Heterotopic ossification in skeletal muscle metastasis from colonic adenocarcinoma--a case report.

Colonic adenocarcinoma metastasising to the skeletal muscle is rare. A-56-yr-old Malay man was diagnosed to have adenocarcinoma of the right colon [Dukes B] for which a right hemicolectomy was performed, followed by radiotherapy and chemotherapy. Five years later the patient presented with a mass in the rectus abdominis muscle. The serum carcinoembryonic antigen was 71 ng/Ml. The mass was resected. Gross and microscopical examination showed multiple deposits of mucin-secreting adenocarcinoma with prominent heterotopic ossification in the stroma. The exact pathogenesis and significance of heterotopic ossification is not clear, but bone morphogenetic proteins may play an important role.