A Spontaneous Melanocytic Iris Melanoma in a Rabbit (Oryctolagus cuniculus Linnaeus, 1758).
de Sousa ACFC, Dos Santos WLA, Maia ACS, de Oliveira AVC, Diniz JARA, de Oliveira TES, de Oliveira REM, de Oliveira MF, Braga JFV, Batista JS, Freitas CIA · Veterinary Ophthalmology · 1 March 2026
Iris melanoma should be considered in rabbits with ocular lesions; enucleation provides effective treatment.
This case report documents the first confirmed spontaneous melanocytic iris melanoma in a domestic rabbit in Brazil's semiarid region. A 2-year-old female rabbit presented with ocular hemorrhage and rupture in the right eye. Histopathological examination revealed a moderately cellular, unencapsulated neoplasm composed of spindle and anaplastic melanocytic cells with brown pigmentation and 12 mitotic figures per 2.37 mm². Immunohistochemical analysis using melanoma cocktail markers (HMB-45, Melan-A/MART-1, and Tyrosinase) confirmed melanoma diagnosis, with Ki-67 showing 38% nuclear proliferation index indicating significant malignant potential. Transpalpebral enucleation was performed as definitive treatment with favorable prognosis. The case emphasizes the critical importance of including iris melanoma in differential diagnoses for ocular lesions in rabbits, a previously undocumented condition in this species within this geographic region.
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