Human Herpesvirus-8 (HHV-8) and its Correlation with Oral Kaposi’s Sarcoma Progression

1Health Sciences Department México City, Universidad Autónoma Metropolitana-Xochimilco (UAM-X), México-D.F. 2Oral Pathology Laboratory, School of Dentistry of Piracicaba-Unicamp, São Paulo- Brazil. 3School of Dentistry, Universidad Autónoma de Chihuahua, Chihuahua, México.

Objective: The aim of the present study was to identify and quantify the positive HHV-8 and cytomegalovirus (CMV) cells and its association with the histological stages of oral Kaposi´s sarcoma (OKS).

Methods: Retrospective, observational and comparative study. Oral KS cases came from AIDS patients, who attended a referral center for HIV-infected patients in Mexico City. The median age of the 39 OKS male patients included was 30 (range, 23-70) years, 25 (64.1%) were under combined antiretroviral therapy, with a median time of 62.5 (14-369) days. OKS tissue samples retrieved from the files of the Oral Pathology Laboratory, UAM-X, were histologically reviewed and classified in early, intermediate, and late stages. Sections from formalin-fixed paraffin-embedded archival tissue blocks were analyzed by immunohistochemistry using antibodies for HHV-8 (LANA-1) and CMV. The percentage of positive cells for HHV-8 was calculated using a 40x microscope objective. Photomicrographs were taken from five randomly selected fields per case, subsequently transferred to a grid and the number of cells counted. The labelling index of positive cells was calculated for each case. Expression of CMV was considered as negative or positive. Chi-square test and the Wilcoxon-Mann-Whitney rank sum test were applied.

Results: Fourteen OKS cases were mucocutaneous (35.9%); palate was involved in 70.6%. The median CD4+ count was 112 (Q1-Q3, 36.5–166.2) cell/mm3, the median viral load was 2510 (Q1-Q3, 359.7–197500) copies/ml. The percentage of HHV-8 positive cells increased significantly from early/intermediate (15.4±10.4) to late (24.5±15.9) (p≤0.05) stages. Only two cases of late-stage OKS presented infection by CMV; in one of them, CMV inclusion bodies were present in spindle and acinar cells of minor salivary glands.

Conclusions: The role for HHV-8 was confirmed through the progressive increase in the number of positive cells from early/intermediate to late lesions; however, no evidence supported an active role of CMV in the pathogenesis of KS. This work was supported by the State of São Paulo Research Foundation (FAPESP), CNPq (grant #471937/2006-1) and the Universidad Autónoma Metropolitana-Xochimilco.