Bone marrow metastases without cortical bone involvement in breast cancer patients.

Bone marrow involvement by breast carcinoma in the absence of demonstrable bone lesions is unusual. We report six patients with medullary tumor without demonstration of cortical bone abnormality on scan or radiographs. This represents 2.8% of 213 patients with breast cancer in which bone marrow examination was performed and 6.2% of those in which marrow involvement was demonstrated.