title: Prolactin-producing pituitary adenoma associated with prolactin cell hyperplasia.
abstract: A 24-yr-old woman with amenorrhea, galactorrhea, hyperprolactinemia, and sellar mass underwent transsphenoidal surgery. Histologic, immunohistochemical, and electron microscopic investigation revealed a well-differentiated, sparsely granulated prolactin (PRL) cell adenoma of the pituitary showing conclusive PRL immunoreactivity. In the nontumorous adenohypophysis PRL cell hyperplasia was noted. Marked differences were evident between the neoplastic and hyperplastic areas. The tumor consisted of sparsely granulated PRL cells immunoreactive only for PRL. As demonstrated by immunoelectron microscopy, the hyperplastic area comprised monohormonal sparsely granulated PRL cells as well as bihormonal mammosomatotrophs immunoreactive for both PRL and growth hormone. The MIB-1 index was higher whereas microvessel density was lower in the adenoma as compared with the hyperplastic area. In addition, the nontumorous area showed lymphocytic infiltration whereas inflammatory reaction was not seen in the adenoma. This case represents a rare association of a PRL cell adenoma and PRL cell hyperplasia. The fact that these two lesions were contiguous in the surgically removed material raises the possibility that hyperplasia can precede and transform into adenoma.
authors.affiliation: Department of Laboratory Medicine, St. Michael's Hospital, Toronto, Ontario, Canada. svidal@lugo.usc.es
authors.forename: Sergio
authors.initials: S
authors.lastname: Vidal
authors.forename: Eva
authors.initials: E
authors.lastname: Horvath
authors.forename: Luis V
authors.initials: LV
authors.lastname: Syro
authors.forename: Humberto
authors.initials: H
authors.lastname: Uribe
authors.forename: Sandy
authors.initials: S
authors.lastname: Cohen
authors.forename: Kalman
authors.initials: K
authors.lastname: Kovacs
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002455:Cell Division; D005260:Female; D006801:Humans; D006965:Hyperplasia / Q000150:complications* / Q000378:metabolism* / Q000473:pathology*; D016253:Microscopy, Immunoelectron; D010911:Pituitary Neoplasms / Q000150:complications* / Q000378:metabolism* / Q000648:ultrastructure; D015175:Prolactinoma / Q000150:complications* / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D014408:Biomarkers, Tumor