• Courtesy of Patricia Chévez-Barrios, MD.
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    Ocular Pathology/Oncology

    Fine-needle aspiration biopsy (FNAB) of choroidal tumor. A, Cytologic liquid-based preparation displays prominent nucleoli (arrow) and some brown pigment (arrowhead) suggestive of melanoma. B, Cell block of the aspirated cells, stained with HMB-45 using a red chromogen, is positive, confirming the diagnosis of melanoma. Notice the difference between the red chromogen (arrows) and the brown melanin (arrowheads).