Introduction: McCuneAlbright syndrome (MAS) is a genetic disorder characterized by constitutive activation of Gsα, resulting in excessive activity of multiple hormones. The most known clinical characteristics are the presence of polyostotic fibrous dysplasia (FD), hyperpigmented skin spots, and gonadotropin-independent precocious puberty (PP). However, other endocrine manifestations can be found like hypophosphatemic rickets due to FGF-23-induced renal phosphate wasting.
Case report: A 7-year-old girl was diagnosed with MAS at 4.9 years, with vaginal bleeding at 1.7 years, associated to large and irregular skin spots and fibrous dysplasia. This patient also has facial dysmorphisms, as saddle nose. No other endocrine manifestation was identified. Bone scintigraphy with technetium 99 showed increased uptake tracer with heterogeneous pattern in skull, ribs, hipbone and limbs, especially in facial bones. A cranium CT was performed due to migraine. Microcephaly and diffuse bone enlargement were noted, with global small tapering of bone foramens with accommodation of periencephalic spaces. She developed genu valgus, fibrous dysplasia and decreased cortical bone. As phosphate serum level was low, associated to increased renal phosphate wasting, hypophosphatemic hyperphosphaturic rickets was diagnosed. She was treated with calcium carbonate and tamoxifen and, due to bone dysmorphism, calcitriol, phosphate, and pamidronate were introduced.
Conclusion: Despite MAS is known by its most known characteristics, such as PP, FD, and skin spots, the screening for other endocrine disorders is mandatory. The presence of polyostotic fibrous dysplasia does not exclude the findings of rickets. It has been suggested that the large skin spots may alert us to overproduction of FGF-23 that could be a marker of the condition of phosphate wasting. Therefore, a special attention about the phosphate metabolism should be done in these patients.
20 - 22 Sep 2014
European Society for Paediatric Endocrinology