Endocrine Abstracts

Fibrous dysplasia (FD) is a rare bone disease which usually presents to Endocrinologists as part of McCune albright syndrome or as precocious puberty. A variety of other co-morbidities have been described for FD including renal phophate wasting secondary to an excess of FGF23; abnormal thryoid and growth hormone production and abnormal cortisol production. A large number of children are referred to our Regional Sarcoma Service with lytic bony lesions, many of which are subsequently diagnosed as FD. There is currently no screening programme in place for children with this diagnosis, as is recommended by the FD Foundation. We therefore audited all patients diagnosed with FD since 2009. Of the over 1100 patients suspected to have FD, we were able to conclusively arrive at the diagnosis in 74 patients, 43 Males and 31 females; 19/74 (25%) had polyostotic disease and 55/74 (75%) had monostotic FD. Only 3 polyostotic patients had extra skeletal signs leading to a diagnosis of McCune Albright Syndrome. 3 other patients (2 polyostotic, one monostotic)patients had a clinical presentation of hypophosphataemic rickets. No other abnormalities had been noted. Using the FD Foundation recommendations, patients were screened by Whole Body MRI(WBMRI). 20/55 monostotic and 12/19 polyostic patients were screened with 1/20 and 6/12 patients, respectively, diagnosed with ‘additional’ lesions. None of the additional lesions found, in either group, has resulted in a change to planned management but has changed advice on ongoing surveillance and physical activity. 38/74 patients have thus far undergone blood testing. 4/38 (11%) were found to have hypophosphateamia that required treatment. 2/15(20%) were in patients with polyostotic disease and 2/23(8%) were in patients with monostotic disease. No one had an endocrinopathy found on screening.

Conclusion: Although patients with FD can have co-morbidities, the prevalence reported in the literature (up to 40%) is not reflected in our prospective screening programme. Hypophosphataemia occurs in a significant proportion (11%) of all FD patients, polyostotic and monostotic. Therefore, testing for phosphate wasting is worthwhile, but screening for endocrinopathy and other skeletal lesions by routine WBMRI, especially in monostotic FD, is of questionable value.