Skeletal toxicity with isotretinoin therapy: a clinico-radiological evaluation

Skeletal toxicity is known to occur with high doses of isotretinoin (greater than 2 mg/kg/day). We have attempted to evaluate the clinical significance and document the extent of musculoskeletal toxicity associated with a relatively low dose of isotretinoin (0.5 mg/kg/day) used in the treatment of severe acne. Radiographs of 120 patients were examined. Twelve per cent showed minor changes (four patients had spinal hyperostoses and 10 had calcaneal hyperostoses). None of the musculoskeletal changes we observed was clinically significant. Comparison with matched control X-rays showed 8% of the controls to have similar non-significant changes. Follow-up of 11 of the patients with abnormal X-rays showed minor deterioration in one patient, no change in four and improvement in six. Thus, doses of 0.5 mg/kg/day isotretinoin in such patients did not produce any significant long-term musculoskeletal changes. With increasing use of this beneficial drug in acne, radiologists and dermatologists should be aware of its skeletal toxicity.