Osseous metaplasia in a recurrent symptomatic rectal lesion: a rare occurrence

Osseous metaplasia of the gastrointestinal tract is exceedingly rare. Associated with colorectal cancer, juvenile polyps , and inflammatory polyps, the exact etiology is still unknown. We present a case report on a young male with recurrent rectal polyps and rectal bleeding. Histopathology revealed an inflammatory polyp with focal osseous metaplasia.

A 30-year-old male without significant past medical history but with a significant smoking history of 10 pack-years. He initially presented to the colorectal clinic approximately 8 months prior with complaints of rectal pain and bleeding. The patient subsequently underwent colonoscopy which demonstrated a friable 2-cm mass at the dentate line. He was taken to the operating room for a transanal mass excision which, at the time, pathologic examination demonstrated a hyperplastic polyp with no evidence of dysplasia or malignancy. The patient returned to the clinic 8 months later with similar complaints of rectal bleeding. He denied any constitutional symptoms, weight loss, abdominal pain, diarrhea, or constipation. Upon rectal examination, he was noted to have a soft palpable mass blood on digital rectal exam. The patient was taken for repeat colonoscopy and was found to have a recurrent mass at the dentate line. Given the recurrent mass, the patient was taken for a re-excision in the operating room. Histopathology returned showing a 1.8 × 1.5 × 1.5 cm inflammatory polyp with focal osseous metaplasia.

Osseous metaplasia of the gastrointestinal tract is a rare occurrence that can be associated with benign polyps or malignancy. Certain markers have been shown to be linked to this process and polypectomy remains the gold standard of treatment; however, further research is warranted.