Cutaneous Rosai–Dorfman disease involving the left ear responsive to systemic glucocorticoid: a case report

A 49-year-old man presented with a 1-year history of red facial nodules and a 3-month history of left-sided hearing decline. A biopsy revealed mixed inflammation and emperipolesis of histiocyte-like cells. An immunohistochemical analysis demonstrated that the histiocyte-like cells were positive for S100 and CD68 PGM1 and negative for CD1a and CD207, confirming the diagnosis of cutaneous Rosai–Dorfman disease (CRDD). The initial treatment consisted of oral prednisone acetate combined with methotrexate. Due to limited efficacy and adverse effects, methotrexate was discontinued, and prednisone acetate monotherapy was used. After 2 months, the patient’s skin lesions gradually resolved, and hearing improved. This case demonstrates that CRDD involving the ear can lead to hearing recovery following systemic corticosteroid therapy.