Pigmented melanoma, light micrograph. This is an example of pigment-producing melanoma (animal-type melanoma; equine type melanoma) which is a rare variant that resembles melanocytic tumours occurring in horses and other animals. It is thought to be distinct entity and not related to malignant blue nevus. Most cases present as brown, blue-black, or black solid nodules in 2nd to 4th decade. They are considered to be low-grade lesions with a better prognosis than ordinary melanomas of comparable thickness. The tumours show a dense infiltrate of melanocytes with copious amounts of melanin in the papillary and reticular dermis. The tumour cells are epithelioid or spindle shaped and may be arranged in fascicles or nodules.