Segmental absence of small intestinal musculature.

Three instances of segmental absence of small intestinal musculature are described. Based on their clinical and pathological features and on the 12 cases previously described in the English literature, these can be classified into two groups: primary and secondary. In the primary group, the etiology is unknown, the onset of symptoms is acute, and there are no pathologic findings in the remaining layers of the small bowel except for superimposed perforation, or intussusception. In the secondary group, there is a longer history of intestinal symptoms and of multiple surgical procedures. Histologically, there may be ischemic necrosis of remaining layers, fibrosis, calcification, chronic inflammation, and presence of macrophages. These findings indicate secondary destruction of muscle layers due to ischemia and/or infarction, interruption of the blood supply, or trauma.