Genotypic and clinicopathological characterization of Kaposi's sarcoma‐associated herpesvirus infection in Japan

Kaposi's sarcoma‐associated herpesvirus (KSHV) is related causally to Kaposi's sarcoma, primary effusion lymphoma, and a subset of cases of multicentric Castleman's disease. As the numbers of acquired immunodeficiency syndrome (AIDS) patients have increased, KSHV‐associated diseases have also increased in Japan. Sporadic cases of classic Kaposi's sarcoma have also been reported in Japan. In the present study, the clinicopathological characteristics of 75 samples, comprising 68 cases of Kaposi's sarcoma, 5 cases of primary effusion lymphoma, and 5 cases of multicentric Castleman's disease were investigated. All of these cases were positive for KSHV by immunohistochemistry or PCR analysis. All fifty‐two of the AIDS‐associated Kaposi's sarcoma cases were males, whereas 7 of the 13 non‐AIDS‐associated Kaposi's sarcoma cases were females. The mean age of patients with AIDS‐associated Kaposi's sarcoma or primary effusion lymphoma was 46 years, whereas the mean age of patients with non‐AIDS‐associated Kaposi's sarcoma or primary effusion lymphoma was 71.8 and 97.5, respectively. KSHV genotypes were determined based on the sequence of variable region 1 in the K1 gene. Genotypes A and C of KSHV were detected in both AIDS‐ and non‐AIDS‐associated Kaposi's sarcoma. Genotype A was detected more frequently in AIDS‐associated cases than non‐AIDS‐associated cases, suggesting that genotype C is broadly distributed in Japan, and genotype A spreads among AIDS patients. Genotype D was detected only in non‐AIDS‐associated Kaposi's sarcoma. These data confirmed the difference between AIDS‐ and non‐AIDS‐associated KSHV diseases with regard to age of onset, gender, and genotypes in Japan. J. Med. Virol. 82:400–406, 2010. © 2010 Wiley‐Liss, Inc.