A rare case of asynchronous bilateral B-cell lymphoma of the breast.

We report an asynchronous bilateral malignant lymphoma of the breast, in a 56-year-old woman, presenting unusual clinical signs and histological features. The patient, who had a family history of breast cancer, had undergone a standard right radical mastectomy four years previously for a non-epithelial malignant tumor. At that time, the tumor was thought to be a stromal sarcoma, because some of the neoplastic cells were elongated or vacuolated. The patient recently became aware of a rapidly growing tumor of the left nipple without erosion or pain. This tumor underwent biopsy, and the histological examination showed a non-Hodgkin's lymphoma of diffuse mixed type. Staging procedures demonstrated no sign of generalized disease. Following a modified left radical mastectomy for optimal local control and accurate staging, adjuvant chemotherapy consisting of vincristine, cyclophosphamide, prednisolone and doxorubicin was initiated. Immunohistochemical staining for PAN-B and leucocyte common antigen revealed both tumors to be malignant lymphomas of B-cell type, and the first lymphoma of the right breast was thought to be showing 'signet ring' cell change. Since the two tumors were morphologically quite different from each other, it was suggested that they were asynchronous bilateral primary malignant lymphomas; however, the possibility remains that the recent left breast tumor is a recurrence of the malignant lymphoma of the right breast. The patient is currently disease-free, 10 months after surgery.