An unusual pain in the hip

A 68-year-old previously healthy man presented with increasing right hip pain of 6 months duration. On examination he was found to have a hard mass in the right hip arising from the pelvic bone. Imaging studies were in keeping with a sarcoma arising from the right iliac bone. However, biopsy of this bony lesion confirmed this to be a metastatic adenocarcinoma rather than a primary bone malignancy. Further imaging and a subsequent colonoscopy revealed the primary to be a colonic adenocarcinoma. The unique and unusual nature of this case was the presentation as a solitary bony metastasis from a colonic primary. There is no previously documented report in the literature of such a rare presentation of a colonic adenocarcinoma as a solitary bony lesion mimicking a primary sarcoma in the absence of other signs or symptoms.