Development of Crohn disease in a patient on etanercept for psoriasis

Conflicts of interest: none declared. Sir, A 68‐year‐old man had a 30‐year history of psoriasis and psoriatic arthritis (PsA). His psoriasis was difficult to control. He was intolerant of psoralen plus ultraviolet A radiation, he developed abnormal liver function on methotrexate, etretinate caused calcification of the spinous ligament and ciclosporin resulted in renal impairment. Infliximab was introduced at 5 mg kg−1 with an excellent response but at 4 months he developed severe neutropenia which required treatment with granulocyte colony stimulating factor. He developed a high antinuclear antibody titre (1 : 800) after 10 months and his treatment was changed to etanercept (25 mg twice weekly). This was effective in controlling both his psoriasis and PsA. Six months later, he complained of abdominal pain with 10 episodes of severe diarrhoea per day. This had a significant impact on his daily life and he lost 8 kg weight in 3 months. A colonoscopy revealed a decreased vascular pattern with easy contact bleeding and inflammation. Histology showed acute and chronic inflammation with cryptitis, crypt abscesses and granulomas. The changes were consistent with Crohn disease (CD). When there was no improvement with mesalazine, it was discontinued after 3 months. Etanercept was changed to adalimumab (40 mg fortnightly) and within 3 months his intestinal symptoms improved significantly. Six months later, his psoriasis, PsA and CD are well controlled on adalimumab.