Computed tomography of isolated osteoblastic colon metastases in the bony pelvis.

Skeletal metastases from colorectal carcinoma are unusual and osteoblastic metastases are quite rare. Three cases are described in which an isolated recurrence of a previous colorectal carcinoma occurred within the pelvic bones, without evidence of skeletal metastases elsewhere so that local spread via portocaval anastomoses in the pelvis is postulated. In all three cases, proliferative calcification and new bone formation occurred within an expansile, destructive lesion, suggesting the occurrence of a synergistic effect between the underlying bone and a malignant neoplasm which has a propensity to calcify.