This study is a part of the first author's PhD study performed and sponsored by the University of Copenhagen, Denmark (2008–2013). The cases in the study were collected during the first author's residency in comparative ophthalmology at the University of Florida, USA (2009–2012). The first author is now a faculty member at the University of Minnesota (2013-present).
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
Article first published online: 17 OCT 2013
© 2013 American College of Veterinary Ophthalmologists
How to Cite
de Linde Henriksen, M., Andersen, P. H., Mietelka, K., Farina, L., Thomsen, P. D., Plummer, C. E., Mangan, B. G., Heegaard, S., Coleman, J. K., Toft, N. and Brooks, D. E. (2013), 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. Veterinary Ophthalmology. doi: 10.1111/vop.12102
- Article first published online: 17 OCT 2013
- Danish Government PhD grant
- Agustinus Fonden
- deep stromal abscess;
- interleukin-1 receptor antagonist;
- pigment epithelium-derived factor;
- vascular endothelial growth factor-A
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).
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.
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.
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.
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.