Background Microscopic colitis (MC) is an inflammatory condition of the colon characterised by chronic or intermittent diarrhoea with normal endoscopic appearance of the colonic mucosa. Its prevalence is estimated at 4-13% of patients with chronic diarrhoea and usually affects adults, with a mean age at diagnosis of 60.7 years. MC is traditionally divided into 2 histological subtypes, lymphocytic colitis [LC] (>15-20 intraepithelial lymphocytes per 100 enterocytes, with mixed inflammatory infiltrate in the lamina propia and normal crypt architecture) and collagenous colitis [CC] (presence of a thickened subepithelial collagen band and inflammatory changes similar to those of LC), although overlap between both may occur in up to 26%. Its etiology is unknown, but is often associated with systemic and organ-specific autoimmune diseases (AD) and the intake of drugs (NSAIDs, proton pump inhibitors, statins, selective serotonin re-uptake inhibitors and antiepileptics).
Objectives To analyse the clinical characteristics and association with AD in patients with MC at a Spanish tertiary hospital.
Methods We conducted a descriptive, retrospective study of patients with MC (biopsy-confirmed diagnosis) treated in our hospital between January 1999 and December 2014. The data were obtained by reviewing their medical records.
Results A total of 97 cases were included, with a median age at diagnosis being 66 years (range: 15-88) and a female:male ratio of 2.1:1. Among the types of MC, 63% corresponded to LC, 30% to CC and 7% to overlap of both. There was a history of smoking in 23.7% of patients, intake of involved drugs in 58.8% and previous intestinal infection in 3%. The most common symptoms were diarrhoea (94.8%), nocturnal stools (13.4%), defecation urgency (7.2%), abdominal pain (44.3%), weight loss (51.5%), nausea (17.5%), vomiting (12.4%) and asthenia (16.5%). The most common laboratory abnormalities were anaemia (9.2%) and increased levels of ESR and/or CRP (29%). There was associated AD in 28.9% of cases (systemic 8, organ-specific 20). The diagnoses of systemic AD found were: polymyalgia rheumatica (3), giant cell arteritis (1), rheumatoid arthritis (2), ankylosing spondylitis (1) and undifferentiated spondyloarthritis (1). Organ-specific AD found were: autoimmune thyroid disease (12), autoimmune polyglandular syndrome type III (1), celiac disease (2), multiple sclerosis (2), autoimmune cholangitis (1), and uveitis (1). The frequency of AD was higher in the CC (41.3%) compared to LC (24.5%), but this did not present statistically significant difference between these two (p=0.1043). AD preceded the diagnosis of MC in 19 cases, were concomitant in 2 and subsequently developed in 7.
Conclusions More than a quarter of cases of MC in our series had associated AD, being more frequent the autoimmune endocrinopathies, but also the inflammatory rheumatic diseases. A higher frequency of AD was found in CC than CL, similar to that reported in other series, but without significant difference. The knowledge of this entity by the rheumatologists is important as well as the communication with the gastroenterologists for early referral of the patients with MC and suspicion of these diseases.
Disclosure of Interest None declared