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 ga nglionitis in the myenteric plexus of the large bowel and ileum, whereas th e submucosal plexus was spared. At this time, antineuronal nuclear antibodi es (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 inflammatatory 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 fullfilling definin g criteria for ANNA-1. The serum also reacted with antigens of defined mole cular weight in a Western blot, thus fullfilling defining criteria for anti -Hu. Expression of the Huantigen could be visualized in the nuclei of the p atient's tumor cells by immunohistochemistry. These tests showed that an an titumor inflammatory response was the cause of the bowel disease. This is t he first report of a tumor from the neuroblastoma group that caused paraneo plastic intestinal pseudoob-struction. Ganglionitis and subsequent aganglio nosis are the hallmark of the morphologic diagnosis which cannot be obtaine d by suction biopsy in patients with intact submucosal plexus. Instead, ser um testing for autoantibodies can reveal the etiology.