Cutaneous melanomas in rabbits: rare but often fatal

Abstract

An adult male dwarf rabbit (Oryctolagus cuniculus) was presented to the veterinarian due to hind limb lameness. The rabbit was in a reduced body condition. Clinical examination and cytology identified a cutaneous melanoma in the inguinal region. Whole body radiographs identified multifocal radio-opaque masses in both lungs which where assumed to be lung metastases. The animal was euthanized due to the poor prognosis. Necropsy confirmed a malignant, melanotic melanoma with pulmonary and hepatic metastases. Histopathologically, the primary tumor and the metastases were composed of epitheloid cells which showed infiltrative growth. The rabbit was diagnosed with metastatic, cutaneous, melanotic melanoma. Melanomas in rabbits can be recognized as highly malignant independent on their pigmentation status. Pulmonary tropism seems to be a distinct feature of this tumor type in rabbits and indicates that a comprehensive diagnostic workup is necessary to avoid anesthesia-related incidents.