Unusual bone marrow metastases in a breast cancer patient.

Correspondence: Renato Alterini, M.D., Division of Hematology, University of Florence and Careggi Hospital, viale Morgagni 85, 50134 Florence, Italy. Phone: international + 39-55-4277476 • Fax: international + 39-55412098. Breast cancer is the most common malignancy in woman and it frequently metastasizes to bone.1,2 Moreover carcinoma of the breast accounts for 2–3% of cases of neoplasms with unknown primary sites.3,4 We present a case in which bone marrow biopsy led to a diagnosis of breast cancer in the absence of a clinically detected breast lesion. A 49-year-old female with a three year history of low back pain was admitted to our Institution in January 1998 because an X-ray examination had revealed the presence of multiple osteolytic lesions. Complete blood counts showed moderate anemia (Hb 10.8 g/dL), WBC 8.83109/L, platelet count 2543109/L and a slightly elevated erythrocyte sedimentation rate (ESR) (30 mm/hr). Others laboratory tests were normal. A possible diagnosis of multiple myeloma was made and the patient was submitted to bone marrow aspiration and biopsy. The bone marrow aspirate was a dry tap. The bone marrow trephine specimen was fixed in formalin, embedded in glycol methacrylate resin (JB-4 Kit, Polysciences, Inc., USA) and cut into 1.5 μm sections which were stained with Giemsa. Microscopic bone marrow examination revealed the presence of large areas of marrow replaced by well organized ductal structures which had the appearance of normal breast tissue (Figures 1 and 2). Higher magnification showed that the ducts were lined by a single cell layer and that the cells possessed apocrine snouts. A substance, probably secreted by the metastatic cells, was present within the lumen (Figure 3).