Spontaneous Colocutaneous Fistula: A Rare Presentation Of Colon Carcinoma

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Colocutaneous fistula is a rare clinical condition and more often than not it is the result of surgical misadventures. The spontaneous form of this fistula is a still rarer entity that occurs usually in patients with diverticulitis or Crohn's disease. We report a patient, a 75-year-old male, who presented to us with spontaneous colocutaneous fistula secondary to carcinoma of the descending colon. CASE REPORT A 75-year-old male presented with the complaint of a painful swelling over the left loin since 7 days. The swelling opened spontaneously 4 days later discharging foul smelling purulent material (figure 1). Figure 1 Figure 1: Preoperative view of the patient showing a faecal fistula over the left loin The swelling was associated with fever. There was no history of trauma or previous surgery. There was no history of bowel symptoms or abdominal pain. Past history was insignificant except for treatment taken for multibacillary leprosy 2 years back. On examination, there was an ulcer of about 5x5cm over the left loin below the costal margin with feco-purulent discharge, erythematous skin surrounding the ulcer, a floor covered with slough and indurated base and edges. General examination revealed pitting pedal edema. Examination of the abdomen and other systems did not reveal much. Blood investigations were normal except for hypoalbuminemia. Barium enema revealed a colocutaneous fistula from the descending colon (figure 2). Figure 2 Figure 2: Barium enema picture demonstrating extravasation of contrast medium from the proximal sigmoid colon or distal descending colon Colonoscopy revealed an ulcerated endophytic growth about 40cm from the anal verge, which was biopsied and was reported as tubulovillous adenoma with severe dysplasia Spontaneous Colocutaneous Fistula: A Rare Presentation Of Colon Carcinoma 2 of 4 with adjacent invasive malignancy. Ultrasonography of the abdomen revealed bowel wall thickening in the left lumbar region. With these findings, the patient underwent exploratory laparotomy and left hemicolectomy with excision of a rim of the abdominal wall at the site of the fistula (fig. 3, 4). Figure 3 Figure 3: Intraoperative demonstration of the fistula site after mobilizing the descending and transverse colon Figure 4 Figure 4: Resected specimen of colon with fistula Histopathological examination of the specimen was reported as adenocarcinoma of the colon. Postoperatively, the patient was referred to the department of oncology for chemoradiation.