A 65-year-old female, not known to have any medical illness, presented with complaints of recurrent abdominal pain for last 6 months associated with diarrhoea, subjective fever and weight loss of about 10 kg. Since last 1 month, she noticed bleeding per rectum after bowel motion with no constitutional symptoms. No palpable mass was observed on examination.
Routine portovenous phase computed tomography (CT) revealed a nearly 10 cm long affected segment of the sigmoid showing mild to moderate asymmetric mucosal thickening (5-9 mm thickening) with tapering proximal and distal edges, a small superior rectal lymph node and no obvious diverticula. No peri-colonic fluid collection or abscess was noted. No other colonic abnormality was seen. No small bowel dilatation or obstruction was noted either. Subsequent magnetic resonance imaging (MRI) of the pelvis confirmed same findings and showed a few mildly prominent adjacent lymph nodes.
Isolated sigmoid thickening at times radiologically challenging as it is a common site of diverticulitis and also colonic carcinoma particularly in elderly. Clinical presentation and imaging findings may help to narrow the diagnosis . However, if no diverticula or peri-colonic inflammatory changes are seen, the diagnosis of colonic carcinoma cannot be excluded on imaging. Colonoscopy and subsequent biopsy of our patient revealed segmental colitis associated with diverticulosis (SCAD). This case was interesting as mass-like diverticular disease can be inferred in presence of diverticula which were not found in our patient. In our case, surgeon opted for MRI as CT showed asymmetric sigmoid mucosal thickening (with no typical mural stratification sign to suggest inflammatory etiology) and colonoscopy revealed partially stensoing lesion with friable mucosa.
Also considering advanced age of patient, current admitted status, colonoscopic biopsy and laboratory results taking further few days-time, and need for local staging work-up for patient referral to specialist oncology center (in case lab/ biopsy results came out to be malignancy), decision to proceed with MRI was made. CEA levels came out to be normal. Absence of diverticula, eccentric mucosal thickening, short-segment involvement, presence of adjacent lymph nodes and shouldering of the edges on imaging have shown to favor colon carcinoma . T2W and DWI sequences in MRI have similar diagnostic value when compared to CT scanning in differentiating diverticulitis versus cancer .
SCAD is an inflammatory process that affects colonic mucosa in segments also affected by diverticulosis, and usually presents in sixth decade . No specific guidelines for its management are available, though surgery is reserved for refractory cases. Endoscopic appearance may resemble ulcerative colitis . This entity differs from inflammatory bowel disease (IBD) in regard to natural history, long term management and prognosis. Clinicians and radiologists should be aware of this entity and must include in their differential possibility of isolated sigmoid thickening.
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