title: Equine deep stromal abscesses (51 cases - 2004-2009)--Part 2: the histopathology and immunohistochemical aspect with attention to the histopathologic diagnosis, vascular response, and infectious agents.
abstract: OBJECTIVE
  To investigate histopathologic and immunohistochemical aspects of equine deep stromal abscesses (DSA) with a focus on the histopathologic diagnosis, presumptive etiology, and the immunohistochemical expression of three angiogenesis-related factors: vascular endothelial growth factor-A (VEGF-A), pigment epithelium-derived factor (PEDF), and interleukin-1 receptor antagonist (IL-1ra).
  
  
  METHODS
  Paraffin-embedded biopsy samples from 51 DSA. The biopsies were collected from full-thickness penetrating keratoplasty or split-thickness lamellar keratoplasty surgeries at the University of Florida Veterinary Medical Center in the period from 2004 to 2009.
  
  
  METHODS
  The histopathologic and immunohistochemical findings were tested for association between each other. Prevalence calculation and test for association with qualitative data analysis was used for data evaluation.
  
  
  RESULTS
  Fungal hyphae were found histologically in 47.1% (n = 24) of the DSA cases. Histopathologically, most fungal DSA showed suppurative keratitis (n = 34; 66.7%) and little to no stromal vascularization infiltrating the abscess (negative association, P = 0.005). All three angiogenesis-related factors were expressed to some degree in DSA tissue. A negative association between VEGF-A and PEDF when compared to the presence of fungal hyphae (P < 0.001, P = 0.023) indicated that cases positive for these two factors will most probably not have fungal hyphae present.
  
  
  CONCLUSIONS
  Abnormally decreased VEGF-A expression is suggested as the reason for the slow vascularization and delayed resolution of fungal DSA, whereas PEDF and IL-ra did not seem to have any influence on the vascularization process. Clinical and histopathologic characteristics of DSA make it possible to suggest an etiology for an equine DSA with an unknown etiology.
authors.affiliation: Faculty of Health and Medical Sciences, Department of Veterinary Clinical and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark; Departments of Large and Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA; Department of Veterinary Clinical Sciences, Comparative Ophthalmology, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN, USA.
authors.forename: Michala
authors.initials: M
authors.lastname: de Linde Henriksen
authors.forename: Pia Haubro
authors.initials: PH
authors.lastname: Andersen
authors.forename: Kristy
authors.initials: K
authors.lastname: Mietelka
authors.forename: Lisa
authors.initials: L
authors.lastname: Farina
authors.forename: Preben D
authors.initials: PD
authors.lastname: Thomsen
authors.forename: Caryn E
authors.initials: CE
authors.lastname: Plummer
authors.forename: Brendan G
authors.initials: BG
authors.lastname: Mangan
authors.forename: Steffen
authors.initials: S
authors.lastname: Heegaard
authors.forename: James K
authors.initials: JK
authors.lastname: Coleman
authors.forename: Nils
authors.initials: N
authors.lastname: Toft
authors.forename: Dennis E
authors.initials: DE
authors.lastname: Brooks
mesh_terms: D000038:Abscess / Q000175:diagnosis / Q000276:immunology / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D000818:Animals; D003316:Corneal Diseases / Q000175:diagnosis / Q000276:immunology / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D003319:Corneal Stroma / Q000098:blood supply / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D005136:Eye Proteins / Q000378:metabolism; D006734:Horse Diseases / Q000175:diagnosis* / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D006736:Horses; D006801:Humans; D053590:Interleukin 1 Receptor Antagonist Protein / Q000378:metabolism; D009414:Nerve Growth Factors / Q000378:metabolism; D015843:Serpins / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D000099174:Pigment Epithelium-Derived Factor
chemical_list: D005136:Eye Proteins; D053590:Interleukin 1 Receptor Antagonist Protein; D009414:Nerve Growth Factors; D015843:Serpins; D042461:Vascular Endothelial Growth Factor A; D000099174:Pigment Epithelium-Derived Factor
keywords: deep stromal abscess; equine; histopathology; interleukin-1 receptor antagonist; pigment epithelium-derived factor; vascular endothelial growth factor-A