Microscopic colitis, a forgotten condition: a clinical case and review of the literature.

Microscopic colitis is a not uncommon chronic inflammatory disease of the colon, characterized by watery, non-bloody diarrhea, which is often forgotten and misdiagnosed. In this paper, we present a puzzling case of relapsing chronic diarrhea triggered by non-steroidal anti-inflammatory drug (NSAID) abuse, smoking, inappropriate antibiotic use, and secondary Clostridium Difficilis infection. Several tests were performed during hospitalization, all of which were negative apart from fecal calprotectin (> 6,000 mg/kg, normal values < 50 mg/kg) and a positive Clostridium Difficilis toxin test. Since Vancomycin treatment did not bring about the expected response, colonoscopy was performed, which led to diagnosis, targeted therapy, and clinical resolution. Targeted therapy with budesonide and probiotics was initiated leading to resolution of the diarrhea. This case study shows how actual diagnosis may be delayed not only due to having to perform differential diagnosis with chronic inflammatory diseases, but also because certainty can only come from histological evidence, which takes time to obtain, especially when the disease's multifactorial nature is considered (smoking, NSAID abuse, oral proton pump inhibitors, inappropriate antibiotic use, and Clostridium difficilis infection).