Fig. 4.

Pathology images of the tumor. (A) Gross appearance of the well-circumscribed firm mass with tan cut surface and no necrosis. (B) H&E staining view showing sheets of large epithelioid or polygonal tumor cells with eosinophilic cytoplasm and atypical vesicular nuclei with variably prominent nucleoli (arrows). The tumor cells are intimately admixed with inflammatory infiltrate consisting of lymphocytes (star) and neutrophils (arrowhead). (C) ALK protein immunohistochemistry reveals cytoplasmic staining.