Collagenous Enterocolitis: A Rare Condition with Simultaneous Involvement of the Upper and Lower Gastrointestinal Tract

Abstract

Collagenous colitis is a form of microscopic colitis, while Collagenous Sprue (CS) is a malabsorptive disorder that mimics celiac disease. Both conditions show increased Intraepithelial Lymphocytes (IELs) and basement membrane thickening due to collagen deposition. The simultaneous occurrence of both disorders is rare, and only a few such cases have been reported in the literature. A 60-year-old female presented with chronic, non bloody diarrhoea persisting for two years. Investigations revealed megaloblastic anaemia and hypoalbuminaemia. Gastroenteroscopy showed flattening and atrophy of the small intestinal mucosa. Biopsy results showed increased IELs, normal crypt architecture, and stripping of the epithelium. There was also patchy deposition of hyalinised band subepithelially, confirmed to be collagen through Masson’s stain. As both the upper and lower Gastrointestinal (GI) tracts were involved, a diagnosis of collagenous enterocolitis was made. A 70-year-old female presented with intermittent watery diarrhoea for the past 10 days, accompanied by urgency and tenesmus. She had a history of colicky abdominal pain four years ago, which improved with steroids, but the symptoms recurred. Clinically, she was considered to have inflammatory bowel disease, with recurrent anaemia. Both gastroduodenoscopy and colonoscopy were normal. Mapping biopsy showed increased IELs and focal atrophy in the duodenum, while the colon exhibited mild mononuclear inflammation with occasional minimal activity. Focal, irregular deposition of subepithelial collagen was also observed and confirmed through Masson’s stain. A diagnosis of collagenous enterocolitis was made. She is currently being monitored for any recurrence of symptoms, after which steroid treatment will be initiated. Collagenous colitis, CS, and collagenous duodenitis share similar histological features and can rarely co-exist. Further studies are needed to better understand their aetiology and association.