Bone-scintigraphic examinations in patients treated with retinoids: a prospective study

Hypercalcemia and osteoblastic lesions induced by 13-Cis-retinoic acid mimicking relapsed neuroblastoma

A 6-year-old male diagnosed with extensive neuroblastoma was treated with chemotherapy, surgery, autotransplantation, and radiotherapy. He was then enrolled on a study to assess the monoclonal antibody Ch14.18 (anti-GD2) with 13 cis-retinoic acid. 13-cis-retinoic acid therapy caused severe bone pain and hypercalcemia. Bone scans showed multiple osteoblastic lesions suggesting recurrent disease however MIBG scans were negative. Serum markers of bone turnover were increased and the patient required pamidronate therapy to treat persistent hypercalcemia. Retinoic acid toxicity needs to be considered in the differential of painful osteoblastic lesions and/or hypercalcemia. MIBG scans can assist in differentiating from recurrent disease.

Lack of significant skeletal changes after long-term, low-dose retinoid therapy: case report and review of the literature

BACKGROUND

Long-term systemic retinoid therapy has been associated with skeletal side effects. There have been reports of diffuse idiopathic skeletal hyperostosis (DISH) syndrome, calcification of ligaments, and osteoporosis, as well as premature fusion of epiphyses and modeling abnormalities of long bones, occurring in patients on chronic high-dose isotretinoin, etretinate, and acitretin therapy. Low-dose acitretin has been used for many years as monotherapy or in combination with other systemic therapies for psoriasis. Evidence to date suggests that the frequency of symptomatic bony effects is quite low in these patients.

OBJECTIVE

To present the radiologic findings of a patient on long-term, low-dose acitretin and etretinate and to review the literature on the radiologic evidence of skeletal side effects during retinoid therapy.

METHODS

Case report and literature search.

RESULTS

A patient on low-dose acitretin had no significant radiologic abnormalities associated with retinoid use after 9 years of treatment. A review of the literature revealed conflicting reports on the incidence of radiologic abnormalities in patients on retinoid treatment.

CONCLUSION

The evidence to date does not substantiate a clear link between radiologic skeletal abnormalities and long-term, low-dose acitretin or etretinate therapy.

Extraspinal enthesopathy caused by isotretinoin therapy

OBJECTIVE

To discuss a case of diffuse peripheral enthesopathy in a patient previously treated with long-term isotretinoin (Accutane) for severe acne.

CLINICAL FEATURES

A 47-year old man with 1 month history of moderate neck and right upper extremity pain, with hypoesthesia of the right second and third fingers. Palpable bony prominences around multiple superficial joints were noted on physical examination, raising the initial question of osteochondromatosis. Multiple active acne pustules were noted. A limited skeletal survey demonstrated diffuse peripheral enthesophyte formation and hyperostoses, resembling those of diffuse idiopathic skeletal hyperostosis, but without accompanying spinal changes. A history of long-term Accutane therapy was then elicited.

INTERVENTION AND OUTCOME

The enthesopathy was believed to represent an asymptomatic, longstanding, iatrogenically induced abnormality. No specific therapy or follow-up was indicated. The patient had discontinued use of Accutane years ago. Cervical symptoms improved with four sessions of cervical traction and nonsteroidal anti-inflammatory medications, but upper extremity symptoms were refractory.

CONCLUSION

Accutane-induced enthesopathy should be considered in individuals with correlating radiologic and clinical features and history of retinoic acid therapy for acne. This should be a diagnosis by exclusion, after eliminating other potential causes of peripheral enthesopathy, particularly diffuse idiopathic skeletal hyperostosis, seronegative spondylarthropathy, and fluorosis.

13-cis-retinoic acid and bone density

BACKGROUND

13-Cis-retinoic acid has an influence on bone in patients on long-term treatment as well as on short-term treatment. The presence of skeletal abnormalities after the treatment was established by roentgenologic and scintigraphic examinations. We wanted to know whether a 6-month course of low-dose 13-cis-retinoic acid has a clinically important influence on bone density in men with severe acne.

