Generalized pustular psoriasis complicated by acute respiratory distress syndrome

Psoriasis has a chronic and relatively benign course. However, severe complications are possible. One rare complication is acute interstitial pneumonitis. This entity should be suspected when a patient presents with dyspnoea and high fever. Knowledge of this pathology is crucial, for although it is essential to rule out aetiologies requiring specific management such as microbial infection or drug-related syndromes, diagnosis should not be delayed as its severe clinical course is improved by corticosteroids. We report two patients with an acute respiratory distress syndrome arising during the course of pustular psoriasis. Repeated bacteriological testing in lungs and blood remained negative. In both cases lung involvement was severe, requiring artificial ventilation. Dramatic clinical resolution was obtained by using corticosteroids. Besides infectious causes and drug hypersensitivity to methotrexate or acitretin, acute respiratory distress syndrome, sometimes due to a pulmonary capillary leak syndrome, is a rare cause of pneumonitis in the course of psoriasis, and may be fatal. Its pathogenesis is unknown. However, animal models suggest a role for T-helper (Th) 1 lymphocytes, known to be activated in psoriasis, and a role for tumour necrosis factor-alpha, a major Th1 cytokine, in alveolar damage.