[Ustekinumab-induced eosinophilic pneumonia during the course of ustekinumab therapy for plaque psoriasis].

BACKGROUND: Ustekinumab (Stelara(®)) is efficacious in severe cutaneous psoriasis. Numerous adverse effects have been reported but treatment withdrawal is rarely required. The present case concerns eosinophilic pneumonia treated with ustekinumab.

PATIENT AND METHODS: A 71-year-old male patient presented severe plaque psoriasis with an indication for biotherapy. Pre-treatment investigations showed a highly positive interferon gamma test without any anomalies in the CT chest scan. The patient was treated with anti-tuberculosis agents and ustekinumab was then introduced. Seven months later, the patient presented a cough resistant to antibiotics. A CT scan showed frosted-glass-like shadows and mediastinal lymphadenopathy. The bronchoalveolar lavage fluid contained 800elements/mm(3), of which 34% eosinophils. There were 1480G/L eosinophils in peripheral blood. There was nothing evocative of infectious or tumoral causes, and a diagnosis of eosinophilic pneumonia was made. Ustekinumab was stopped and 10weeks later, the patient's condition worsened; after further examination, systemic corticosteroids were given, beginning with prednisone 1mg/kg. Seven months later, the patient was symptom-free, without eosinophilia, and his chest scan was normal. The corticosteroids were stopped.

DISCUSSION: Eosinophilic pneumonia includes various disorders characterized by eosinophilic infiltration of lung tissue, with or without the presence of eosinophils in peripheral blood. Eosinophilic pneumonia can be caused by many different drugs. Diagnosis is difficult because clinical and radiological abnormalities may develop at different times after treatment initiation and they are non-specific. A favourable outcome may occur spontaneously on treatment withdrawal or a short course of corticosteroid therapy may be needed. A case of eosinophilic pneumonia under ustekinumab has already been reported, supporting the causal involvement of this drug in our patient. Eosinophils in peripheral blood have also been reported with anti-TNF-alpha. In conclusion, where a patient on biologic treatment for psoriasis presents persistent cough, once infectious disease has been ruled out, eosinophilic pneumonia should be considered.