title: Vasculogenic Mimicry in Clinically Non-functioning Pituitary Adenomas: a Histologic Study.
abstract: The term "vasculogenic mimicry" (VM) refers to the phenomenon in which vascular-like channels, which are not lined by endothelial cells, are formed in tumors. Since its discovery in 1999, it has been observed in several tumor types and is proposed to provide blood perfusion to tumors in absence of co-apted or neo-angiogenic blood vessels. Pituitary tumors are generally slow growing, benign adenomas which are less vascularized than the normal pituitary gland. To date, VM in pituitary adenomas has not been described. In this histological study, we assessed the presence of VM in a series of surgically resected clinically non-functioning pituitary adenomas (NFPAs) using CD34 and Periodic Acid-Schiff (PAS) double staining. To identify VM, slides were assessed for the presence of CD34-negative and PAS-positive channels indicating that they were not lined by endothelial cells. The histological staining pattern suggestive of VM was noted in 22/49 (44.9%) of the specimens studied. VM was observed in both recurring and non-recurring NFPAs. The incidence of VM present varied from case to case and within groups. There was no association between the presence of VM and gender, tumor size, Ki-67 index, recurrence or cavernous sinus invasion. VM was not noted in cases of non-tumorous pituitaries. Our findings suggest the existence of a complementary perfusion system in pituitary adenomas, implying potential clinical implications with respect to response to therapy and clinical course. Further research is warranted to confirm the presence of VM in pituitary adenomas to elucidate its clinical relevance in patients diagnosed with a pituitary adenoma.
authors.affiliation: Department of Surgery, Division of Neurosurgery and the Keenan Research Centre for Biomedical Science at the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada.
authors.forename: Joseph
authors.initials: J
authors.lastname: Di Michele
authors.affiliation: Department of Laboratory Medicine, Division of Pathology and the Keenan Research Centre for Biomedical Science at the Li Ka Shing Knowledge Institute, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B1W8, Canada. rotondof@smh.ca.
authors.forename: Fabio
authors.initials: F
authors.lastname: Rotondo
authors.affiliation: Department of Laboratory Medicine, Division of Pathology and the Keenan Research Centre for Biomedical Science at the Li Ka Shing Knowledge Institute, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B1W8, Canada.
authors.forename: Kalman
authors.initials: K
authors.lastname: Kovacs
authors.affiliation: Department of Neurosurgery, Hospital Pablo Tobon Uribe and Clinica Medellin, Medellin, Colombia.
authors.forename: Luis V
authors.initials: LV
authors.lastname: Syro
authors.affiliation: Department of Laboratory Medicine, Division of Pathology and the Keenan Research Centre for Biomedical Science at the Li Ka Shing Knowledge Institute, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B1W8, Canada.
authors.forename: George M
authors.initials: GM
authors.lastname: Yousef
authors.affiliation: Department of Surgery, Division of Neurosurgery and the Keenan Research Centre for Biomedical Science at the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Cusimano
authors.affiliation: Australian School of Advanced Medicine, Department of Neurosurgery, Macquarie University Hospital, Sydney, Australia.|Garvan Institute of Medical Research, Sydney, Australia.
authors.forename: Antonio
authors.initials: A
authors.lastname: Di Ieva
mesh_terms: D000236:Adenoma / Q000473:pathology*; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000473:pathology*
keywords: Biomarkers; Microvascularity; Pathology; Pituitary adenoma; Vasculogenic mimicry