title: Pituitary adenomas that show a faint GH-immunoreactivity but lack fibrous body: Pit-1 adenoma with endocrinologically low activity.
abstract: Growth hormone (GH)-producing pituitary adenomas have been classified into densely and sparsely granulated adenomas. The latter are chromophobic with weak GH-positivity and characteristically possess fibrous body (FB), aggregation of cytokeratin filaments. We report eight cases of unusual chromophobic adenomas. GH-immunoreactivity was detected in most adenoma cells in five cases and scattered in three cases. However, it appeared much weaker than that seen in ordinary GH-producing adenomas because of spotty immunoreactivity. Although intracytoplasmic organelles were well-developed, secretory granules were small and sparse. FB was not identified in any cases. Thyroid-stimulating hormone was positive in four cases. Pit-1 protein was positive in all eight cases. A weak labeling with GH probe was detected in two of two cases examined by in situ hybridization. Acromegalic features were evident in four cases, while mild or absent in four cases. GH levels were below 5 microg/l in four cases and 5-10 microg/l in the remaining cases. Macroadenomas and invasive adenomas were seen in seven and six cases, respectively.Pituitary adenomas that show a faint GH-immunoreactivity but lack FB do not fit the established classification. These adenomas may be a distinct pituitary adenoma type of Pit-1 lineage with endocrinologically low activity.
authors.affiliation: Department of Human Pathology, Institute of Health Bioscience, University of Tokushima Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Yoneda
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Sano
authors.forename: Shozo
authors.initials: S
authors.lastname: Yamada
authors.forename: Abdulkader
authors.initials: A
authors.lastname: Obari
authors.forename: Zhi Rong
authors.initials: ZR
authors.lastname: Qian
authors.forename: Elaine Lu
authors.initials: EL
authors.lastname: Wang
authors.forename: Naoko
authors.initials: N
authors.lastname: Inosita
authors.forename: Eiji
authors.initials: E
authors.lastname: Kudo
mesh_terms: D000328:Adult; D005260:Female; D019382:Human Growth Hormone / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012334:RNA, Neoplasm / Q000096:biosynthesis / Q000235:genetics; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D012333:RNA, Messenger; D012334:RNA, Neoplasm; D019382:Human Growth Hormone