Abdominal bone formation.

A 34-year-old man with a history of severe peritonitis was referred to the hospital for reconstruction of intestinal continuity. Preoperative CT scan revealed extensive heterotopic mesenteric ossification (HMO). Intestinal continuity was then reconstructed after complete removal of the enormous dendritic intraabdominal bone formation. The exact etiology of HMO remains unknown. It is hypothesized to result from the dislocation of small osseous fragments from the xiphoid or os pubis as well as from osteogenic differentiation of local mesenchymal progenitor cells.