McCune-Albright Syndrome with Hypophosphatemic Rickets

Abstract

Fibrous dysplasia (FD) is sometimes accompanied by extraskeletal manifestations that can include any combination of cafe-au-lait macules, hyperfunctioning endocrinopathies, such as gonadotropin-independent precocious puberty, hyperthyroidism, growth hormone excess, FGF23-mediated renal phosphate wasting, and/or Cushing’s syndrome, as well as other less common features. The combination of any of these findings, with or without FD, is known as McCune-Albright syndrome (MAS). The broad spectrum of involved tissues and the unpredictable combination of findings is because of a molecular defect due to dominant activating mutations in the widely expressed signalling protein Gsα. These mutations arise sporadically, often early in development, prior to gastrulation and can distribute across many or few tissues. 1,2 We present a case of a 3½ year-old-girl who presented simultaneously with precocious puberty and hypophosphatemic rickets, along with fibrous dysplasia and cafe au lait macules.