Cutaneous Rosai-Dorfman Disease Misdiagnosed as Granulomatous Dermatitis: A Diagnostic Pitfall

Cutaneous Rosai-Dorfman disease (CRDD) is an uncommon non-Langerhans cell histiocytosis that may occur without systemic involvement and lacks specific clinical features. We report a 17-year-old female with a slowly enlarging chest lesion initially diagnosed as granulomatous dermatitis on a 4-mm punch biopsy. The lesion was treated as an inflammatory process without improvement. Complete excision revealed a multinodular dermal and subcutaneous infiltrate of large histiocytes demonstrating emperipolesis, confirming CRDD. Systemic evaluation was negative. The initial limited biopsy did not capture defining features, delaying diagnosis. Persistent nodular lesions that fail to respond to therapy should prompt reconsideration and more representative tissue sampling. We have also tabulated selected reported cases, which further demonstrate that CRDD is frequently misdiagnosed in routine clinical practice due to nonspecific morphology and limited biopsy sampling.