Erdheim–Chester disease: expanding the spectrum of cutaneous manifestations

Background: Erdheim–Chester disease (ECD) is a rare condition and there is limited information available regarding its cutaneous manifestations. Objectives: To describe the clinical and histopathological features of cutaneous involvement in ECD. Methods: This study is a single-centre retrospective analysis of patients 18 years old and older with biopsy-proven diagnosis of ECD between 1 January 1990 and 1 April 2017. Patients from this cohort were screened for cutaneous manifestations, and BRAF c.1799T>A (p.V600E) mutational analysis was conducted in novel skin manifestations. Primary outcomes included cutaneous manifestations (morphology and topography of lesions) and BRAF mutation status in novel cutaneous findings. Results: Of 71 patients with ECD, 15 patients (21%; median age 52 years) presented with cutaneous manifestations. The most common finding was the presence of xanthelasma-like lesions (n = 8). Two patients had nonfacial cutaneous xanthomas. Seven patients presented with nonxanthomatous cutaneous involvement, with the most common finding being subcutaneous nodules (n = 5). A single patient presented with granuloma annulare-like lesions. Another patient with mixed ECD and Langerhans cell histiocytosis presented with lightly scaling, pink-red macules. In three patients, the appearance of skin lesions was the first manifestation of the disease. Most patients presented with bone/extremity pain, weight loss and other constitutional symptoms at the time of diagnosis. The BRAF V600E mutation was not found in patients with panniculitis-like and granuloma annulare-like lesions. Conclusions: The most common presentation in ECD is the presence of periorbital xanthelasma-like lesions. Other presentations include nonfacial cutaneous xanthomas, panniculitis-like lesions and granuloma annulare-like lesions. Associated symptoms at presentation include bone/extremity pain and weight loss. What's already known about this topic?. Erdheim–Chester disease is a rare form of non-Langerhans cell histiocytosis characterized by lipid-laden macrophage infiltration of tissue and subsequent fibrosis. Cutaneous involvement is found in approximately 25% of patients, with the majority presenting with periorbital xanthelasma-like lesions. What does this study add?. We report two novel cutaneous findings: panniculitis-like lesions and granuloma annulare-like lesions. Associated bone/extremity pain and weight loss should raise suspicion for Erdheim–Chester disease.