Immunohistochemical Findings in Epiretinal Membrane after Long-Term Silicone Oil Tamponade: a Case Report

PURPOSE: To report pre- and post-operative macular optical coherence tomography (OCT) and immunohistochemical findings in a case of long-lasting silicone oil tamponade followed by silicone oil removal and epimacular membrane peeling. METHODS: A 69-year-old man with long-standing silicone oil tamponade and an epiretinal membrane at the posterior pole in his right eye (RE) underwent silicone oil/BSS exchange with epiretinal membrane peeling. Preoperatively, RE best-corrected visual acuity was 20/200 and macular OCT examination revealed a small increase in foveal thickness (250 microm) with the appearance of a linear hyper-reflective signal at the foveal vitreoretinal interface and a thicker (440 microm) hyperreflective finding causing posterior shadowing at the vitreoretinal interface inferiorly to the fovea. Histopathologic and immunohistochemical study of the specimen including the epiretinal membrane was performed. RESULTS: Light microscopy revealed extensive rounded empty spaces interpreted as silicone oil bubbles in the preretinal membrane. Macrophages marker (CD68) positive staining cells were found surrounding the empty spaces within the preretinal membrane and several empty spaces were observed intracellularly within macrophage cytoplasm. Thirty days after surgery best-corrected visual acuity was 20/60 and OCT examination showed an evident decrease in foveal thickness (220 microm) with the disappearance of any hyper-reflective signal at the vitreoretinal interface referable to an epiretinal membrane. CONCLUSIONS: The immunohistochemical study showed both silicone oil droplets and macrophagic cells embedded in the epiretinal membrane. Postoperative OCT demonstrated retinal recovery after silicone oil removal and epiretinal membrane peeling, thus justifying an unexpected visual acuity recovery despite the very long term tamponade.