Ophthalmic Pathology: Enucleation for a Pigmented Iris Lesion
A 55-year-old woman undergoes enucleation for a large pigmented iris lesion with extrascleral extension. The eye shows a heavily pigmented mass arising from the ciliary body and iris, with epithelioid cells, prominent nucleoli, and mitotic figures (5 per 10 high-power fields). There is no extrascleral extension on histology, but the tumor is 18 mm in largest dimension. The patient asks about prognosis. You are the pathologist reviewing the case.
1. What is your diagnosis, and what prognostic factors do you report?
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The diagnosis is uveal melanoma, epithelioid cell type. Prognostic factors include largest tumor dimension (18 mm indicates high risk), epithelioid cell type, mitotic rate, and the presence of extrascleral extension (not seen here). Other factors: tumor location (ciliary body involvement), genetic testing (BAP1, monosomy 3), and vascular loops. The pathology report should include these features. The prognosis is guarded due to the large size and epithelioid cells. The patient should be referred for surveillance for metastasis, as uveal melanoma most commonly metastasizes to the liver.
2. How do you address the discrepancy between the clinical impression of extrascleral extension and the histologic findings?
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The clinical impression may have been based on imaging or gross examination, but histology is the gold standard. The absence of extrascleral extension on histology is favorable, but the large size and epithelioid cells still confer high risk. The pathologist should communicate that the final histologic staging may differ from clinical staging and that the prognosis is based on the histologic features. Recommend molecular testing (e.g., gene expression profiling) to further refine risk. The patient should be counseled that the final pathology provides more accurate prognostic information.