PMC5301116_01
a Chest X-ray showing opacification of the right hemithorax. b Video-assisted thoracoscopic surgery images showing diffuse pleural thickening. c HMB-45 antibody staining of melanoma cells (x10). d HE stain showing large melanoma cells with pleomorphic nuclei and occasional cherry red nucleoli (x40). e Type II melanosome with cross-striated lattice in an enclosed membrane. Inset Type III melanosome with increased deposition of electron-dense melanin. f Type III melanosomes superimposed on lattice. Inset Type IV melanosomes with increased deposition of highly electron-dense melanin.
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Chest X-ray revealed a large right-sided pleural effusion (Fig. 1a). As the patient's pleural effusion was refractory to CLL treatment, video-assisted thoracoscopic surgery was performed, which demonstrated diffuse nodular thickening of both visceral and parietal layers of the pleura (Fig. 1b). A biopsy of these lesions revealed enlarged cells with an increased nuclear-cytoplasmic ratio and pleomorphic nuclei with occasional cherry red nucleoli (Fig. 1d). Immunohistochemistry studies demonstrated positive staining with HMB-45 (Fig. 1c) and S-100 protein. Electron microscopy revealed type II melanosomes with cross-striated lattice in an enclosed membrane (Fig. 1e), type III melanosomes with increased deposition of electron-dense melanin, and type IV melanosomes with highly electron-dense melanin (Fig. 1f).