eP585 - An Unusual Presentation of Amebic Toxic Megacolon: A Clinical Case Report

Purpose/Background: Toxic megacolon is an underreported disease with high heterogeneity in its diagnostic criteria and presentation. The mortality rate of the disease has been reported as high as 30%. The etiology is also diverse most of them seen in inflammatory bowel disease (IBD) or infectious disease(1). . Amebic colitis caused by Entamoeba Histolytica is a highly prevalent disease in endemic areas such as Central and South America. Only 10% of the patients with the disease present with complications such as colon perforation and it has been reported as a rare cause of toxic megacolon. Therefore, in non-endemic areas, the diagnosis and treatment of this condition can be misdiagnosed with other conditions such as IBD which has similar clinical and endoscopic findings. Clinical criteria to diagnose toxic megacolon due to amebic disease is not clear and often confirmed with pathological reports after surgical management with subtotal colectomy. Therefore, the description of cases and reporting of clinical, surgical, and pathological findings is relevant to increase awareness and improve the management of these conditions. We present this clinical case of a patient misdiagnosed with appendicitis with a toxic megacolon due to amebic colitis.Methods/Interventions: We present an otherwise healthy 45-year-old male, resident of Canada who began 1 month prior to his arrival with chronic diarrhea (Bristol 7) with a positive stool microscopy of entamoeba histolytica. The patient decided to travel to Mexico, to a private health institution to continue his workup. Laboratory analysis and a CT abdominal scan with IV contrast were performed. He was diagnosed with acute appendicitis, the patient underwent a laparoscopic appendicectomy and presented a reported grade II adverted cecum lesion, an infraumbilical laparotomy, and a primary repair was made, the patient was discharged 2 days afterward, and 4 days postoperative care, he came into our institution. A new CT abdominal scan was made and reported a transverse colon dilatation of up to 8.5 cm.
A clinical diagnosis of toxic megacolon due to amoebic colitis was made. The patient was sent to a colonoscopy where multiple ulcers and intestinal mucosae with suspicion of transmural ischemia. He was sent into the operating room right after.
An exploratory midline laparotomy was made, and present was a dehiscent repair of the grade ii cecum lesion with multiple ischemic lesions in the whole extension of colonic tissue. a subtotal colectomy with terminal ileostomy and Hartmann procedure was made.Results/Outcomes: The histopathological report revealed ulcerated colitis associated with the presence of morphological structures compatible with entamoeba histolytica trophozoites with erythrocytes inside. The patient continued to deteriorate, presenting refractory septic shock and progressing to multiorgan failure with renal, hepatic, and cardiovascular systems. Despite the intents of the medical and surgical team, the patient is deceased.Conclusion/

Discussion: This clinical case represents the worst outcome after the misdiagnosis of a toxic megacolon. This disease should be suspected in individuals with chronic diarrhea, dysentery, and images with significant colon dilatation. In addition, patients with evidence of a symptomatic amebic disease should be treated promptly before other pathology is attributed to the patient clinical picture. We hope this clinical report will help surgeons from amebic endemic and non-endemic regions to get an efficient diagnosis to improve the prognosis of patients with this condition.Macroscopic pathology image and tomographic findings of megacolonLeft: An anterior view of the total colectomy is presented. It can be observed the cecum with the previous adverted Grade II lesion. Right: CT-scan representing image of the transverse colon with a maximal diameter of 8.56 cm