Analysis of pathohistological characteristics of pterygium

Abstract

Pterygium internum (external eye layer) shows great recurrence tendency after surgical removal. Its etiology is still unclear and represents a significant problem. The main goal of our study was to explore the interrelationships of pathohistological characteristics of pterygium, namely presence of inflammation, vascularisation degree and fibrinoid changes and on the basis of their analysis to test the possibility of predicting its evolution and recurrence. The analysis was performed on the material taken from 55 patients surgically treated by the technique of Arlt. The specimens were stained using the classical histochemical methods: hematoxylin-eosin (HE), Masson's trichrome, Gomori's reticulin stain and PAS technique. Pterygium is mostly covered by conjunctival epithelium, while in the cap region shows morphology of modified stratified squamous epithelium of the cornea. Structural basis of the epithelium is composed of continuous basal lamina and continuous connective fibers underneath. This connective basis shows fibrinoid changes in the form of oval islets of different size, parallel to convexity of pterygium, or is in the form of unified focus. The number, caliber and the type of blood vessels showed excessive variability. Pathohistological analysis of morphological characteristics of pterygium is adequate basis for prediction of recurrences; as they present the biggest concern in treatment of this widely spread disease.

Extracellular matrix and fibroblast injection produces pterygium-like lesion in rabbits

“…The absence of significant elastotic changes in the analyzed tissues could be associated with the method used to induce the pterygium-like tissue formation (eliciting inflammatory immune response and/or fibroblastic cell proliferation, not associated with UV light exposure) and to the short period after which histological analysis was performed. Otherwise, cellular edema was similar between right eyes and human pterygium, comparable with the observations of previous reports [19]. Although similar protocols in mice models [10, 11] have succeeded in eliciting and inflammatory response and tissue growth over the injection site (subconjunctival), histologic descriptions when available, have only shown neo-vessels, cell migration and extracellular matrix breakdown with no evidence of acanthosis, elastosis or stromal/epithelial inflammation.…”

“…In our analysis, tissues of both groups showed neovascularization with a slight increased level in right eyes, but in a lower grade than that observed in human pterygium [20]. Nonetheless, the number of new vessels in human pterygium has been reported as extremely variable [19, 20]. In human pterygium, redness and fleshiness are correlated with the vascular density and stromal fibrosis, while the extent of the pterygium over the cornea has an inverse relation with the stromal elastosis [18].…”

“…The most distinctive feature of human pterygium is neovascularization [19, 21]. In our analysis, tissues of both groups showed neovascularization with a slight increased level in right eyes, but in a lower grade than that observed in human pterygium [20].…”

The excision-generated effect of pterygium on the related corneal astigmatism

“…Hot climatic-based regions, high levels of sun and/or UV lights, are the most places that pterygia could be noticed in (Chui et al, 2011;Hall, 2016). However, ocular dryness, irritation, and dominance (all-time compensatory-opening of eye) are extra etiological factors that could also induce pterygiurn (Accorinti et al, 2014;Antony, 2017;Džunić et al, 2010;Essuman et al, 2014;Ishioka et al, 2001;Malekifar et al, 2017). Various degrees of corneal distortion (CD) and corneal astigmatism (CA) can be developed following the occurrence and the progression of pterygium (Avisar et al, 2000;Macarie and Macarie, 2016;MohammadSalih and Sharif, 2008;Oh and Wee, 2010).…”

Preliminary evidence of the presence of lymphatic vessels immunoreactive for D2-40 and Prox-1 in human pterygium

“…Pterygium is a disease characterized by surface ocular lesions associated with chronic ultraviolet exposure in which the primary effect is a solar actinic elastosis within the stroma and all other changes are secondary to the primary effect (1)(2)(3)(4)(5)(6)(7). Pterygium is characterized by cellular proliferation, inflammatory infiltration, fibrosis, angiogenesis, and extracellular matrix breakdown; the lesion begins to grow from limbal epithelium and invades the cornea centripetally followed by conjuntival epithelium, exhibiting degenerative and hyperplastic changes (1-7).…”