Extranodal Rosai–Dorfman disease in a male involving the breast and subcutaneous soft tissue: An uncommon distribution

Rosai-Dorfman disease (RDD) is a rare, benign histiocytic disorder that typically presents with painless cervical lymphadenopathy. Breast involvement is an uncommon extranodal manifestation, and its occurrence in male patients is exceedingly rare. When it does occur, it often mimics malignancy both clinically and radiologically, necessitating biopsy for definitive diagnosis. We report the case of a 59-year-old African American male who presented with a slowly enlarging right submandibular mass. Fine-needle aspiration revealed features consistent with RDD. PET/CT showed FDG-avid masses in the right breast and left gluteal subcutaneous tissue. Given the imaging characteristics of the breast lesion, which resembled malignancy, tissue sampling was performed. These findings were consistent with multifocal extranodal RDD. Because involvement included the submandibular, breast, and gluteal sites, the team initiated systemic MEK inhibition (trametinib). Breast involvement by RDD is rare, and male cases are even scarcer in the medical literature. Lesions typically present as solid masses and are frequently classified as BI-RADS 4 or 5, prompting biopsy. Histopathology remains essential for diagnosis and to avoid overtreatment. This case highlights the importance of including RDD in the differential diagnosis of suspicious breast lesions, especially in atypical populations.