Perforated Sigmoid Colon Adenocarcinoma with Concomitant Intestinal Ascariasis: Coincidence or Association? A Case Report.

Abstract

Background:
Colorectal carcinoma and intestinal ascariasis are both encountered in tropical and low-resource settings. However, their simultaneous occurrence in a single surgical case is rarely reported. Ascaris lumbricoides is not classified as a proven carcinogenic helminth and its relationship with colorectal carcinoma remains uncertain.

Case Presentation:

An elderly woman presented with features of acute abdominal pain and generalized peritonitis. Contrast-enhanced computed tomography showed free intraperitoneal air and fluid, mural thickening of the sigmoid and descending colon and a loculated peri-sigmoid collection. These imaging features were suggestive of hollow viscus perforation. An emergency laparotomy was done which showed faeculent peritoneal contamination and a perforated sigmoid mass adherent to the urinary bladder. Sigmoidectomy with end colostomy was performed. During bowel examination, three adult Ascaris lumbricoides worms were retrieved from the small intestine. Histopathology confirmed well-differentiated adenocarcinoma of the colon invading up to the serosa, staged as pT4aN0, AJCC 8th edition. The appendix showed acute appendicitis and was free of tumour. The patient received albendazole along with standard postoperative care.

Conclusion:
This case represents rare coexistence of perforated sigmoid colon adenocarcinoma and intestinal ascariasis. The perforation was most likely attributable to transmural tumour invasion, while ascariasis was most likely incidental. The case highlights the need for careful intraoperative assessment and mandatory histopathological examination, as parasitic infestation should not obscure an underlying malignancy.