Autoaggressive inflammation of the myenteric plexus resulting in intestinal pseudoobstruction

After a 3-year history of severe constipation, a 16-year-old girl required surgery to be relieved of impacted stools. Histologic examination showed ganglionitis in the myenteric plexus of the large bowel and ileum, whereas the submucosal plexus was spared. At this time, antineuronal nuclear antibodies (ANNA-1, anti-Hu) were found at high titer in the serum of the patient. One and a half years earlier, a paravertebral ganglioneuroblastoma had been removed. Histologic examination had shown undifferentiated neuroblasts and morphologically mature ganglion cells with both cell types embedded in an inflammatory infiltrate morphologically similar to the lymphoplasmocytic infiltration seen in the myenteric plexus. The patient's serum was found to bind to nuclei of mouse intestinal tract neurons, thus fulfilling defining criteria for ANNA-1. The serum also reacted with antigens of defined molecular weight in a Western blot, thus fulfilling defining criteria for anti-Hu. Expression of the Huantigen could be visualized in the nuclei of the patient's tumor cells by immunohistochemistry. These tests showed that an antitumor inflammatory response was the cause of the bowel disease. This is the first report of a tumor from the neuroblastoma group that caused paraneoplastic intestinal pseudoobstruction. Ganglionitis and subsequent aganglionosis are the hallmark of the morphologic diagnosis which cannot be obtained by suction biopsy in patients with intact submucosal plexus. Instead, serum testing for autoantibodies can reveal the etiology.