Acromegaly in a patient with normal pituitary gland and somatotropic adenoma located in the sphenoid sinus

Abstract

Ectopic acromegaly is a very rare clinical entity occurring in less than 1% of acromegalic patients. In most cases it is caused by GHRH or rarely GH–secreting neoplasms. Even rarer are ectopic pituitary adenomas located in the sphenoid sinus or nasopharynx that originate from pituitary remnants in the craniopharyngeal duct. This dissertation presents the difficulties in visualizing GH-secreting adenoma located in the sphenoid sinus. A 55-year-old man had somatic features of acromegaly for several years. MRI imaging revealed a slightly asymmetric pituitary gland (14 ¥ 4 mm) without focal lesions. Simultaneously, a spherical mass, 10 mm in diameter, corresponding with ectopic microadenoma was demonstrated on the upper wall of the sphenoid sinus. The serum GH level was 4.3 mg/l, IGF-1 = 615 mg/l, and a lack of GH suppression with oral glucose was proven. After preliminary treatment with a long-acting somatostatin analogue, transsphenoidal pituitary tumour removal was performed. Histopathological, electron microscopical and immunohistochemical analysis revealed densely granulated somatotropic pituitary adenoma: GH(+), PRL(-), ACTH(-), TSH(-), FSH(-), LH(-), MIB1 < 1%, SSTR3(+) and SSTR5(+). Post-surgical evaluation showed normal pituitary MRI scans, GH and IGF-1 levels 0.18 μg/l and 140 mg/l, respectively, as well as normal GH suppression with oral glucose. The careful analysis of possible pituitary embryonic malformations points out their significance for proper localization of extrapituitary adenomas.