Diagnostic Performance of PCR-Based Detection of Human Herpesvirus 8 DNA in Archived Formalin Fixed Paraffin Embedded Biopsy Specimens of Kaposi Sarcoma.

BACKGROUND

Kaposi sarcoma (KS) is a vascular malignancy closely associated with human herpesvirus 8 (HHV-8) infection, and its diagnosis relies on combined clinical, histopathological and molecular assessment. This study aimed to detect HHV-8 DNA in archived formalin fixed paraffin embedded (FFPE) biopsy samples of KS by real time PCR and to evaluate the diagnostic performance of PCR compared with histopathology. Meth ods: In this retrospective cross-sectional study, 98 FFPE biopsy specimens with histopathologically confirmed KS and 30 FFPE biopsy specimens with non-KS vascular lesions were included as the patient and control groups, respectively. HHV-8 DNA was analyzed in all samples using real-time PCR. Diagnostic performance parameters, including sensitivity, specificity, predictive values, and accuracy, were calculated, and agreement with histopathological diagnosis was assessed using Cohen's kappa coefficient.

RESULTS

HHV-8 PCR was positive in 89.8% (88/98) of KS cases and negative in all controls (30/30; 100%). Sensitivity, specificity, positive predictive value, negative predictive value and overall accuracy were 89.8%, 100%, 100%, 75.0% and 92.2%, respectively. Overall agreement between PCR and histopathology was 92.2% with a Cohen's kappa of 0.34 (p < 0.001), indicating fair concordance. PCR positivity rates and cycle threshold values did not differ significantly between histopathological stages, or according to histopathological and immunohistochemical parameters.

CONCLUSIONS

HHV-8 PCR in archived FFPE KS biopsies shows high specificity and good sensitivity and acts as a complementary diagnostic tool with fair agreement with histopathology. It is particularly valuable in diagnostic gray areas but should always be interpreted together with clinical, histopathological and immunohistochemical findings.