Colon visualization on (99m)Tc-HDP whole-body bone scan due to sigmoid colon cancer-related enterovesical fistula.

An abnormally increased uptake of the bone-seeking agent is rarely observed in structures other than the bone and urinary track on bone scintigraphy. The general etiologies of soft tissue uptake can be explained by heterotopic ossification or dystrophic and metastatic calcification. We report a case of serendipitous visualization of the entire colon on bone scintigraphy. Diffuse colonic uptake was detected on the whole-body bone scan in a patient with biopsy-proven sigmoid colon cancer. Additional imaging studies clearly showed direct bladder invasion of the sigmoid colon cancer. Imaging findings with a brief review of the literature are presented in this article.