S2306 Bad to the Bone: A Rare Case of Fistulizing Disease Extending to the Sacrum

Abstract

INTRODUCTION: Fistula formation commonly occurs between intestines and other epithelial-lined hollow organs such as the bladder, skin, vagina, or other regions of the gastrointestinal tract. Infrequently, a connection can form between the bowel and the vertebral column and lead to vertebral osteomyelitis. We present the case of a young male with significant abdominal pathology found to have sacral osteomyelitis in the setting of fistula formation between the small bowel and sacrum. CASE DESCRIPTION/METHODS: A 27-year-old male with a history of opioid dependence and abdominal gunshot wound requiring subtotal colectomy with ileo-rectal anastomosis presented with progressive, bloody diarrhea and poor appetite. The patient reported history of previous colonoscopies with balloon dilations of strictures but never diagnosed with inflammatory bowel disease (IBD) or started on any therapies. On exam, the patient was emaciated with multiple clean abdominal scars and diffuse, mild abdominal tenderness. Labs showed microcytic anemia with hemoglobin of 8, elevated fecal calprotectin (402) and CRP (15.1) without leukocytosis, and negative tissue transglutaminase. His stool studies and gastrointestinal pathogen panel were negative for Clostridium difficile or other pathogens. Computed Tomography of the abdomen found enteritis and proctocolitis and concern for possible osteomyelitis of the sacrum and coccyx. Magnetic resonance enterography found multiple entero-colonic fistulas and active inflammatory disease of the small bowel, inflammation of the sacral nerve roots, and concern for fistulization between the small bowel and sacrum. Subsequent flexible sigmoidoscopy found ulcerated friable mucosa and pseudomembranes in the rectum. Pathology showed nonspecific chronic inflammation and was negative for Clostridium difficile. He was started on Rifaximin for empiric treatment of small intestinal bacterial overgrowth with improvement in diarrhea and is planned for further IBD workup to assess the status of his fistulizing disease. DISCUSSION: While most enteric fistulas occur due to prior abdominal surgery complications, 10-15% occur from inflammation and infection associated with Crohn’s disease. Rarely, fistulas can develop between bowel and vertebra, and osteomyelitis may result due to translocation of gut flora from the intestine to the spine via the fistula as seen in our patient. Ultimately, this uncommon presentation should prompt investigation into etiology and use imaging to guide aggressive management.Figure 1.: Rectal ulcer seen on flexible sigmoidoscopy.Figure 2.: MRE showing evidence of a fistula from the small bowel to the sacrum.