Breast Cancer Mimic: Cutaneous B-Cell Lymphoma Presenting as an Isolated Breast Mass

BACKGROUND Primary cutaneous B-cell lymphoma typically localizes to the skin, and dissemination to internal organs is rare. Lymphomatous involvement of the breasts is also rare. We describe the clinical and radiological findings of an unusual case of primary cutaneous B-cell lymphoma presenting as an isolated breast mass without associated skin changes. CASE PRESENTATION The patient was a 55-year-old Caucasian female who initially presented with cutaneous B-cell lymphoma around her eyes and forehead with recurrence involving the skin between her breasts. Three years after terminating treatment due to a lack of symptoms, she presented for an annual screening mammogram that found a new mass in her upper inner right breast without imaging signs of cutaneous extension. On physical examination, there were no corresponding skin findings. Due to the suspicious imaging features of the mass that caused concern for primary breast malignancy, she underwent a core biopsy which revealed cutaneous B-cell lymphoma. CONCLUSION When evaluating patients with a systemic disease who present with findings atypical for that process, it is important to still consider the systemic disease as a potential etiology, particularly with lymphoma given its reputation as a great mimicker.