Backgrounds: Kaposi sarcoma is a low-grade vascular tumor with the uniform expression of latent nuclear antigen-1 of the human herpes virus 8 (HHV-8). Differentiation of Kaposi sarcoma from other benign and malignant vascular or non-vascular spindle cell lesions is sometimes a manner of challenge. Thus, the expression of human herpes virus 8 in a fixed specimen would be diagnostically useful. This study aimed at immunohistochemical detection of human herpes virus-8 in cutaneous vascular lesions.
Methods: This cross-sectional study was conducted on 46 cases of cutaneous vascular lesions including six cases of Kaposi Sarcoma, twenty-five cases of Pyogenic Granuloma, four cases of Angiolymphoid Hyperplasia with Eosinophilia, three cases of Masson Tumor, two cases of Arteriovenous Hemangioma, two cases of Sclerosing Hemangioma, three cases of Angiofibroma, and one case of Lymphangioma. After histologic confirmation, immunohistochemistry was done on sections of paraffin-embedded tissue with mouse anti-HHV-8 antibody.
Results: Of 46 patients, 27 (58.7%) were male and 19 (41.3%) were female, and the mean age was 46.36±17.48 years. All 6 Kaposi sarcoma cases showed strong, nuclear staining for HHV-8 (100%). All 6 patients with HHV-8 positive results were older than 60 years.  Sarcoma cases included four (66.7%) resection specimens from the soft tissues of the leg and two (33.3%) resection specimens from the soft tissues of the hand.
Conclusions: The high sensitivity and specificity of the immunohistochemical method for detecting HHV-8 in skin lesions, especially Kaposi sarcoma, makes it a reliable and cost-effective tool to differentiate Kaposi sarcoma from other vascular and non-vascular spindle cell lesions.