In vitro Epstein-Barr virus infection model of rabbit lymphocytes from peripheral blood or spleen

Most humans become lifelong carriers of Epstein-Barr virus (EBV) by adulthood. Primary EBV infection in adolescents causes infectious mononucleosis. EBV infection is associated with various diseases, neoplasms and hematological disorders. Recently, we reported that EBV can infect rabbits by intravenous, intranasal and/or peroral inoculation, which caused primary EBV infection in rabbits with heterogeneous host reactions. Some rabbits showed chronic and lifelong EBV infection with hemophagocytosis. In this study, to reveal detailed mechanisms in rabbit EBV infection, an in vitro investigation was performed. We elucidated that: (1) EBV can infect rabbit peripheral blood mononuclear cells and splenic lymphocytes in vitro, because EBV gene expressions were confirmed. (2) It is highly likely that the B cell is the main target cell of rabbit EBV infection and is immortalized similar to humans. (3) CD8+ T cells increased in the rabbit in vivo model after EBV inoculation, whereas an increase of B cells occurred after their transient decrease. These data suggest that EBV-infected B cells were proliferated, while CD8+ T cells increased to recognize and kill them. This system may explain the paths of rabbit EBV infection and host reaction, simulating human EBV infection. In vitro studies will be helpful to reveal the pathogenesis of rabbit EBV infection and EBV-associated diseases.

Two cases of primary small cell carcinoma of the stomach

We report 2 cases of small cell carcinoma (SmCC) of the stomach with distant metastasis that were treated with the same chemotherapeutic regimens as used to treat small cell lung cancer. Although the mean survival of patients with SmCC of the stomach is reported to be only 7 months, our patients survived for 15 and 14 months, respectively. In our experience, these chemotherapeutic regimens might provide a survival benefit for patients with SmCC of the stomach, although they demonstrated no remarkable antitumor effects.

Extranodal CD20-positive peripheral T-cell lymphoma presenting with adrenal and testicular masses

We report a case of extranodal CD20-positive peripheral T-cell lymphoma (PTCL). A 59-year-old man was admitted because of a right testicular mass in April 2006. CT scan revealed bilateral adrenal masses and he underwent right orchiectomy. The enlarged testis showed diffuse infiltration of large CD20-positive lymphocytes with slight CD3-positive cells. These cells were negative for CD10 and showed a high MIB-1 index. The pathological diagnosis was diffuse large B-cell lymphoma. He received R-CHOP, but developed brain involvement. He received whole brain radiotherapy following high-dose methotrexate, but he died of disease progression in August 2007. At autopsy, lymphoma cells were definitely positive for CD3 and negative for CD20. Monoclonal TCR gamma gene rearrangement was detected in the brain specimen without IgH rearrangement by PCR. The testicular tumor also showed the same clonal bands. Immunohistochemical re-evaluation of the testis showed CD20+, CD79a-, PAX5-, MUM1-, CD3 p+, CD5 p+, CD4-, CD8-, CD7 p+, granzyme B+, and TIA1+. Based on the clinical course and immunohistology, we finally diagnosed this case as extranodal PTCL-nos (not otherwise specified) with aberrant CD20 expression, which is extremely rare. The detection of gene rearrangement, plural immunohistochemical markers and knowledge of the possibility of CD20+ PTCL-nos are necessary for such cases.

Endoscopic mucosal resection of primary anorectal malignant melanoma: a case report

Anorectal melanoma is a rare malignant tumor with a poor prognosis. However, several studies have reported cases of long-term survival. In this report, we present a patient with anorectal melanoma who has survived for 9 years after endoscopic mucosal resection. An 85-year-old man was referred to our hospital for further examination and treatment of an anal tumor 2 cm in size. Endoscopic ultrasonography revealed that the depth of tumor invasion was confined to the submucosal layer. Endoscopic mucosal resection was performed, and the tumor was diagnosed as a malignant melanoma. The patient was followed without any additional treatment, which was per his wishes. Although melanoma recurred 4 times thereafter, endoscopic mucosal resection was performed for each recurrent lesion. Thus, he has been alive for 9 years since the first endoscopic mucosal resection without distant metastases. If the depth of tumor invasion is shallow, endoscopic mucosal resection is a useful option among other therapeutic modalities.