ALT Histological examination revealed a tumor composed of cells with irregular, sometimes grooved nuclei, eosinophilic cytoplasm, and frequent mitoses (black circles), and with scattered pleomorphic multinucleated or binucleated cells (arrows) (A). Hemophagocytic activity was present in some cells (B). A brown cytoplasmic or extracellular pigment was present (C), which corresponded to hemosiderin deposits as demonstrated by Perl's immunostaining (D). Neoplastic cells were positive for CD68 (E), CD163 (F), and focally positive for CD4 (G). CD3 immunostaining demonstrated an abundant infiltrate of small lymphocytes (H).