McCune-Albright syndrome (MAS) is a rare disorder that develops from an activating mutation in the Gs gene. It is characterized by an association with Polyostotic fibrous dysplasia, and precocious puberty, Caf-au-lait pigmentation, and other endocrinopathies that result from the hyperactivity of a variety of endocrine glands. Recently we encountered a patient with MAS with fibrous dysplasia, skin pigmentation, acromegaly, hyperprolactinemia and a thyroid nodule. A 23-year-old male presented for an evaluation of a change in his facial structures. Fibrous dysplasia was diagnosed by a bone biopsy and radiographic studies. The GH level increased paradoxically after an oral glucose load. The plasma prolactin, IGF-1 and alkaline phosphatase were high. Thyroid ultrasonography revealed multiple nodules. The brain MRI demonstrated a mass in the left pituitary gland. Genetic analysis identified a change from Arg (CGT) at codon 201 to Cys (TGT).
Thyroid Diseases/etiology/genetics ; Puberty, Precocious/etiology/genetics ; Mutation ; Male ; Hyperprolactinemia/etiology/genetics ; Humans ; GTP-Binding Protein alpha Subunits, Gs/*genetics ; Fibrous Dysplasia, Polyostotic/*diagnosis/genetics/pathology ; Cafe-au-Lait Spots/etiology/genetics ; Adult ; Acromegaly/*diagnosis/etiology

The aim of this study was to investigate the relationship between somatostatinergic tone (SST) and the size of growth hormone (GH)-producing pituitary tumors. GH levels of 29 patients with newly diagnosed acromegaly were measured using a 75-gram oral glucose tolerance test (OGTT), an insulin tolerance test (ITT), and an octreotide suppression test (OST). Differences between GH levels during the ITT and the OGTT (DeltaGH(IO)), and between the OGTT and the OST at the same time point (DeltaGH(OS)) were compared according to the size of the tumor and the response pattern to the OST. DeltaGH(IO) of macroadenomas (n=22) was non-significantly higher than those of microadenomas while DeltaGH(OS) of macroadenomas were significantly higher than those of microadenomas. According to further analyses of macroadenomas based on the response pattern to the OST, GH levels during the ITT were significantly higher in non-responders. DeltaGH(OS) showed near-significant differences between responders and non-responders. In conclusion, as the size of the pituitary tumor increases, the effect of glucose on SST appears to be attenuated. Macroadenomas that are non-responders to the OST possess a portion of GH secretion exceeding the range of regulation by SST.
Acromegaly/*diagnosis/*pathology ; Adenoma/drug therapy/*pathology ; Adult ; Aged ; Antineoplastic Agents, Hormonal/therapeutic use ; Female ; Glucose Tolerance Test ; Human Growth Hormone/*blood/secretion ; Humans ; Insulin/blood ; Insulin-Like Growth Factor I/analysis ; Male ; Middle Aged ; Octreotide/therapeutic use ; Pituitary Neoplasms/drug therapy/*pathology