Vertebral abnormalities associated with synthetic retinoid use.

Frequent symptoms of back and neck stiffness led to a radiographic investigation of the vertebral spine in patients receiving synthetic retinoids, isotretinoin and etretinate. X-ray examination of fifty patients with various skin disorders who received retinoids for at least 2 years were compared with seventy-two age- and sex-matched untreated patients. Differences in frequencies of defined abnormalities, which included anterior spinal ligament calcification and presence of osteophyte at two or more vertebral levels in the absence of joint space narrowing, were determined for treated and untreated patients. When the entire group of treated patients was compared with the entire group of those untreated, no statistically significant differences were observed. When only patients with basal cell nevus syndrome ( BCNS ) or basal cell carcinoma (BCC) who had never received retinoid were compared with those who received isotretinoin, the frequency of the defined abnormalities was significantly higher in the treated group (P less than 0.01). This study suggests that the ingestion of isotretinoin at mean total dose of 150,060 mg for an average of 2.9 years is associated with a statistically significant increase in developing an associated ossifying diathesis in patients with BCNS or BCC, when compared with matched, untreated controls.