Bone marrow granulomas in infiltrating lobular breast cancer

A 50 year old woman with a history of infiltrating lobular breast carcinoma presented with back pain. Bone scan and magnetic resonance imaging were not conclusive. A bone marrow aspirate appeared normal. A routine trephine biopsy specimen showed granulomas but no obvious infiltration by carcinoma. Immunohistochemical staining with epithelial markers demonstrated carcinoma cells in the trephine specimen. This case illustrates the difficulty of detecting infiltrating lobular carcinoma in bone marrow and the value of immunological techniques in this context. It also describes the development of bone marrow granulomas as a response to infiltration by carcinoma.