Ossification of a rectal tumor: an uncommon finding

The authors report the case of a 29-year-old woman with partially calcified stage cT4N2M0 mucoid adenocarcinoma of the mid-rectum. Concomitant neoadjuvant chemoradiotherapy was administered. Preoperative CT scan and MRI demonstrated stable disease with a marked increase of its mineralized component. Histology confirmed a mucoid adenocarcinoma with ossified matrix. Osteocytes were identified in the tumor. TNM (5th edition) staging was ypT3N2M1. This case illustrates heterotopic ossification of a rectal tumor, a fairly uncommon finding. The mechanism of heterotopic bone formation within gastrointestinal adenocarcinoma has not been fully elucidated. The impact of this particular feature on patient outcome is unknown.