Introduction: McCune–Albright syndrome (MAS) is a rare, sporadic mosaic disorder caused by postzygotic activating mutations of the GNAS gene. It is classically characterized by a triad of polyostotic fibrous dysplasia, café-au-lait skin macules, and hyperfunctioning endocrinopathies. Growth hormone (GH) excess represents a particularly challenging manifestation and is most often associated with pituitary adenomas or somatolactotroph hyperplasia. However, atypical presentations with GH excess in the absence of radiologically detectable pituitary lesions have been reported. Case presentation: We report the case of a 43-year-old male referred for progressive craniofacial deformity and excessive height. Clinical evaluation revealed features consistent with GH excess, including gigantism, frontal bossing, prognathism, and progressive respiratory and neurological complications. Imaging demonstrated extensive polyostotic fibrous dysplasia involving the craniofacial bones, thoracic cage, and spine, resulting in severe skeletal deformities and multisystem complications. Biochemical assessment confirmed GH excess with elevated insulin-like growth factor 1 levels and failure of GH suppression during an oral glucose tolerance test. Notably, pituitary magnetic resonance imaging was completely normal, with no evidence of adenoma or hyperplasia. Additional endocrine evaluation revealed hypogonadotropic hypogonadism and structural thyroid abnormalities without functional hyperthyroidism. Based on the constellation of clinical, biochemical, and imaging findings, a diagnosis of atypical McCune–Albright syndrome was established. The patient was managed medically with a long-acting somatostatin analog and multidisciplinary follow-up. Conclusion: This case highlights the marked phenotypic heterogeneity of McCune–Albright syndrome and underscores that growth hormone–mediated gigantism may occur despite a normal pituitary MRI. Recognition of such atypical presentations is crucial to avoid diagnostic delay and to guide appropriate management. A multidisciplinary approach remains essential for optimizing outcomes in patients with complex skeletal and endocrine involvement