Endocrine Abstracts

Introduction: McCune-Albright syndrome (MAS) consists of at least two of the following three conditions: polyostotic fibrous dysplasia (PFD), café-au-lait skin pigmentation and autonomous endocrine hyperfunction. The most common form of autonomous endocrine hyperfunction is precocious puberty, but other syndromes may be present, including acromegaly, hyperthyroidism, and Cushing syndrome. Acromegaly is seen in approximately 20% of patients with MAS. Treatment options are medical, surgical and radiotherapy, but surgical treatment is difficult because of fibrous thickening of the skull floor.

Case report: A 33-year-old man, black race, natural of Guinea-Bissau, living in Portugal since the age of 30. Referred to Rheumatology outpatient clinic in July of 2016 with the history of deformity of the lower limbs, hip pain in the right and staggering gait, since de age of 14, and worsening progressively. No pathological history, without reference to precocious puberty and no usual medication. No family history. After physical examination and radiography exams made the diagnosis of PFD. Requested the collaboration of Endocrinology by analytical alterations: GH 12 ug/L (<1) and IGF1 428 ng/ml (115–307). Placed the hypothesis of MAC with acromegaly. Physical exam: stature 158 cm, weight 68 Kg (BMI 27.2 Kg/m²), no endocrinopathy stigmas. Imaging study: pituitary MR ‘fibrous dysplasia polyostotic facial skull with extensive facial mass changes. Presence of left lateral pituitary adenoma with 8 mm height’; GH at the OGTT 11 ng/mL. Acromegaly was diagnosed. Genetic test shows somatic mutation in the GNAS1 gene – variant c.601C that confirms the MAS diagnostic with acromegaly. Due to widespread bone involvement in the cranium and facial skull surgical treatment was not planned. Octreotide LAR therapy was started with 20 mg every 4 weeks, and after 4 months GH decreased to 5.1 ng/mL and IGF1 to 253 ng/mL. The patient is still under monitoring by our clinic, with no symptoms of disease having relapsed.

Conclusion: Medical treatment is considered the first line in patients with acromegaly associated with the McCune-Albright syndrome. Somatostatin analogues improve GH/IGF1 levels in most patients although remission has been only achieved in 30% of patients. The malignancy of fibrous dysplasia is very low and occurs in a small percentage of patients, possibly due to irradiation of bone lesions. Pituitary therapeutic irradiation should therefore be avoided in these patients and diagnostic irradiation should be kept to a minimum. The follow-up of comorbidities associated with acromegaly in the McCune-Albright syndrome is similar to that of patients with classical acromegaly.