[Histopathological study of retrolental membranes secondary to persistent hyperplastic primary vitreous].

Objective: To study the pathological characteristics of retrolental membranes (RLMs) secondary to persistent hyperplastic primary vitreous (PHPV), and to discuss the possible pathogenesis of PHPV.

Methods: Experimental study. Six RLMs obtained from six patients with PHPV during vitrectomy were examined by light microscopy (HE & PAS staining). All of them were observed with proliferating cell nuclear antigen (PCNA) immunostaining, together with collagen I, factor VIII related antigen, smooth muscle actin (SMA), epithelial membrane antigen (EMA), neuron specific enolase (NSE) and glial fibrillary acidic protein (GFAP) staining. Apoptosis were detected by terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate nick-end labeling (TUNEL).

Results: Light microscopy showed that the RLM was a dense connective tissue with numerous inflammatory cells including mast cells and lymphocytes. PAS staining showed that RLMs contained a larger amount of polysaccharides. Histopathology and immunohistochemistry showed that there were vascular channels, smooth muscle cells, nervous cells and epithelial cells scattered in RLMs. Collagen I was the main component of RLMs. PCNA-positive nuclei were widely found in RLMs. TUNEL-positive nuclei were also found in all RLMs, as well as in the posterior subcapsular epithelial cells of lens.

Conclusions: The cell types of RLMs secondary to PHPV are similar to those of the primary vitreous. It is possible that the mechanism of the progression of RLMs is the over-development and incomplete regression of the retrolental vascular system. Inflammation may play an important role in the regression of RLMs.