Human Herpesvirus‐8: A Useful Marker for Distinguishing Kaposi Sarcoma and Kaposi Sarcoma‐like Pyogenic Granuloma

Abstract

Kaposi’s sarcoma (KS) is a vascular neoplasm associated with human herpesvirus‐8 (HHV‐8) infection. On occasion, KS may histologically mimic pyogenic granulomas (PG), a common benign vascular tumor of the skin. Using immunoperoxidase stains, we examined 28 PG and 4 PG‐like KS for HHV‐8 to determine the specificity of positive staining in this setting. All PG‐like KS demonstrated nuclear staining for HHV‐8. No staining was identified in any of the PG. Furthermore, histologic criteria often used to differentiate between these two entities were not helpful in difficult cases. The only distinguishing features were the presence/absence of HHV‐8 staining and, in some cases, clinical history. The presence of HHV‐8 nuclear staining appears to be a specific marker for KS when comparing PG and PG‐like KS. Given the lack of distinguishing morphologic criteria, we suggest performing immunoperoxidase stains for HHV‐8 on any PG occurring in a clinically atypical setting.