Aphthous Stomatitis in a Man with Psoriatic Arthritis

A 57-year-old man was admitted to the Department of Internal Medicine for a painful aphthous stomatitis, which had been present for 2 weeks and had not resolved under antibiotic treatment (amoxicillin-clavulanic acid). He had a medical history of psoriatic arthritis, successfully treated for 5 years with adalimumab, an anti-tumor necrosis factor agent. A loss of effect had been suspected because of severe fatigue, and adalimumab had been replaced by secukinumab, an interleukin (IL)-17A inhibitor, 6 months before admission. He was also receiving clopidogrel and flecainide for atrial fibrillation, and oral potassium for chronic hypokalemia. He had a family history (an uncle and a cousin) of Crohn’s disease.

He reported fever, weight loss (15 kg in the last 6 months), and chronic abdominal symptoms (severe abdominal pain relieved by diarrhea) for several years. An ileocolonoscopy performed 5 years previously had been normal.

Aphthous ulcers on the uvula, tongue, and gums (Figure 1) were revealed by oral examination. The clinical examination was otherwise unremarkable. Blood tests found elevated levels of acute phase reactants (ie, C-reactive protein = 180 mg/L) and no vitamin, zinc, or iron deficiency. Two herpes simplex virus polymerase chain reaction assays in the aphthous lesions were negative, as were serological tests for the human immunodeficiency virus, syphilis, and Mycoplasma pneumonia. Fecal calprotectin was elevated (1104 μg/g, normal levels: less than 50 µg/g). Ileocolonoscopy and multiple bowel biopsies were unremarkable, but magnetic resonance imaging of the small intestine found segmental ileitis (Figure 2).