A Case of Intraocular Metastasis of Lung Cancer Diagnosed Using Cell Block Preparation of the Vitreous Humor

Background/Aim: Masquerade syndrome is characterized by uveitis-like manifestations caused by tumor cell infiltration into the ocular tissues. The aim of the study was to report a lung cancer patient with persistent unilateral vitreous opacity, who was eventually diagnosed with masquerade syndrome using cell block preparation. Case Report: An 82-year-old female complained of blurred vision in her left eye (OS). Because of pulmonary adenocarcinoma, she had previously received anticancer drug treatment at another Hospital and achieved partial remission. Ophthalmic examinations revealed anterior chamber inflammation and vitreous opacity OS. Corticosteroid eye drops were administered, but the inflammation did not improve, and was referred to the Hokkaido University Hospital. The left best-corrected visual acuity was 0.1 with normal intraocular pressure. Anterior chamber inflammation was 2+ cells, and vitreous haze was 4+ OS. B-mode ultrasonography showed diffuse heterogeneous high echoic changes in the vitreous cavity. She underwent vitrectomy, and cell block preparation of the vitreous infusion fluids was performed. Cytopathology revealed adenocarcinoma cells with a high nuclear/cytoplasmic ratio and glandular formation. The immunocytochemical study showed that tumor cells were positive for thyroid transcription factor-1 (TTF-1), napsin A, and CK7, therefore diagnosis of masquerade syndrome due to intraocular metastasis of pulmonary adenocarcinoma was reached. Chemoradiotherapy was administered, and the eye got phthisis bulbi after irradiation 2 years after diagnosis. Conclusion: Cell block preparation using vitreous humor may be useful in the diagnosis and management of intraocular metastasis of pulmonary adenocarcinoma in patients with prolonged vitreous opacity.