Clinical History
Young male patient with history of previous ileocaecal resection and recent (3 months earlier) enteric stricturoplasty for Crohn’s disease, admitted to Emergency Department with fever, clinical and laboratory abnormalities consistent with acute disease relapse.
At physical examination a painful, reddish focal skin bulge was noted on his right anterior abdomen.
Imaging Findings
Urgent contrast-enhanced CT was requested “to rule out abdomino-pelvic abscess collections” and acquired with intravenous contrast injection following peroral bowel opacification.
In the site of previous limited ileocaecal resection, nondistended convergent loops with mural thickening were interpreted as consistent with recurrent Crohn’s disease, closely adherent to the peritoneal serosa and inner abdominal wall. A fluid-containing fistulous track with enhancing borders was seen crossing the muscular and fascial planes of the anterior abdominal wall and through the subcutaneous fat, to reach the skin.
Active purulent drainage and fistulous orifices were excluded clinically, and surgical revision including enterocutaneous fistula debridement was planned.
Discussion
Crohn’s disease (CD) patients commonly develop pyogenic complications such as perianal and internal abdominal fistulas and abscesses, due to the characteristic transmural chronic inflammation of the intestinal wall leading to penetration into adjacent tissues. The same pathogenetic mechanism can explain fistulisation of affected enteric loops to the anterior abdominal wall, crossing through the subcutaneous fat planes and ultimately reaching the skin. The vast majority of enterocutaneous fistulas communicate with the affected ileum and are associated with long-standing and/or active inflammatory CD. Otherwise, sometimes fistulisation can occur through a previous abdominal scar usually within a few months from surgery [1, 2].
Compared to the past decades, currently enterocutaneous fistulas represent very rare complications of CD, associated with significant morbidity including bowel obstruction, abscess formation, diarrhoea, malabsorption and weight loss. Inflammatory involvement of the superficial planes of the abdomen is usually evident at physical inspection, particularly when associated with intermittent purulent discharge [1-3].
Optimal treatment of enterocutaneous fistulas in CD is debated, since most series include few affected patients. Immediate surgery with resection of the diseased bowel segment, debridement of the fistulous tract through the abdominal wall and subcutaneous planes has been advocated, particularly in actively draining lesions. Conversely, spontaneous closure has been reported in up to half of patients with bowel rest, total parenteral nutritional support and peristomal skin care associated with medical therapy of the underlying CD.
In the past, fistulography with direct iodinated contrast injection was performed to depict enterocutaneous fistulas, without the possibility to identificate the involved anatomical planes [2, 4]. As this case exemplifies, nowadays enterocutaneous fistulas may be occasionally detected during cross-sectional imaging follow-up of CD patients with CT or MR enterography. These abnormalities may be unexpected or subtle, therefore it can be suggested that the anterior abdominal wall should be carefully scrutinised when reviewing diagnostic studies of active CD.
Differential Diagnosis List
Enterocutaneous fistula in Crohn's disease
Abdominal wall abscess
Foreign body granuloma
Final Diagnosis
Enterocutaneous fistula in Crohn's disease
