An update in the diagnosis of coeliac disease.

Coeliac disease is increasing in prevalence, which is currently estimated at one in 100 of the population and may occur de novo in adults. The diagnosis requires a joint clinicopathological approach; the recommended first-line test is serology with immunoglobulin A (IgA) tissue transglutaminase and IgA endomysial antibodies. These serological tests show high levels of sensitivity and specificity, but biopsy is the gold standard to confirm the diagnosis. It is important that both tests are performed before the introduction of a gluten-free diet. Although the classical histopathology changes of coeliac disease with partial or total villous atrophy are well recognized, the pathology classification of coeliac disease is changing, with recognition that coeliac disease may show minimal pathology (normal architecture and an intraepithelial lymphocyte count/100 enterocytes ≥ 25). This entity is also described as lymphocytic duodenosis, and recommendation of follow-up serology testing is paramount in this condition. Follow-up of patients with coeliac disease is warranted, as normal serology does not predict mucosal recovery. Failure to heal predicts risk of progression to refractory coeliac disease and malignancies. Refractory coeliac disease occurs in 1-2% of patients and this diagnosis requires a combined clinical and histopathology approach with immunocytochemistry.