Unusual type of colonic neuromuscular disorder with extensive vacuolization

Various pathological abnormalities of smooth muscle and innervation result in clinical syndromes with disordered motility of the small intestine and colon. Although these abnormalities have been extensively reported clinically, their pathologic changes and pathophysiologic mechanisms have not been well elucidated. We report a case of visceral neuropathy with secondary muscle changes in a 7-yr-old ventilator dependent, mentally retarded child who presented with a history of chronic constipation and symptoms of intestinal obstruction. The muscle layer of the colectomy specimen showed extensive infiltration of vacuolated cells that were positive for S-100 and synaptophysin but negative for glial fibrillary acidic protein (GFAP) and neural filament protein (NFP). Calretinin positivity was preserved in submucosal ganglion cells but was absent in vacuolated nerve branches. Masson's trichrome stain showed evidence of fibrosis, indicative of muscle damage. There was a reduced number of intestinal cells of Cajal in the muscularis propria, as indicated by CD117 (c-kit) immunostaining. This disorder is most likely a sporadic visceral neuropathy, secondarily affecting muscular function, that causes colonic pseudo-obstruction.