Lymphoma in a Japanese Killifish

Abstract

A lymphoma was found in a Japanese killifish (medaka), Oryzias latipes. The tumor mass was detected in the area adjacent to the left operculum. Lymphoid cells were observed in the dermis, gill, skeletal muscle, thyroid gland, kidney and thymic region. The thymus was considered the primary site because the tumor mass was located mainly at the thymic region, and tumor cells showed massive proliferation in the thymic region.