Iris metastasis from lung adenocarcinoma diagnosed solely through aqueous humor cytology: A case report

We report a unique case of iris metastasis from epidermal growth factor receptor (EGFR)-positive lung adenocarcinoma, diagnosed solely by cytologic analysis of aqueous humor without tissue biopsy.

A 56-year-old man with a known history of lung adenocarcinoma presented with unilateral iris masses, anterior chamber inflammation, and secondary glaucoma. Intraocular pressure was initially controlled with cataract surgery combined with microhook trabeculotomy. However, the pressure re-elevated despite maximal topical antiglaucoma therapy (including a prostaglandin analog, beta-blocker, carbonic anhydrase inhibitor, alpha-2 agonist, and Rho-kinase inhibitor) and oral acetazolamide. Three sessions of transscleral cyclophotocoagulation were performed. In addition, two intravitreal injections of aflibercept (2.0 mg each) were administered for rubeosis iridis. Aqueous humor obtained via anterior chamber paracentesis immediately before intravitreal injection demonstrated Class V adenocarcinoma cells on cytology, allowing the diagnosis of iris metastasis without iris biopsy.The lesions subsequently enlarged, and similar iris lesions appeared in the fellow eye during the final 1 month before the patient's death. Systemic disease progression became evident during the final 1 month before death, and the patient ultimately succumbed 9 months after the initial visit. Conclusions and Importance: This is among the few reported cases of iris metastasis confirmed solely by aqueous cytology. This case underscores the diagnostic utility of anterior chamber paracentesis as a less invasive yet reliable alternative to iris biopsy in carefully selected patients. It also highlights the clinical course and therapeutic challenges in managing anterior segment metastasis from epithelial tumors such as lung cancer.