ESPE Abstracts

Introduction: McCune-Albright syndrome (MAS) is a rare sporadic condition defined by the classic triad of fibrous dysplasia of bone, café au lait skin macules, and hyperfunctioning endocrinopathies. The molecular basis of MAS has been ascribed to the post-zygotic somatic gain-of-function mutations in the GNAS gene, which encodes the alpha subunit of G proteins, leading to constitutive activation of several G Protein-Coupled Receptors (GPCRs). Our aimis to report on the very severe evolutionary profile of multiostotic bone dysplasia.

Observations: We report the cases of two boys; S.D aged 08 years and O.M.Dj aged 14 years presenting McCune- Albright syndrome, the common clinical signs were essentially the triad made of café au lait skin macules, particularly broad with irregular limits sitting especially on the level of the trunk, the dysplasia of bone with like most severe lesions on the level of the superior extremity of femurs and the skull, and the precocious puberty which occurred at the age of 08 years in both. The very symptomatic hyperthyroidism set in early at the age of two in the young boy, followed by hypophoshataemia at the age of four. The treatment prescribed for both boys was based on analgesics, zoledronic acid one infusion every six months for bone dysplasia, and GnRH analogue for precocious puberty with activation of the gonadotropic axis in one case. The most disabling course was that of bone dysplasia responsible for recurrent fractures, genu varum and coxa vara bone deformities, and very significant limb inequality. The investigative work-up did not reveal any new endocrine disorders or other systemic disorders.

Discussion: McCune-Albright syndrome is a rare disease with variable clinical expression, the clinical diagnosis was easily evoked in our patients by the characteristic triad, peripheral precocious puberty considered exceptional in males was present in our patients with the appearance of endocrinopathies during follow-up represented by hyperthyroidism and hypophosphatemia well controlled with treatment, the difficulties in managing our patients are linked to the limited efficacy of Zoledronic acid on progressive bone dysplasia, with multiostotic lesions which caused bone deformities responsible for limb inequality and walking difficulties, and recurrent fractures which affected the quality of life of both patients.

Conclusion: McCune-Albright syndrome is a progressive disease responsible for multiple bone, endocrine and developmental complications, requiring regular monitoring by a multidisciplinary team in order to detect new disorders and provide early treatment.