Rosai-Dorfman disease: a rare presentation of extranodal involvement of isolated bone. Case report

Introduction: Rosai-Dorfman disease (RDD), also known as sinus histiocytosis, is a rare disorder characterized by histiocyte proliferation. Case presentation: A 33-year-old man consulted the emergency department of a tertiary care institution in Cartagena de Indias, Colombia, due to a 6-month history of progressive deformity in the frontal right side of the face, associated with pain of slow progression, without any other symptoms or dermatological involvement. There were no other major findings on physical examination and laboratory tests performed were negative. Imaging scans obtained showed extensive inflammatory involvement of the frontal bone, which led to suspect osteomyelitis as the first diagnostic possibility. A biopsy of the lesion was performed with negative cultures for bacteria, which allowed establishing a diagnosis of extranodal Rosai-Dorfman disease with isolated bone involvement. Treatment with systemic corticosteroids was indicated with poor response, so methotrexate was added, achieving an evident improvement after 2 months. Conclusions: Little is known about the manifestations of Rosai-Dorfman disease and its treatment in the adult population. The present case report contributes to expanding the literature on this topic, which can present with rare symptoms that may pose challenges for its diagnosis.