Figure 3

Photomicrographs of the mesenteric mass. (A) At lower power field, the tumor was observed to be composed of epithelioid tumor cells with clear to eosinophilic cytoplasms. The epithelioid tumor cells were arranged around delicate vasculature. (B) The epithelioid tumor cells had round to oval vesicular nuclei with 1-2 centrally located small nucleoli, and mitotic figure was observed in the tumor cells (black arrow). (C) Extensive necrotic areas were observed in the tumor. Note the atypical tumor cells with irregular hyperchromatic nuclei at the periphery of necrosis. (D) One of enlarged mesenteric lymph nodes was observed to be involved by tumor cells. Immunohistochemical analysis of the mesenteric mass showed epithelioid tumor cells were diffusely positive for melanocytic markers, HMB-45 (E) and Melan-A (F). (A and C, H&E staining with original magnification × 200; B, H&E staining with original magnification × 400; D, H&E staining with original magnification × 100; E-F, Immunohistochemical staining with original magnification, ×400).