Cutaneous manifestations of Erdheim-Chester disease (ECD): Clinical, pathological, and molecular features in a monocentric series of 40 patients

Background: Erdheim-Chester disease (ECD) is a rare form of non-Langerhans cell histiocytosis with possible cutaneous-specific involvement. Objectives: We sought to describe the clinical, pathological, and molecular features of the cutaneous manifestations of 40 patients with ECD identified from a cohort of 123 patients. Methods: Confirmed cases of patients with ECD were included in a single-center retrospective observational study. Clinical and pathological cutaneous features were analyzed and BRAF(V600E) mutation was determined. Results: The most frequent ECD cutaneous manifestations were xanthelasma-like lesions (XLL), which occurred in 31 (25%) patients. Other ECD cutaneous lesions were patches or papulonodular lesions. Mixed form of ECD and cutaneous Langerhans cell histiocytosis presented with crusty papules of the folds in some patients. Compared with classic xanthelasma palpebrarum, ECD XLL pathology more frequently involved the reticular dermis, displayed more multinucleated or Touton cells, and showed less extensive fibrosis. BRAF(V600E) mutation was more frequently detected in patients with cutaneous involvement than in those without (76% vs 52%; P = .005) and constantly found in 10 XLL. Limitations: Some clinical data were not available because of the retrospective design of the study. Conclusions: XLL are the most frequent cutaneous ECD manifestations and might be targeted both for pathology and determination of BRAF mutational status.