Canine Cutaneous Melanocytic Tumors: What Separates Melanocytoma from Melanoma on the Slide

A small, well-pigmented mass on a dog's skin is almost always benign — but "almost always" isn't a diagnosis. Here's how mitotic count, nuclear atypia, thickness, and the Ki-67 proliferation index separate a melanocytoma from the malignant melanomas that look deceptively similar.