Answer
Histologic evaluation of the tumor after enucleation can confirm the diagnosis and determine the prognosis (see the images below). [6]

As noted (see Pathophysiology), 3 distinct cell types are recognized to occur in uveal melanomas: (1) spindle A, (2) spindle B, and (3) epithelioid. Spindle A cells have elongated nuclei and uncommonly have mitotic figures (see the image below).
Spindle B cells have a prominent nucleolus (see the image below). They are found more commonly and also have an elongated profile but are slightly larger than spindle A cells.
Epithelioid melanoma cells are highly anaplastic, poorly cohesive, and have considerable morphologic variation (see the figure below). They tend to resemble epithelial cells and contain frequent mitotic figures.
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Color photograph of a dome-shaped choroidal melanoma.
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Early fluorescein angiogram of choroidal melanoma showing intrinsic vascularity.
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Late fluorescein angiogram of choroidal melanoma showing early diffuse staining.
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B-scan ultrasound showing acoustic hollowing and uveal excavation in posterior choroidal melanoma.
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A-scan ultrasound of choroidal melanoma showing low-to-medium internal reflectivity.
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B-scan ultrasound showing acoustic hollowing in intraorbital extension of a posterior choroidal melanoma.
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T2-weighted MRI showing a small anterior choroidal melanoma in the left eye.
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Transpupillary photograph showing a posterior choroidal melanoma.
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Photograph showing an enucleated eye with advanced choroidal melanoma with transscleral extension.
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Histologic section of an enucleated eye showing a large dome-shaped choroidal melanoma.
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Histologic section of an enucleated eye showing a medium-sized mushroom-shaped choroidal melanoma with associated exudative retinal detachment.
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Choroidal melanoma. Histologic section showing spindle A cells in a uveal nevus.
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Choroidal melanoma. Histologic section showing spindle B cells in a uveal melanoma.
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Choroidal melanoma. Histologic section showing epithelioid cells in a uveal melanoma.
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Photograph showing a skin metastasis of a posterior choroidal melanoma.
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Intraoperative photograph showing placement of a radioactive plaque for posterior choroidal melanoma.