Small intestinal carcinoma with osteoclast-like giant cells.

An elderly woman underwent jejunectomy for a large, stenosing neoplasm. Histologically, we found an undifferentiated carcinoma with scattered mononuclear and multinuclear macrophages in the intestine and lymph node metastases. The multinuclear cells, being acid phosphatase-positive and CD68-immunoreactive, are referred to as osteoclast-like giant cells. Hepatic secondaries were discovered 6 months postoperatively. The patient succumbed to a chemotherapy-related septic event. We suggest that intratumoral infiltration by mononuclear and multinuclear macrophages expresses one of the body's defense mechanisms against cancer.