[Rheumatologic effects of etretinate].

The effects of chronic hypervitaminosis A and long-term isotretinoin treatment on bone include cortical hyperostosis, ligament calcification and premature epiphyseal closure. Similar effects have now been reported in patients under maintenance treatment with etretinate in high doses. Etretinate, an oral, aromatic, synthetic vitamin A derivative, is widely used in Europe for disorders of keratinization. We report the cases of two patients--one with lamellar ichthyosis, the other with pachyonychia congenita--who developed such bone diseases during treatment with etretinate over 2 and 6 years respectively. The doses ranged from 0.5 to 1 mg/kg/day. Two years after starting treatment (total dose 25 g), the patient with lamellar ichthyosis complained of mechanical pain in the lumbar region and hips. Radiography showed calcification of the extraspinal tendons and ligaments and hyperostosis of the calcaneus bone at the insertion of the plantar ligament. After six years of etretinate treatment (total dose 50 g), the patient with pachyonychia congenita presented with scoliosis and limb length discrepancy. The musculoskeletal abnormalities resembled chronic hypervitaminosis A, with such osseous changes as demineralization, thinning and increased curvature of long bones with osteopenia, and premature closure of the epiphyses. Acroosteolysis was also present. Etretinate has been implicated in the formation of spinal hyperostoses and calcification of extraspinal ligaments in patients who had taken the drug for many years. The occurrence of premature epiphyseal closure in children certainly is a consequence of therapy with relatively high doses of etretinate for six years. But premature epiphyseal closure may also result from trauma to a fragile bone.(ABSTRACT TRUNCATED AT 250 WORDS)