Treatment Options for Microscopic Colitis

Arthur M. Barrie, MD, PhD

Disclosures

March 18, 2016

Case Presentation

A 64-year-old woman reports a 9-month history of watery, nonbloody diarrhea with up to five loose bowel movements a day. Her diarrhea is associated with mild, crampy abdominal pain that is relieved with her bowel movements.

Onset of her diarrhea occurred while caring for her dying father, during which time the patient blamed "stress," but the symptoms persist. The patient denies preceding travel, sick contacts, unusual ingestions, and antibiotic use. Fasting seems to reduce her diarrhea, and her diet is gluten- and dairy-restricted, but this has not alleviated her symptoms. The patient also has tried bismuth subsalicylate and loperamide; the latter provides partial, transient relief from her diarrhea.

The patient's medical history is significant for hypothyroidism with hormone replacement therapy and osteoarthritis of her hands and knees, for which she uses ibuprofen on a regular basis. The patient takes no other medications and has never had surgery.

The patient has no family history of gastrointestinal disease, including celiac disease and inflammatory bowel disease.

The patient's physical exam is normal. A complete review of symptoms is negative, and the patient denies extraintestinal manifestations, including weight loss and fever.

Laboratory evaluation for the patient's chronic diarrhea, as ordered by her primary care physician, included a complete blood count, metabolic panel, celiac serology, and thyroid testing and revealed relatively normal findings. Of note, C-reactive protein was mildly elevated, whereas the erythrocyte sedimentation rate was normal. Stool studies for pathogens were negative, including for ova and parasites, such as Giardia and Cryptosporidium.

On the basis of the patient's history and physical exam, you suspect that she has microscopic colitis (MC) because many of its characteristic features are present, including gender (female predominance), age (older than 60 years), the nature of the diarrhea (chronic and watery), and other risk factors (regular use of a nonsteroidal anti-inflammatory drug). MC also is one of the most common causes of chronic watery diarrhea in developed countries, with a reported prevalence of 48-219 per 100,000 persons.[1]

To confirm a diagnosis of MC, a colon biopsy is required; therefore, colonoscopy is recommended as the next step in the patient's evaluation. Colonoscopy to the terminal ileum is normal in endoscopic appearance, which is typical for MC. Random biopsy samples are obtained from the left colon and, more important, from the right colon; biopsy samples from the distal colon may miss the diagnosis of MC, because the disease tends to be more severe and diffuse in the right colon.

The pathology report confirms your clinical suspicion: The colon biopsy samples demonstrate lymphocytosis in the epithelium and lamina propria, as well as a thickened subepithelial collagen band. The latter feature is consistent with a diagnosis of collagenous colitis, one of the two types of MC. The other type of MC is lymphocytic colitis, which lacks the prominent collagen band.

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