A congenital abnormality in the arrangement of muscle bundles in a segment of the distal ileum, producing obstruction: a variant of the so-called "giant Meckel's diverticulum".

This 4-year-old male child was diagnosed at birth as having several minor congenital anomalies. X-rays taken during the first year of his life showed a single, massively dilated loop of bowel in the upper abdomen, not appreciated at the time. In 1980 he was admitted to Jackson Memorial Hospital with the diagnosis of small bowel obstruction. An upper gastrointestinal series showed one tremendously dilated loop of distal ileum. At laparotomy, the patient was found to have extreme segmental dilatation of one loop of distal ileum which ended abruptly; there was no evident external cause for obstruction. The resected loop contained in excess of 200 cc of watery brown liquid. The mucosal folds and underlying smooth muscle bundles, in the dilated portion only, were not arranged circumferentially but rather in a distinctive finger-print-like pattern with trifurcations, whorls, and intricate interdigitations which had probably produced contractions of a circus type rather than normal peristaltic waves. We have been able to find only three reports in the literature in which, as was the case here, the so-called "giant Meckel's diverticulum" presented as a single tremendously dilated segment of ileum, sharply demarcated at its distal end. In none of them is there any description of the orientation of muscle bundles. We believe that the abnormal arrangement of smooth muscle in the muscular coat in this specimen, and perhaps in the others, probably represents the underlying cause for the extreme localized dilatation.