15120 Erdheim-Chester disease: Case report with multisystem manifestations

Abstract

A 61-year-old man presented with a 3-year history of extensive yellow plaques on both eyelids. The patient also reported retro-orbital headache, lower limb pain, polydipsia-polyuria and progressive fatigue, since last year. Reflectance confocal microscopy showed clusters of multinucleated roundish structures, along with discoid-shaped structures, at superficial dermis. Histopathology examination proved them to be Touton cells and foamy histiocytes respectively. Immunohistochemically, foamy histiocytes were positive for CD68 and negative for S-100 and CD1a. Further investigation revealed retro-orbital masses, osteosclerosis of the distal long bones, pleural and pericardial effusion, diabetes insipidus and retroperitoneal fibrosis. Therefore, the patient was diagnosed with Erdheim-Chester disease. A BRAF V600E mutation was confirmed and vemurafenib (1920 mg/day) was initiated. However, three weeks later the patient developed DRESS syndrome and the treatment was stopped. After multidisciplinary discussion, it was decided to begin treatment with cobimetinib (40 mg/day). A clinically and radiographically (assessed with 18F-FDG PET) significant improvement was noted after three months of therapy. Erdheim-Chester disease is a non-Langerhans cell histiocytosis with possible cutaneous involvement. Diagnosis is challenging and should be suspected in the presence of xanthelasma-like lesions and signs of a multisystem disease. Since 2012 with discovery of BRAF mutations in about 50% of patients, BRAF inhibitors have become a first-line treatment. More recently, cobimetinib, a MEK inhibitor, has been used in patients with BRAF wild-type disease, or in who cannot tolerate or do not respond to vemurafenib. To the best of our knowledge, we report herein the first case of Erdheim-Chester disease evaluated by confocal microscopy.