Endocrine Abstracts

Fibrous dysplasia (FD) is a relatively uncommon condition presenting with combinations of focal bone abnormalities, cutaneous hyperpigmentation and endocrinopathy. It is caused by a post-zygotic mutation in a G-protein coupled receptor (GNAS1) leading to constitutive activation of several hormone signaling pathways. Severely affected patients present in childhood with extensive bone lesions+endocrine disorder e.g. premature puberty (McCune–Albright syndrome) but less severely affected individuals can present later with painful bone lesions or fracture. The use of intravenous bisphosphonates (e.g. pamidronate) has been proposed for the treatment of bone lesions to reduce pain, deformity and risk of fracture. As part of the development of a new service we retrospectively examined the safety and effectiveness of bisphosphonate treatment in patients diagnosed with FD at our orthopaedic hospital (the largest elective joint replacement centre in Europe with a major bone tumour unit). A questionnaire designed to capture both quantitative and qualitative date (number of treatments, pain scores, QOL) was distributed to adults with FD who had received IV pamidronate (n=13). Eleven patients replied. Responses were correlated with data recorded in the notes. Most patients (n=10) had FD restricted to a small number of bones. The only endocrine disorder was hypophosphataemia (n=1). The primary finding was that reported pain scores after pamidronate were significantly lower than before treatment (7.8±1.5 vs 2.9+3.0 (mean±S.D.) on scale of 1–10 with 10 worst pain; P<0.001). Given the low numbers it was impossible to assess any effect on the appearance of FD lesions or risk of complications. The commonest adverse effect was flu-like symptoms after the first dose (n=6) but one patient with FD of the sphenoid developed transient periorbital swelling and visual disturbance. Although the retrospective nature of the study and lack of a control group limit the conclusions that can be made IV pamidronate appears effective in improving symptoms in most patients with FD. Further examination of the effectiveness of bisphosphonates in FD would require a multicentre controlled trial.