Collagenous gastritis: Still a mystery

Microscopic colitis is a well-defined entity comprising two histopathological subtypes: lymphocytic colitis and collagenous colitis, which may represent different stages of the same disease. Upper gastrointestinal involvement by a process sharing histological features with microscopic colitis appears to be much more uncommon, and its pathogenesis, clinical significance, and management remain poorly characterised in the literature, as it may be easily overlooked or mistaken for other entities.

We retrospectively reviewed a series of patients with collagenous gastritis diagnosed at a large tertiary hospital serving a population of over 500,000 inhabitants in the metropolitan area of Madrid, Spain. Between 2010 and 2023, only seven gastric biopsy specimens were diagnosed as collagenous gastritis, corresponding to five patients.

All patients were women, aged 21-38 years. They presented with non-specific symptoms, and endoscopy revealed only mild nodularity in one case. Random gastric biopsies established the diagnosis of collagenous gastritis. None of the patients had associated collagenous colitis, collagenous enteritis or coeliac disease. Only one patient underwent long-term follow-up with sequential biopsies, which demonstrated persistent histological changes over time while the patient remained asymptomatic.

A recent systematic review identified 101 patients with collagenous gastritis presenting with heterogenous clinical profiles and an overall favourable prognosis, even in the absence of specific treatment. It remains unclear whether collagenous gastritis represents a distinct clinicopathological entity or merely a residual histopathological finding, as there are no clear-cut clinical or endoscopic features that allow reliable suspicion of this disease.