Clinicopathological findings in refractory diabetic macular edema: A case report

• Published in: Biomedical reports 2024-01, Vol.20 (1), p.13, Article 13
• Main Authors: Tanaka, Takayuki, Kase, Satoru, Saito, Michiyuki, Hirose, Ikuyo, Murata, Miyuki, Takakuwa, Emi, Ishida, Susumu
• Format: Article
• Language: English
• Subjects: Acuity; Advanced glycosylation end products; Age; Case Report; Case reports; Cataracts; Cellular structure; Collagen; Diabetes; Diabetes mellitus; Dropsy; Edema; Exudates; Exudation; Eye; Eye surgery; Fibrin; Fibrinogen; Glial fibrillary acidic protein; Growth factors; Hemorrhage; Immunohistochemistry; Insulin lispro; Lesions; Leukocytes (eosinophilic); Medical research; Medicine, Experimental; Monoclonal antibodies; Patients; Plasmin; Polyclonal antibodies; Post-translation; Post-translational modification; Scientific equipment and supplies industry; Vascular endothelial growth factor; Visual acuity; Visual aspects
• ISSN: 2049-9434; 2049-9442
• DOI: 10.3892/BR.2023.1701

The present study describes the case of a patient with refractory diabetic cystoid macular edema who underwent vitrectomy with removal of the cystoid lesion component. The current study also performed histopathological and immunohistochemical analyses of the cystoid lesion component to assess fibrin/fibrinogen and advanced glycation end-products (AGEs) immunoreactivity. A 69-year-old Japanese man presented with visual loss in the left eye due to residual cystoid macular edema (CME) refractory to anti-vascular endothelial growth factor therapy. Best-corrected visual acuity was 1.2 in the right eye (OD) and 0.5 in the left eye (OS). Fundus examination showed dot hemorrhages and hard exudates in the peri-macular region with pan-retinal photocoagulation scars in both eye. Swept-source optical coherence tomography revealed CME with slight hyperreflectivity in the cyst OS. A total of 3 months after the initial visit, pars plana vitrectomy was performed, and the translucent solidified component within the cystoid lesion was isolated. Histopathologically, the excised component was elliptical in shape, measuring 0.7x0.4 mm and exhibited homogeneous eosinophilic material without cellular components. No membranous structure was observed surrounding the component. Immunohistochemistry demonstrated that the tissue was positive for fibrin/fibrinogen and weakly positive for AGEs, but was negative for glial fibrillary acidic protein, type 1 collagen and receptor for AGEs. To the best of our knowledge, the present case report is the first to histopathologically examine the contents of refractory CME, and to immunohistochemically demonstrate that fibrin in diabetic CME may be post-translationally modified by AGEs. These results suggested that fibrin in CME may escape degradation by plasmin due to post-translational modifications.