title: Spontaneous Malignant T Cell Lymphoma in a Young Male Common Marmoset (Callithrix jacchus).
abstract: We histopathologically and immunohistochemically investigated a case of malignant lymphoma that spontaneously developed in a male common marmoset at two years of age. Beginning at two years four months of age, the animal had an enlargement of the submandibular and inguinal lymph nodes, small subcutaneous nodules near the right breast and an approximately fivefold increase in peripheral lymphocyte count compared with the previous examination value. The postmortem findings at two years eight months of age showed lymphadenopathy with enlargement of the thymus and spleen. Small- to intermediate-sized neoplastic lymphocytes had diffusely proliferated in the enlarged nodes. The neoplastic cells were pleomorphic and had irregularly shaped nuclei. The nuclear chromatin staining revealed hyperchromatism in the small-sized cells, and the intermediate-sized cells exhibited vesicular staining. An immunohistochemical examination indicated that the neoplastic lymphocytes were positive for CD3 and negative for CD20, thus suggesting that they had originated from T cells. In addition, the proliferation of high endothelial venules and reactive epithelioid histiocytes was observed. Scattered tingible body-laden macrophages were infrequently detected. Neoplastic lymphocytes were also observed in the thymus, spleen, heart, lungs, liver, kidneys, adrenal glands and femoral and sternal bone marrow. This malignant lymphoma in a young male common marmoset was considered to fit the category of "peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS)" according to the new WHO system of classification.
authors.affiliation: Toxicological Research Laboratories, Kyowa Hakko Kirin Co., Ltd., 1188 Shimotogari, Nagaizumi-cho, Sunto-gun, Shizuoka 411-8731, Japan.
authors.forename: Itaru
authors.initials: I
authors.lastname: Yamaguchi
authors.forename: Kensuke
authors.initials: K
authors.lastname: Myojo
authors.forename: Hiroko
authors.initials: H
authors.lastname: Sanada
authors.forename: Eri
authors.initials: E
authors.lastname: Sudo
authors.forename: Sayaka
authors.initials: S
authors.lastname: Ootsuka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Okumura
authors.forename: Atsuko
authors.initials: A
authors.lastname: Takami
authors.forename: Tomomi
authors.initials: T
authors.lastname: Yoneshige
authors.forename: Yui
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Minami
authors.initials: M
authors.lastname: Imaizumi
authors.forename: Chie
authors.initials: C
authors.lastname: Takada
authors.forename: Naoya
authors.initials: N
authors.lastname: Kimoto
authors.forename: Koji
authors.initials: K
authors.lastname: Saeki
authors.forename: Katsumi
authors.initials: K
authors.lastname: Takaba
keywords: T cell; WHO system of classification; common marmoset; malignant lymphoma