The pathologic characteristics of pingueculae on autofluorescence images

Abstract

Purpose: To analyze the autofluorescence (AF) properties of pinguecula using cobalt-blue and yellow filters and to investigate the nature and pathogenesis of pingueculae using histochemical and immunohistochemical staining.

Methods: Fifty pingueculae in 40 patients were included in this study. AF of the pingueculae was observed and analyzed using a cobalt-blue filter with an additional yellow filter on a slit-lamp. Hematoxylin-eosin and immunohistochemical stainings were performed on surgical specimens of pingueculae that were prepared from each patient. Immunohistochemical staining included Congo red, Oil Red O, periodic acid-Schiff (PAS), Masson's trichrome, transglutaminase-2 (TG-2), mesenchymal stem cell markers CD29 (β-1-integrin), and CD34.

Results: AF images revealed hyper-AF in the pinguecula area. The AF lesions of pingueculae showed superficial punctuate erosions and avascular lesions. Deposition of eosinophilic and amorphous materials in the subepithelial layer of the pinguecula were observed on hematoxylin-eosin staining. Historeactivities to Congo red, PAS, Oil Red O, alcian blue, and Masson's trichrome were not detected, but immunoreactivities to CD29, CD34, and TG-2 were detected in the pingueculae with AF. However, CD29, CD34, and TG-2 were not detected in the pingueculae without AF.

Conclusions: The AF of pingueculae may be related to CD29, CD34, and TG-2. We suggest that pingueculae with AF have a different pathogenesis compared to pingueculae without AF.

Keywords: Optical imaging; Pinguecula; Transglutaminase 2.

Fig. 1

(A,B) Dilated tortous vessel, no vessel invasion and whitish deposits were seen in the pinguecula area. (C) Multiple erosions were observed in the area of pinguecula autofluorescence (AF). (D-F) Various images of pingueculae AF acquired using a cobalt blue filter with an additional yellow filter on a slit lamp biomicroscope.

Fig. 2

Immunohistochemical staining of pinguecula autofluorescence (AF). (A) Conjunctiva stroma with thinning of the overlying epithelium and calcification were detected. (B) Eosinophilic-stained amorphous material was detected in the subepithelial layer of the conjunctiva. (C-F) No immunoreactivity was detected. (G) Immunoreactivity to transglutaminase-2 was detected in the normal epithelium, normal vessel walls, and elastotic degeneration area of AF. (H,I) Immunoreactivity was detected. (A,B) Hematoxylin-eosin, (C) periodic acid-Schiff, (D) Masson's trichrome, (E) Congo red, (F) Oil Red O, (G) transglutaminase-2, (H) CD29 (β-1-integrin), and (I) CD 34 (×400).