METHOTREXATE OSTEOPATHY IN LONG-TERM, LOW-DOSE METHOTREXATE TREATMENTFOR PSORIASIS AND RHEUMATOID-ARTHRITIS

Background: In dermatology and rheumatology, methotrexate is frequentl y prescribed in low dosages per week; in oncology, high dosages per we ek are prescribed. Methotrexate osteopathy was first reported in child ren with leukemia treated with high doses of methotrexate. In animal s tudies, low doses of methotrexate proved to have an adverse effect on bone metabolism, especially on osteoblast activity. Observations: Meth otrexate osteopathy is a relatively unknown complication of low-dose m ethotrexate treatment. We describe three patients treated with low-dos e oral methotrexate in whom signs and symptoms were present that were similar to those found in children treated with high doses of methotre xate. All three patients had a triad of severe pain localized in the d istal tibiae, osteoporosis, and compression fractures of the distal ti bia, which could be identified with radiographs, technetium Tc 99m sca nning, and magnetic resonance imaging.Conclusions: Methotrexate osteop athy can occur in patients treated with low doses of methotrexate, eve n over a short period of time. As pain is localized in the distal tibi a, it is easily misdiagnosed as psoriatic arthritis of the ankle, but the diagnosis can be correctly made by careful investigation and use o f imaging techniques. The only therapy is withdrawal of methotrexate. It is important that more physicians become aware of this side effect of methotrexate therapy, which can occur along with arthritic symptoms .