title: Prolactin-producing pituitary tumor: resistance to dopamine agonist therapy. Case report.
abstract: A 14-year-old girl presented with a rapidly growing, invasive prolactin-producing pituitary tumor that failed to respond to dopamine agonist medication. Histological, immunocytochemical, and ultrastructural studies of the surgically removed tissue revealed a pleomorphic, chromophobic, or slightly acidophilic pituitary tumor that was immunoreactive for prolactin and that, according to electron microscopy, consisted of atypical lactotrophs showing no evidence of cell shrinkage. In situ hybridization demonstrated large amounts of prolactin messenger ribonucleic acid (mRNA), moderate amounts of estrogen receptor mRNA and dopamine (D2) receptor mRNA, and an absence of growth hormone mRNA in the tumor cells. Because D2 receptor mRNA was present in the tumor, causes other than D2 receptor loss may have been responsible for the resistance of the lactotrophs to dopamine agonist administration.
authors.affiliation: Department of Pathology, St. Michael's Hospital, University of Toronto, Ontario, Canada.
authors.forename: K
authors.initials: K
authors.lastname: Kovacs
authors.forename: L
authors.initials: L
authors.lastname: Stefaneanu
authors.forename: E
authors.initials: E
authors.lastname: Horvath
authors.forename: M
authors.initials: M
authors.lastname: Buchfelder
authors.forename: R
authors.initials: R
authors.lastname: Fahlbusch
authors.forename: W
authors.initials: W
authors.lastname: Becker
mesh_terms: D000236:Adenoma / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D000293:Adolescent; D000634:Aminoquinolines / Q000627:therapeutic use*; D001971:Bromocriptine / Q000627:therapeutic use*; D018491:Dopamine Agonists / Q000627:therapeutic use*; D004351:Drug Resistance; D005260:Female; D006801:Humans; D008854:Microscopy, Electron; D010911:Pituitary Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D011388:Prolactin / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000032:analysis; D011954:Receptors, Dopamine / Q000032:analysis; D017448:Receptors, Dopamine D2 / Q000032:analysis; D011960:Receptors, Estrogen / Q000032:analysis
chemical_list: D000634:Aminoquinolines; D018491:Dopamine Agonists; D012333:RNA, Messenger; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D011960:Receptors, Estrogen; D001971:Bromocriptine; C046650:quinagolide; D011388:Prolactin