Unilateral Scleral Icterus as a Rare Presentation of Choroidal Metastasis in Transdifferentiated EGFR-Mutant Lung Cancer: A Case Report and Review of the Literature.

Unilateral scleral icterus is an extremely rare clinical finding and is not typically associated with systemic hyperbilirubinemia. We report the case of a 28-year-old man with biopsy-proven transdifferentiated neuroendocrine lung carcinoma arising from EGFR-mutant non-small cell lung cancer (NSCLC), who presented with painless, localized yellow discoloration of the temporal sclera of the right eye without systemic features of jaundice. Ophthalmic examination revealed reduced visual acuity in the affected eye and an elevated temporal chorio-retinal mass. B-scan ultrasonography demonstrated a dome-shaped lesion measuring 6 mm in thickness with moderate internal reflectivity. Laboratory investigations, including serum bilirubin and liver enzymes, were normal, and systemic imaging showed no hepatic or biliary pathology. The patient was diagnosed with choroidal metastasis and treated with urgent external beam radiotherapy followed by systemic chemotherapy. The unilateral scleral icterus was attributed to localized xanthochromic changes related to the choroidal metastasis. This case highlights unilateral scleral icterus as a rare ocular sign of choroidal metastasis. To our knowledge, this is the first reported case in which choroidal metastasis-specifically from transdifferentiated neuroendocrine lung carcinoma-presented with unilateral scleral yellowing. Previously published cases of unilateral scleral icterus have been associated with subconjunctival or suprachoroidal hemorrhage, prior ocular surgery, localized facial malignancy, or treatment-related vascular changes rather than metastatic infiltration. This report expands the differential diagnosis of unilateral scleral discoloration and underscores the importance of prompt ophthalmologic evaluation in oncology patients with new ocular findings, even in the absence of visual symptoms or biochemical evidence of jaundice. It also emphasizes the value of multidisciplinary collaboration between ophthalmology and oncology in recognizing atypical manifestations of advanced malignancy.