{'fraction_non_alphanumeric': 0.022642784724569112, 'fraction_numerical': 0.006083136194660358, 'mean_word_length': 5.210912906610703, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 1, 'zh_pornsignals.json': 0}}
Segmental Hypoganglionosis of the Colon: A Case Report

A 64-year-old woman was admitted to hospital with persistent abdominal pain. She had been hospitalized with similar symptoms on five occasions during a period of 2 years. Computed tomography revealed dilatation and fecal impaction from the ileum to the transverse colon. A barium enema and simultaneous ileus tube radiography showed a narrow segment of descending-sigmoid colon. Colonoscopy showed no mucosal change. Her symptoms did not improve with conservative therapy, so descending and sigmoid colectomy was performed. Histologic examination showed disappearance of ganglion cells; axon of Meissner’s plexuses was present, and the number of Auerbach’s plexuses was decreased. The definitive diagnosis was segmental hypoganglionosis (SH) of the colon. The postoperative course was uneventful, and the functional result was positive at 1 year postoperatively. SH is extremely rare; however, surgical intervention is expected to be of benefit. Therefore, it is important to keep SH in mind when treating patients with chronic obstruction of the left side of the colon. (J Nippon Med Sch 2021; 88: 370―374)


Introduction
Segmental hypoganglionosis (SH) is a rare condition.
One of the main symptoms of SH is chronic intermittent obstruction caused by partial expansion failure of the intestine, wherein the numbers of neural plexuses and ganglion cells are decreased in the submucosal or intramucosal layers 1,2 . SH is sometimes regarded as a subtype of colonic pseudo-obstruction or as a disease similar to adult Hirschsprung disease, but the term is controversial. Because definitive diagnosis is only possible by determining the histochemical characteristics of a fullthickness biopsy specimen, it can be difficult to diagnose preoperatively. This study reports a surgical case of SH in which the patient had longstanding recurrent obstruction symptoms.

Case Report
A 64-year-old woman was admitted to hospital for assessment of severe abdominal pain and constipation during the previous few days. She had been prone to consti-pation for several years, occasionally used laxatives, and had previously been admitted to hospital with similar symptoms five times in the past 2 years. Her medical and family histories were unremarkable. Physical examination showed gross abdominal distention, moderate tenderness in the epigastrium, and no rebound tenderness.
Bowel sounds were active and showed no increase. Laboratory findings, including a white blood cell count and C-reactive protein, were normal. An abdominal X-ray showed the multiple air-fluid level of the ileum and colon dilatation across the entire abdomen. Abdominal computed tomography (CT) revealed dilatation with feces present from the ileum to the transverse colon. The dilated transverse colon was elongated, but there was no significant obstruction and no sign of tumor lesions (Fig.   1). Colonoscopy revealed a narrow segment in the descending colon and sigmoid colon with intact mucosa (Fig. 2). Ileus tube radiography and barium enema were performed simultaneously and revealed a narrow segment in the descending colon and sigmoid colon with  spastic change and diverticula and a dilated colon and ileum above the stricture (Fig. 3). Conservative therapy with fasting and ileus tube radiography was effective; however, surgery was proposed owing to the patient's recurrent symptoms. The patient and her family provided informed consent.
Intraoperatively, we noted a significantly dilated and redundant ascending and transverse colon (Fig. 4). The descending and sigmoid colon were both spastic and hard, the intestinal diameter was remarkably small, and diverticulitis was present. This area was considered to be responsible for the disease, so it was decided that the lesion between the middle of the transverse colon and sigmoid colon would be removed. We performed primary anastomosis by functional end-to-end anastomosis. Because of the considerable risk of leakage from the dilated intestine, we added a buried suture to staple line and performed decompression by ileus tube radiography perioperatively, to further prevent anastomotic leakage. The transverse colon was markedly dilatated, to 14 cm in diameter, while the descending colon was 4.5 cm, and there was no tumor lesion in the mucosa (Fig. 5a). Histologic examination revealed no ganglion cells or fibers in Meissner's plexuses, and the number of Auerbach's plexuses was diminished, with a degenerative tendency of the ganglion cells in the narrow segment ( Fig. 5b-e). Surgery is considered the definitive treatment for SH 11 .
The stricture site alone may be resected 7,12 , but some cases require subtotal proctocolectomy for marked dilatation or   There have been similar cases in which only the dilated segment was resected because SH was not considered to be the cause preoperatively. This also included cases in which the main lesion was not completely resected, resulting in postoperative recurrent stricture, and cases in which the anal margin included the lesion, thus causing anastomotic stricture. Rapid pathological diagnosis was difficult because ganglion cells were disseminated and examination of ganglion cells in the long axis of the intestine was necessary. We thus secured a centimeter margin from the stricture site. Detailed pathological examination of the resected specimen is necessary for assessing neural abnormality in SH; thus, it is important to pay attention to clinical features such as recurrent bowel obstruction without organic obstruction and laboratory findings, to include SH in the preoperative differential diagnosis, and to plan therapeutic strategies accordingly.
To establish diagnostic criteria for SH, future cases such as these should be investigated.
We reported a case of SH in which surgical treatment after a long symptomatic period allowed for histopathological diagnosis.