A difficult diagnosis of coeliac disease: Repeat duodenal histology increases diagnostic yield in patients with concomitant causes of villous atrophy.

Villous atrophy in absence of coeliac disease (CD)-specific antibodies represents a diagnostic dilemma. We report a case of a woman with anaemia, weight loss and diarrhoea with an initial diagnosis of seronegative CD and a histological documented villous atrophy who did not improve on gluten-free diet due to the concomitant presence of common variable immunodeficiency (CVID) and Giardia lamblia infection. This case report confirms that CD diagnosis in CVID patients is difficult; the combination of anti-endomysial antibodies (EmA-IgA), anti-tissue transglutaminase antibodies (tTG-IgAb) antibodies and total IgA is obligatory in basic diagnostic of CD but in CVID are negative. Furthermore, the typical histological aspects of the intestinal mucosa in CVID (absence of plasma cells and switch to the IgD immunoglobulins), cannot rule out a concomitant CD diagnosis. HLA typing in this setting has a low positive predictive value but should be considered. Histological response to a gluten-free diet on repeat biopsy and the concomitant treatment of other causes of villous atrophy leads to a definite diagnosis of CD.