographye computerized tomography INTRODUCTION Erdheim-Chester disease (ECD) is a rare, systemic, noneLangerhans cell histiocytosis (non-LCH). Diagnosis is based on a combination of specific radiologic, histologic, and clinical findings. Although there have been hundreds of prior reports of ECD, very few cases have described the spectrum of potential cutaneous manifestations. Most of these cases describe ECD skin findings as xanthelasmalike lesions surrounding the periorbital area, whereas 2 patients were reported to have a red-brown papular eruption affecting the chest and lower extremities. We discuss a case of a 45-year-old woman with an extensive childhood history of LCH who then presented more than 20 years later with a new eruption of polymorphous skin lesions distributed over the face, trunk, arms, and legs. These lesions were clinically varied yet histologically all consistent with xanthogranulomas. Upon further workup, the patient was found to have specific radiographic findings pathognomonic for ECD and a BRAF V600E mutation, which has been reported in both LCH and ECD. Our case is unique, in that this patient was affected by both diseases within her lifetime. Identification of the BRAF V600E mutation suggests the possibility of a common origin between LCH and ECD.