Fig. 2.

Histologic features of the tumor (hematoxylin-eosin): epithelioid cells organized in nests with fibrous strands interposed, showing round ovular nuclei with finely scattered chromatin and scarce cytoplasm (a). Perineural spread: tumor cells invading the perineurium (b). Intravascular growth: clot of neoplastic cells inside the lumen of a small vessel (c). Nodal metastasis with extranodal extension: residual lymphoid parenchyma invaded by malignant cells; infiltrated fat tissue is also visible (d)