Residual Effect of bisphosphonates: spectacular improvement after discontinous intravenous pamidronate in fibrous dysplasia

PARISI MS; MAUTALEN C; OLIVERI B

Phyladelphia USA

Congreso; 28th Meeting American Society for bone and mineral research; 2006

American Society for bone and mineral research

Residual Effect of Bisphoshponates: Spectacular Improvement after Discontinuous Intravenous Pamidronate in Fibrous Dysplasia M.S. Parisi, B. Oliveri, C. Mautalen Sección Osteopatías Médicas, Hospital de Clínicas, Universidad de Buenos Aires, Argentina In the past 10 years bisphosphonates have become one of the choice drugs to treat Fibrous dysplasia (FD) of bone. Bisphosphonates have been reported to reduce bone pain and markers of bone turnover in FD patients and to improve BMD and radiological images in FD areas. We present a 6 year follow-up of a patient treated with iv pamidronate, in which the effect of bisphosphonate persisted even after treatment was discontinued. In December 1999, a 24-year-old woman presented a right humerus fracture. FD diagnosis was based on characteristic radiological images. We observed multiple osteolytic lesions, with reduction of cortical thickness all along the affected humerus. Radioisotope bone scan did not reveal increased uptake in other skeletal areas. Baseline biochemical determinations showed increased values of bone turnover markers, and the patient reported continuous pain. BMD was determined on the total skeleton scan. Using the region of interest program, BMD of the FD right humerus was compared to the counterlateral healthy side, which showed a 17% reduction. Pamidronate was administered intravenously four times over a period of 2 years (60mg/d for 3 days every 6 months). Thereafter, only one cycle of 90mg was indicated in the fourth year of follow-up, due to reappearance of bone pain. Total dose of pamidronate was 810mg. A complete clinical, biochemical, radiological and densitometric assessment was done at regular intervals. Bone pain gradually decreased during the first year but did not disappear, and intermittent periods of pain were reported. bone turnover markers reached normal values after the first pamidronate cycle and have remained normal until now. BMD of the FD right humerus increased gradually, and after 6 years a 20% increase in the affected bone compared to 1.5% in the counterlateral healthy side was observed. difference between the two humerus decreased from 17 to 2%. Radiologically, a partial refilling in a small osteolytic area started to appear after the second year of treatment. however, 6 years since initial treatment and 2 years after the last 90mg cycle, we observed a spectacular radiological improvement, with refilling of almost all the osteolytic areas and increased cortical thickness in a substantial part of the affected humerus. In this patient the effect of pamidronate persisted in FD areas during a long period of time, even after discontinuing therapy. This original observation could be useful for planning treatment strategies for specific FD patients. It remains to be elucidated which molecular mechanism is involved in the effect of pamidronate on FD bone.