Idiopathic Segmental Megacolon-Intestinal Neuronal Dysplasia Type B, Cajal Cells Abnormality, or Still "Idiopathic" Disease?-Case Report and Literature Review.

Abstract

Background and Clinical Significance: Idiopathic megacolon (IM) in adults is a rare disease with an unknown aetiology. The condition remains poorly understood, with ongoing debate over the specificity of its histopathology. Case Presentation: Case 1: A 40-year-old man was admitted due to moderate lower abdominal pain and a distended, asymmetric abdomen. X-ray demonstrated the sigmoid colon with a diameter of 13 cm. Colonoscopy found a significantly enlarged and elongated sigmoid colon, which precluded the examination of the entire colon due to the insufficient length of the colonoscope. All blood assays were within the normal range. Intraoperatively, there was a significantly dilated sigmoid colon measuring 20 cm in width with a length of 60 cm. A sigmoid resection with mechanical T-T anastomosis between the descending colon and proximal rectum circular stapler was performed. The patient had an uneventful recovery. Seven years after the operation, he is symptom-free. The histopathological examination revealed a slight oedema of the lamina propria, submucosal fibrosis, hyperplastic submucosal ganglia and nerve fibres, hypertrophy of the muscle layers and hyperplastic myenteric nerve plexuses and ganglion cells. Case 2: A 28-year-old otherwise healthy man was admitted due to intermittent diffuse abdominal pain that manifested suddenly during a military mission. There was no remarkable medical history. The abdominal contrast CT revealed a segmental sigmoid megacolon with a diameter of 10 cm without any other noteworthy pathology. All organic causes for megacolon were excluded. No conservative treatment was applied. The intraoperative finding was a dilated sigmoid measuring 15 cm in diameter. A sigmoid resection was performed, followed by T-T anastomosis between the descending colon and proximal rectum. During the postoperative course, there was significant anastomotic bleeding, which was managed successfully by blood transfusion and haemostatic clips. The patient was discharged on the 8th postoperative day. Eighteen months after the operation, he is symptom-free. The histopathological examination was performed using Formalin-Fixed Paraffin-Embedded (FFPE) tissue, cut at 3 µm. Immunohistochemistry was performed on an autostainer Leica Bond with ready-to-use reagents-CD117 clone EP10 and S100 clone EP32. The dilated part revealed a fibrotic submucosa with hyperplastic vessels and nonspecific inflammatory changes, hypertrophy of the muscle layers, and hyperplastic submucosal and myenteric ganglia and plexuses, but did not fulfil the criteria for IND. The same picture was observed in both the distal narrowed part and the resection lines. There was no obvious abnormality of the Cajal cells in both parts of the specimen. Conclusions: We were unable to identify a specific cause of IM in the presented cases. The histopathological findings were not compatible with IND, Hirschsprung disease, or other neuromuscular pathology. The critical analysis of the literature does not support IND as a possible cause of IM. Due to the heterogeneity of colonic motility disorders and the lack of a consistent histological pattern in IM, we hypothesise that it has a multifactorial aetiology.