Liquid nitrogen cryosurgery for a chromatophoroma in a captive largemouth bass (Micropterus salmoides)

Chromatophoromas are a common, pigmented malignant tumor that originates from dermochromatophores normally found in the skin of amphibians, reptiles, and fish. Chromatophoromas are typically locally aggressive and can appear as unsightly exudative masses. Effective treatment options in fish are limited mostly to surgical excision. An alternative approach to traditional surgical excision is liquid nitrogen cryosurgery. An adult (3.63 kg) largemouth bass (Micropterus salmoides), housed in a mixed teleost species tank, presented with a history of inappetence of 14 days duration and 2 visible cutaneous skin lesions. Histopathology revealed the cutaneous skin lesions to be consistent with a chromatophoroma. Cryosurgery was successfully used to remove the diseased tissue, and no evidence of the tumor was identified on follow-up histopathologic examination.