title: Acromegaly associated with a granular cell tumor of the neurohypophysis: a clinical and histological study. Case report.
abstract: Acromegaly is usually caused by a growth hormone (GH)-secreting pituitary adenoma, and hypersecretion of GH-releasing hormone (GHRH) from a hypothalamic or neuroendocrine tumor accounts for other cases. The authors report on the unusual association of acromegaly with a granular cell tumor of the neurohypophysis. A 42-year-old woman with a 10-year history of acral enlargement, headache, and menstrual abnormalities was referred to our department for a suspected GH-secreting pituitary adenoma. The patient's basal GH levels were mildly elevated at 4.8 microg/L, were not suppressed in response to an oral glucose tolerance test, and increased paradoxically after administration of thyrotropin-releasing hormone. The patient's insulin-like growth factor-1 (IGF-1) level was elevated at 462 microg/L, whereas a magnetic resonance image of the sella turcica revealed an intra- and suprasellar lesion that was compatible with a diagnosis of pituitary adenoma. A transsphenoidal approach to remove the lesion, which was mainly suprasellar, was successful during a second operative attempt, resulting in the clinical and biochemical regression of the patient's acromegaly. Four months postoperatively, the patient's basal GH level was 0.9 microg/L and her IGF-1 level was 140 microg/L. Histological analysis of the operative specimen demonstrated a granular cell tumor of the neurohypophysis, which when stained proved negative for pituitary hormones and GHRH. This case represents the first reported association between a granular cell tumor of the neurohypophysis and acromegaly. Granular cell tumor of the neurohypophysis could be added to the restricted list of neoplastic causes of acromegaly secondary to hypersecretion of a GH-releasing substance.
authors.affiliation: Department of Neurosurgery, Istituto di Ricovero e Cura a Carattere Scientifico San Raffaele, University of Milan, Milano, Italy. losa.marco@hsr.it
authors.forename: M
authors.initials: M
authors.lastname: Losa
authors.forename: W
authors.initials: W
authors.lastname: Saeger
authors.forename: P
authors.initials: P
authors.lastname: Mortini
authors.forename: C
authors.initials: C
authors.lastname: Pandolfi
authors.forename: M R
authors.initials: MR
authors.lastname: Terreni
authors.forename: G
authors.initials: G
authors.lastname: Taccagni
authors.forename: M
authors.initials: M
authors.lastname: Giovanelli
mesh_terms: D000172:Acromegaly / Q000473:pathology*; D000328:Adult; D003937:Diagnosis, Differential; D005260:Female; D016586:Granular Cell Tumor / Q000473:pathology*; D013007:Growth Hormone-Releasing Hormone / Q000032:analysis; D006801:Humans; D007124:Immunoenzyme Techniques; D008279:Magnetic Resonance Imaging; D008854:Microscopy, Electron; D010904:Pituitary Gland, Posterior / Q000473:pathology*; D010911:Pituitary Neoplasms / Q000473:pathology*
chemical_list: D013007:Growth Hormone-Releasing Hormone