Cutaneous malignant melanoma in a rabbit

By Alex Civello

A 4-year-old rabbit presented with a 3cm diameter skin mass on the neck. The referring vet aspirated the mass and submitted smears for cytology. Images of the cytology are shown.

Figures 1 & 2 – X100 oil immersion – There was abundant free melanin pigment in the background. The cells were polygonal to spindled and had a variable amount of cytoplasmic melanin pigment. There was marked cellular pleomorphism and variation in nuclear size, consistent with malignancy.

Final diagnosis

Malignant melanoma

Discussion

Melanomas in the skin of rabbits are uncommon. In a retrospective study (von Bomhard et al., 2007), of 190 skin tumours in 179 pet rabbits, 8 were diagnosed as malignant melanomas. Metastasis to the internal viscera, including lungs, liver, spleen, and kidneys is reported.

Reference

Von Bomhard et al. (2007). Cutaneous neoplasms in Pet Rabbits: A Retrospective Study. Vet Pathol 44:579-588.