[Hip and spinal ossification enthesopathies induced by etretinate therapy in peripheral psoriatic arthritis]

The occurrence of ossifying enthesopathy during treatment with synthetic retinoids (etretinate, isotretinoin and acitretin) is a side-effect more and more frequently recorded. The authors report here a new case in a patient with a severe psoriatic arthritis. This observation is characterized by the size of ossifications on hips and lumbar spine which appeared after two years of etretinate therapy. The interest of this observation lies in the fact that ossifications occurred while the patient was treated with long-term corticotherapy. The disease for which retinoids are prescribed does not seem to influence the occurrence of those lesions and it is likely that the responsibility of these molecules is entire. Lesions are enthesitis ossification. They are frequent during these treatments (average of 70%) after an average time of 24 to 36 months for etretinate and of 10 months for isotretinoin. Lesions are asymptomatic in about 50% of the cases. After discontinuation of treatment, lesions become quiescent and does not disappear. Growth hormone or abnormalities in vitamin A metabolism could play a role in the physiopathology of lesions.