Endocrine Abstracts

Case history: A 32 year old male diagnosed with McCune-Albright syndrome aged 18, presented with a painful left knee and difficulty in walking, limiting his usual activities. He was diagnosed with Acromegaly (IGF-1 451 ng/ml, mean GH 2.71 ug/L) aged 26 years and had multiple sites of fibrous dysplasia, causing bone pain. On examination he had tall stature and features of acromegaly with normal visual fields and palpable masses behind his left knee and upper thigh.

Investigations: ALP 657 u/l, ALT 42 u/l, bilirubin 31 umol/l, cCa 2.3 mmol/l, PO₄ 0.77 mmol/l, vitamin D 69 nmol/l, FT4 15.5 pmol/l, TSH 1.95 mu/l, IGF-1 365 mcg/l (82.5–240.4 mcg/l), mean GH 2.078 ug/l, serum procollagen type 1 amino terminal peptide (P1NP) 1158 ug/L (ref range 20–76), FGF23 160 RU/mL (ref range <100). MRI head demonstrated a normal size pituitary gland, without an obvious focal lesion, but with extensive fibrous dysplasia of the skull vault and facial bones. A whole body bone can confirmed diffuse intense tracer uptake throughout the skeleton, which showed stability in fibrous dysplasia from a scan 3 years previously. MRI demonstrated polyostotic fibrous dysplasia and multiple lobulated intramuscular soft tissue masses, with heterogeneous enhancement, the largest of which measured 6×9×10 cm.

Treatment: Pituitary surgery was relatively contraindicated due to the extensive facial and skull bone disease making access difficult. He was therefore treated with monthly Sandostatin injections, but was not very compliant with this treatment, due to gastrointestinal side effects. He received bisphosphate infusions for his bone disease.

Discussion: McCune-Albright syndrome is a rare condition that remains difficult to diagnose and manage, due to the multiple endocrine and bone complications. There is a rare association between McCune Albright syndrome and multiple myxomas known as Mazabraud syndrome. The first case was described in 1967, but very few cases have been reported in the literature. It is more common in women and tends to affect the larger lower limb muscle groups. Its occurrence in men is extremely rare, and myxomas tend to occur before the onset of fibrous dysplasia. There is an association between Mazabraud syndrome and an increased risk of sarcoma in the underlying bone, although the myxomas themselves do not seem to have an inherent malignancy risk. Use of new biochemical tests confirmed poor compliance with medications and high bone turnover. We will discuss the difficulties and management options posed by this case.