Isolated jejunal Crohn\'s disease

Clinical History

A 28-year-old male patient was being treated elsewhere for suspected abdominal tuberculosis with no relief in symptoms in spite of being on anti-tubercular regimen for the past 8 weeks. He was referred to us with worsening crampy abdominal pain, recurrent diarrhoea and persistent weight loss.

Imaging Findings

CT abdomen revealed isolated long-segment proximal jejunal involvement in the form of circumferential mural thickening and luminal effacement. The jejunum proximal to the involved segment was dilated. The interface of the bowel with adjacent mesenteric-fat was indistinct with associated mesenteric-fat proliferation (Creeping Fat sign). The vasa-recta appeared prominent and dilated giving rise to the typical Comb-Sign. Remaining bowel including the ileo-caecal and gastro-duodenal junction were unremarkable.

In view of the above radiological findings, keeping Crohn's disease in mind, an enteroscopy was performed which revealed stenosed and erythematous jejunum with proximal dilation. Biopsies revealed non-specific inflammatory changes. PCR for mycobacterium tuberculosis were negative; while anti-saccharomyces-cerevisiae antibodies were strongly positive. Based upon the clinicoradiological findings the patient was started on steroids and his symptoms improved dramatically in a period of 2 weeks. A repeat enteroscopy revealed significant reduction in the inflammation and this time the scope could be negotiated beyond the involved segment.

Discussion

Crohn’s disease is an inflammatory bowel disease characterised by chronic transmural inflammation that may involve any part of the digestive tract from mouth to anus, mostly found in the terminal ileum, the caecum, and the proximal colon. Five types of Crohn's disease based on the gastrointestinal area affected have been described. These include: (i) Gastroduodenal Crohn's; (ii) Jejunoileitis; (iii) Ileitis; (iv) Ileocolitis (one of the commonest); and (v) Granulomatous colitis. Isolated jejunal involvement in adults is definitely a rare occurrence representing only approximately 1% of cases of Crohn’s with limited case reports available in the literature [1-3].

Imaging findings in jejunal Crohn’s are no different. Typical imaging findings include bowel wall thickening with mural stratification (during the active phase) leading to a target or double-halo appearance. During the active phase the inflamed mucosa and serosa frequently shows avid contrast enhancement. The mural stratification fades in long-standing disease and the bowel wall appears more or less homogeneous. The mesentery is often involved and frequently displays the typical creeping fat sign referring to the separation of bowel loops owing to fibrofatty proliferation of the mesenteric fat. Mesenteric fat attenuation is generally raised with hazy interface of the involved bowel with the mesentery representing inflammatory changes taking place in the mesenteric fat. Mesenteric lymph nodes usually ranging between 3 to 8 mm in size can also be seen. Presence of comb sign at imaging represents hypervascularity of the mesentery in the active stage. This refers to the prominence and dilatation of the of the vasa recta. Complications such as fistulae are reportedly less frequent in patients with jejunal Crohn's. It has been stated that perhaps the inherent probability of Crohn's disease to fistulise increases with a progressively distal location in the gastrointestinal tract [6]. Another study states that jejunal Crohn's disease is associated with a higher rate of early disease recurrence (in post-operative patients) compared to ileocaecal disease but long-term recurrences rate do not differ significantly between the two [5].

Often the diagnosis of inflammatory bowel disease depends on a combination of clinical, radiological, endoscopic, serological, and histologic criteria [7]. Anti-Saccharomyces-cerevisiae-antibodies (ASCA), along with perinuclear-antineutrophil-cytoplasmic-antibodies (pANCA), are among the two most useful discriminating serological markers for colitis. ASCA tends to recognize Crohn's disease more frequently, whereas pANCA tend to recognize ulcerative colitis [7]. ASCA has been reported to be a specific marker for proximal Crohn’s and for a more severe disease phenotype [8].

Differential Diagnosis List

Final Diagnosis

Isolated jejunal Crohn's disease

URL:	https://eurorad.org/case/9455
DOI:	10.1594/EURORAD/CASE.9455
ISSN:	1563-4086