Dermal fibroma in a goldfish: Imunohistochemistry and polymerase chain reaction

Abstract

Naturally occuring case of tumor was identified in dermal of a goldfish. Grossly, this mass was found on the right dorsal part of the body, white and glossy, firm in consistency, and consisting of variable-sized distinct lobules with narrow hemorhagic streaks. Histopathologically was composed of wavy spindle shaped cells with long cytoplasmic processes.They have low cellularity, had elongated or big nuclei with indistinct nucleoli. In the intercelular spaces, mild production of collagen and reticular fibers were fOund. The neoplastic cells were negative immunoreactivities tor vimentin and S100 protein. Polymerase chain reaction/PCRs results showed that the mass was positive for Carp !3-acm. Since we used fish genome from a Japanese goldfish as negative control on PCRs it must be consider that the neoplasm is not retrpvirus-free. These findings suggest the diagnosis of tumor was a dermal fibroma and may associate with walleye retrovirus (WRV).