A 9-year-old Labrador retriever is presented for a recheck after amputation of its right front leg six months earlier to treat a high-grade sarcoma. Recently, the owner has noticed a mass on the dog's head. The mass is aspirated, and the sample is smeared, air-dried, and stained with Wright's-Giemsa stain (50X and 100X).

What is your primary differential in this case?

a) Round cell tumor

b) Soft tissue sarcoma

c) Benign epithelial tumor

d) Lymphocytic inflammation