A 68-year-old Caucasian man with fair skin and light-colored irises presents for routine ophthalmologic examination. Fundoscopy reveals a dome-shaped pigmented subretinal mass **A** with overlying orange lipofuscin and surrounding subretinal fluid. B-scan ultrasonography confirms low-medium internal reflectivity with choroidal excavation. Fine-needle aspiration biopsy demonstrates monosomy 3 with 8q gain. Which of the following best describes the expected natural history and primary metastatic pattern of the lesion marked **A**?

Explanation

## Why "Hematogenous spread predominantly to the liver, with 5-year survival in metastatic disease approximately 15%" is right The dome-shaped pigmented mass **A** is a choroidal melanoma, the most common primary intraocular malignancy in adults. The presence of monosomy 3 with 8q gain indicates high metastatic risk. Choroidal melanoma spreads hematogenously, with the liver being the most common site of metastatic disease (~90% of metastases), and metastatic uveal melanoma carries a uniformly poor prognosis with 5-year survival approximately 15% (Yanoff Ophthalmology 5e, Ch 8.13; COMS trials). This is a key exam pearl: uveal melanoma differs from cutaneous melanoma in its propensity for liver metastasis and poor response to checkpoint inhibitors. ## Why each distractor is wrong - **Lymphatic spread to regional lymph nodes, with subsequent pulmonary involvement as the most common site**: Choroidal melanoma does not spread via lymphatic channels; it spreads hematogenously. While lung involvement can occur, it is not the most common metastatic site—the liver is overwhelmingly predominant (~90% of mets). - **Direct orbital extension with subsequent spread to the brain via the optic nerve sheath**: Although extrascleral extension can occur in advanced tumors (requiring orbital exenteration), this is not the primary or most common pattern of spread. Hematogenous dissemination occurs early and is the dominant metastatic pathway. - **Local invasion of the ciliary body and iris with anterior chamber seeding**: Local anterior spread is not the characteristic metastatic pattern of choroidal melanoma. The tumor spreads systemically via the bloodstream, not by local anterior chamber involvement. **High-Yield:** Choroidal melanoma → hematogenous spread → liver metastases (~90%) → uniformly fatal within months without effective therapy; monosomy 3 + 8q gain = high metastatic risk. [cite: Yanoff Ophthalmology 5e Ch 8.13 (Uveal Melanoma); COMS trials]