Patients with psoriatic arthritis have an increased number of lymphocytes in the duodenal mucosa in comparison with patients with psoriasis vulgaris.

Objective: To determine if there is evidence of inflammation in the duodenal mucosa in patients with psoriatic arthritis (PsA) and to compare the results with those in patients with psoriasis vulgaris (PsV).

Methods: Nineteen consecutive patients with PsA underwent gastroduodenoscopy, and biopsy specimens were taken from the duodenal and gastric mucosa. In addition to routine processing, the duodenal mucosal specimens were stained for CD3+, CD8+ and CD4+ T lymphocytes, tryptase-positive mast cells, and EG2-positive eosinophil granulocytes. The results were compared with those in duodenal mucosal specimens from patients with PsV and patients with irritable bowel syndrome.

Results: Compared with PsV patients (without antibodies against gliadin), patients with PsA had a highly significant increase in intraepithelial CD3+ and CD8+ lymphocytes and also in CD4+ lymphocytes in the lamina propria in the villi. The lymphocyte increase was not related to presence of IgA antibodies against gliadin, endomysium, or transglutaminase, or to concomitant gastritis. Patients with PsA and PsV showed a pronounced increase in mast cells and eosinophil granulocytes.

Conclusion: The increased lymphocyte infiltration in the duodenal mucosa in PsA, but not in PsV, might indicate different pathogenetic mechanisms in these psoriasis variants.