Histological phenotypes of enteric smooth muscle disease causing functional intestinal obstruction in childhood

Aims : Functional intestinal obstruction or chronic idiopathic intestinal pseudo-obstruction is due to defects either in the enteric innervation or in intestinal smooth muscle. We have studied full-thickness intestinal biopsies from 27 patients with functional intestinal obstruction due to enteric smooth muscle disease by routine histology and electron microscopy together with histochemical and immunohistochemical techniques to detect changes in the intestinal smooth muscle. Methods and results : Two patients appeared to have an acquired intestinal myopathy as a result of an autoimmune process. In 25 the disorders were congenital, of these seven had segmental abnormalities limited to the rectum and distal colon and 18 had a diffuse disease affecting both the small and large bowel. We identified five apparent histological phenotypes of enteric muscle disease, three of which represent abnormalities in morphogenesis resulting in alterations in intestinal muscle layering and two exemplify intrinsic myocyte defects and/or changes in the extracellular matrix. Conclusions : Careful phenotyping of these patients is important in devising optimal treatment and in understanding the underlying defect as well as the possible genetic mechanisms resulting in these abnormalities. Recognition of autoimmune smooth muscle disease is helpful, since making the diagnosis influences the patient's management.