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Collagenous colitis and Crohn's disease: Guilty or innocent bystander?

Digestive and Liver Disease, Volume 48, Issue 10, October 2016, Pages 1261 - 1262

Dear Editor,

The authors report a case of a 73-year-old male evaluated for profuse watery diarrhea and weight loss for 2 months, aggravated the week before. His past medical history was relevant for ileal Crohn's disease diagnosed at the age of 34 years, with two segmental enterectomies due to ileal stenosis and enterocutaneous fistula. The histopathological exam of the resected bowel showed transmural lymphoplasmocytic infiltrate with deep ulceration and non-caseating granulomas. Due to penetrating phenotype, immunomodulatory therapy was proposed but the patient refused.

He was taking mesalazine (3 g daily), although with bad compliance. His last colonoscopy, which did not showed any lesion, had been performed nearly 10 years before presentation and since than the patient refused to undergo further endoscopic revaluations.

He had no history of abdominal pain, fever or use of non-steroidal anti-inflammatory drugs (NSAIDs), proton-pump inhibitors or antidepressants. Laboratory tests showed anemia with iron, folic acid, vitamin D and K deficiency and severe electrolyte disorders with hypomagnesemia (0.15 mmol/L), hypocalcemia (0.6 mmol/L) and hypokalemia (K+ of 2.2 mmol/L). The presence of celiac disease was excluded with negative duodenal biopsies and normal celiac panel.

The patient was admitted in an intermediate care unit with a presumptive diagnosis of Crohn's disease flare and started prednisolone (40 mg per day), iv fluids and correction of the electrolytic disorders. Stool cultures were negative. An ileocolonoscopy was performed and revealed two strictures of the neoterminal ileum, one of which required endoscopic through the scope (TTS) balloon dilation, without other endoscopic lesions of the ileal or colonic mucosa. The histopathological exam of the biopsy specimens of the right and left colon revealed an increased surface intraepithelial lymphocyte count and a collagenous band (Fig. 1), confirming the diagnosis of collagenous colitis.


Fig. 1

Collagenous colitis: presence of thick subepithelial bands of collagen deposits (HE; A: 100×, B: 200×).


The patient presented progressive improvement and was discharged under a steroid-tapering regimen and mesalazine. Three months after he was readmitted in an intermediate care unit due to profuse watery diarrhea with impaired consciousness, severe electrolytic disorders and acute kidney injury. A recurrence of collagenous colitis was admitted and the patient started oral budesonide therapy, with symptoms resolution.

Microscopic colitis is a chronic inflammatory bowel disease (IBD) characterized by chronic nonbloody diarrhea and characteristic microscopic features [1]. The etiology and pathophysiology is not well understood but is likely to be multifactorial, involving mucosal immune responses to luminal factors in a genetically predisposed individual [1]. A wide array of conditions (autoimmune, metabolic, neoplastic and drug-related) are associated with collagenous colitis [2]. Also, associations between collagenous colitis and other IBD have been rarely reported in the same patient [3], [4], and [5]. Bohr et al. [3] reported three cases of collagenous colitis up to thirty-two years after the diagnosis of Crohn's disease. The association between the two diseases might occur due to chance alone [3] and [4]. Moreover, differences in genetic and other factors suggest that collagenous colitis has a separate etiology and/or pathogenesis, distinct from other IBD [4].

The histological features encountered in microscopic colitis are not pathognomonic and may be seen in a variety of inflammatory conditions in the gastrointestinal tract, including IBD, infections, and as an adverse effect of several drugs [2]. Separation of microscopic colitis from ulcerative colitis and Crohn's disease is made on the basis of a different constellation of clinical and endoscopic findings [2]. Difficulty does arise when IBD precedes lymphocytic or collagenous colitis. In these rare instances, strict adherence to diagnostic criteria and careful correlation with clinical and endoscopic features are essential to prevent a misdiagnosis of collagenous colitis in the context of previous or pre-existing IBD [2].

The development of collagenous colitis after Crohn's disease diagnosis is an association rarely reported in the literature. It remains unclear if the association between the two diseases is only coincidental or not. Studies are still needed to elucidate possible similarities and differences in the pathogenic features of collagenous colitis and Crohn's disease.

Conflict of interest

None declared.


  • [1] A. Münch, C. Langner. Microscopic colitis: clinical and pathologic perspectives. Clinical Gastroenterology and Hepatology. 2015;13:228-236
  • [2] R. Chetty, D. Govender. Lymphocytic and collagenous colitis: an overview of so-called microscopic colitis. Nature Reviews Gastroenterology & Hepatology. 2012;9:209-218
  • [3] J. Bohr, C. Tysk, S. Eriksson, et al. Collagenous colitis: a retrospective study of clinical presentation and treatment in 163 patients. Guy. 1996;39:846-851
  • [4] H.J. Freeman, K.W. Berean, M. Nimmo. Evolution of collagenous colitis into severe and extensive ulcerative colitis. Canadian Journal of Gastroenterology. 2007;21:315-318
  • [5] F.M. Giardiello, F.W. Jackson, A.J. Lazenby. Metachronous occurrence of collagenous colitis and ulcerative colitis. Gut. 1991;32:447-449


Department of Gastroenterology, Faculty of Medicine of the University of Porto, Porto, Portugal

Department of Emergency – Centro Hospitalar São João, Faculty of Medicine of the University of Porto, Porto, Portugal

Department of Gastroenterology, Faculty of Medicine of the University of Porto, Porto, Portugal

Corresponding author at: Gastroenterology Department, Centro Hospitalar São João, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal. Tel.: +351 225 512 100; fax: +351 225 025 766.