Calcified Colonic Mass

A 90-year-old woman underwent evaluation for rectal bleeding. A rectal mass was detected 10 cm from the anal verge. A rectal endoscopie biopsy showed a well-differentiated adenocarcinoma. Within some of the biopsy fragments, well-formed trabecular bone was seen. The bone was microscopically normal, without atypia or architectural derangement, suggestive of sarcoma (Figure, A).

Preoperative abdominal computed tomography (Figure, B) showed a large rectal mass with diffuse rectal wall thickening, infiltration through the bowel wall, and stippling suggestive of microcalcifications. There was an enlarged perirectal lymph node. No liver lesions were seen. The patient received a course of radiotherapy to the pelvis.