Extranodal Rosai-Dorfman Disease of the Breast Presenting as Inflammatory Breast Cancer: A Rare Diagnostic Challenge

A 50-year-old woman presented with a left breast (LB) mass that had progressed over 10 months.Her history included a 5 pack-year smoking history.Menarche occurred at age 13, and she delivered her only child by cesarean section at age 27; she did not breastfeed.There was no personal or family history of malignancy.On examination, a poorly defined, indurated mass measuring approximately 4 cm in greatest diameter was palpated in the upper outer quadrant (UOQ) of the LB.The overlying skin showed inflammatory changes (peau d'orange), and the breast was enlarged compared with the right side (Figure 1a).A firm, mobile, ipsilateral axillary lymph node measuring 1 cm was also detected.Ultrasonography demonstrated a hypoechoic UOQ mass with edema, fluid collections, and associated inflammatory features, measuring up to 3 cm.Mammography showed a poorly defined, hyperdense lesion in the same region (Figures 1b,c).The Breast Imaging Reporting and Data System (BI-RADS) score was 1 for the right breast and 3 for the LB.An ultrasound-guided core needle biopsy revealed non-specific inflammatory changes.Because of radioclinical discordance between the imaging and clinical findings, surgical excision of the mass was performed without lymph node sampling.