Long-term radiographic follow-up after isotretinoin therapy.

We evaluated the effects of long- and short-term isotretinoin therapy on the skeletons of patients. Eight patients who were treated with isotretinoin for disorders of keratinization received frequent radiographic evaluations for 4 to 9 years. Seven patients developed multiple hyperostoses at the spine and extremities. Hyperostoses increased in size and number over the course of therapy, although relatively few sites were symptomatic. Hyperostoses typically developed first in the spine and later in the extremities, where both bilaterally symmetric and asymmetric involvement was observed. After 5 years of therapy one patient did not develop hyperostosis. In a group of nine patients who received a relatively high dose of isotretinoin in 1982 for the treatment of acne, two patients developed tiny, asymptomatic hyperostoses. One patient had hyperostoses 1 year after isotretinoin therapy, which remained unchanged 3 years later, whereas the other patient had one hyperostosis 4 years after therapy had been stopped. Although we suspect that these hyperostoses were retinoid induced, they should not be of concern for the patient needing routine isotretinoin therapy for the treatment of cystic acne.