METHODS

We examined 15 men with severe acne before and after treatment with 13-cis-retinoic acid by dual-photon absorptiometry of the lumbar spine.

RESULTS

The mean increase in bone density was 3.0% (95% confidence interval 1.3-4.5), which is normal for the period from puberty to late twenties. Bone density increased in 13 of our 15 patients.

CONCLUSIONS

As shown by this highly sensitive modern densitometric method, 13-cis-retinoic acid has no clinically important influence on bone density in male patients with severe acne.

Long-term safety of retinoid therapy

The concern about long-term toxicity of oral synthetic retinoids has developed because many patients, especially those with genodermatoses, require lifelong therapy. Several organ systems are at risk, especially the hepatic, skeletal, and cardiovascular systems. Although acute hepatotoxicity is a rare side effect of etretinate and acitretin therapy, prospective studies have not demonstrated chronic liver toxicity. The frequency of bone changes induced by retinoids is difficult to estimate, because this adverse effect is usually asymptomatic and requires x-ray or scintigraphic examination for detection. Atherosclerosis develops in many patients who receive long-term retinoid therapy, but the extent to which the process is aggravated by drug-induced hyperlipidemia is not known. Many patients have now been treated with either etretinate or isotretinoin continuously for as many as 15 years and have not developed any signs of severe chronic toxicity. However, continued intense surveillance is recommended for patients expected to require lifelong therapy.

Bone changes and their significance in children with ichthyosis on long-term etretinate therapy

Anxiety about the use of etretinate in children has been provoked by several reports describing skeletal abnormalities during long-term therapy. However, we have observed no evidence of skeletal toxicity in 42 children treated over an 11-year period. Radiological screening before and during treatment has failed to reveal abnormalities that would influence our decision to commence or to continue etretinate administration. We recommend that children who are to be treated with etretinate should have a baseline selective skeletal survey, with follow-up radiology restricted to those with pretreatment radiological abnormalities and those who develop musculo-skeletal symptoms. In addition we advise that dosage should not exceed 1 mg/kg/day. If these guidelines are followed, we believe that long-term therapy with etretinate can be given to children, with an acceptable margin of safety.

Rheumatological symptoms due to retinoids

Isotretinoin and etretinate are synthetic derivatives of vitamin A widely used in the treatment of dermatological diseases, mainly those affecting keratinization. They have numerous side-effects, among which the rheumatic symptoms are not the most common or the most severe. The main skeletal adverse reaction of retinoids is hyperostosis. It mainly occurs with protracted treatments and high dosages, and its incidence may exceed 80% after a few years of administration. Hyperostosis is axial, located in the cervical and thoracic spine, and may be responsible for limitation of movement; in the appendicular bone, enthesopathies occur at the foot, pelvis, hip, and less commonly the shoulder and elbow. They are usually mild and asymptomatic. The radiological appearance is very similar to diffuse idiopathic skeletal hyperostosis. Isotretinoin tends to be responsible for axial involvement, etretinate for peripheral locations. The other skeletal side-effects are uncommon and include periosteal proliferation, calcification of the interosseous membrane of the forearm and diffuse radiological bone hyperlucency. In children, premature epiphyseal closure is very rare. About 20% of patients complain of musculoskeletal pain and arthralgias. A few cases of true arthritis have been reported. Retinoids may be responsible for muscular damage and an abnormality of muscular tone resembling the stiff-man syndrome. Some cases of necrotizing vasculitis and three cases of Wegener's granulomatosis have been observed in patients treated with retinoids. Except for these latter arguable cases, rheumatoid syndromes due to retinoids are rather benign, and should not be an obstacle to the future development of their therapeutic utilization.

Risk: benefit ratio in the treatment of psoriasis with systemic retinoids

This is a review of the efficacy of etretinate/acitretin in the treatment of psoriasis and of the currently reported side-effects. The data indicate that retinoids bring significant improvement (if not total clearing) with frequent low-morbidity but rarely serious side-effects. The most serious side-effect of etretinate/acitretin is teratogenicity.