Figure 1

Epithelioid fibrous histiocytoma is usually exophytic and well circumscribed with an epidermal collarette (a). The tumor often has prominent small thin and thick-walled vessels, and is composed of polygonal or ovoid cells with variable amounts of palely eosinophilic cytoplasm, vesicular nuclei, and generally small or inconspicuous nucleoli; admixed lymphocytes are present (b). Tumor cells show diffuse expression of ALK (c).