Toxic megacolon in ulcerative colitis complicated by pneumomediastinum: report of two cases.

We describe two cases of universal ulcerative colitis in which toxic megacolon was complicated by the unusual occurrence of air tracking retroperitoneally through the diaphragm and the mediastinum, without signs of free intraperitoneal air, and ultimately presenting as subcutaneous emphysema in the neck. Physicians should remain alert to this unusual presentation of air leakage from the colon in toxic ulcerative colitis, in order to appreciate the potential gravity of the situation.