Erythrophoromas in Colored Crucian Carp, Carassius auratus

Chromatophoromas, cutaneous pigment cell tumors that originate from skin dermochromatophores of fish, amphibians, and reptiles are rarely reported. The four basic pigment cell types found in poikilothermic vertebrates are melanomas (melanophoromas), iridophoromas, xanthophoroma, and erythrophoromas. In the present study, we diagnosed spontaneous lesions in the skin of a group of ornamental colored crucian carp, Carassius auratus, from an artificial ornamental fish pond located in Southeastern China. Necropsy, paraffin section, and hematoxylin-eosin staining methods were used to evaluate the neoplasm. Histological changes were observed and photographed using a Nikon microscope image system. The results showed oval nodular masses observed on the various parts of the body including flank, caudal peduncle, and tail. Histologically, neoplastic stromata were composed of bundles of compact parallel arrays cells. Dendric or spindle-shaped erythrophoroma cells were arranged as sheets or clusters with interlacing connective tissue. Congested capillaries and focal areas of hemorrhage were interspersed through the tissue. The tumor foci were infiltrated with neoplastic cells, inflammation cells, and necrotic tissue cells. Some olive to red intracytoplasmic pigment with polarized light could be seen on many parts of the erythrophoroma tissue. From the gross and histological pathology, we could conclude that the colored crucian carp suffered erythrophoromas. Further study is needed to confirm the etiology of this case.