Background: The diagnostic distinction of atypical vascular lesion or angiomatoid/hemosiderotic dermatofibroma and Kaposi's sarcoma can be difficult, especially in AIDS patients. Given the strong association between human herpes virus 8 (HHV8) and Kaposi's sarcoma, this study attempts to determine if HHV8 RNA detection by reverse transcription (RT) in situ polymerase chain reaction (PCR) could help in differentiating these entities.
Methods: Twenty-three Kaposi's sarcoma cases, 13 dermatofibromas, including 7 angiomatoid or hemosiderotic variants and eight atypical vascular lesions were tested for HHV8 by RT in situ PCR; five of the patients in the latter two groups were known to have AIDS.
Results: HHV8 RNA was detected in each of the 23 cases considered on histologic grounds to represent Kaposi's sarcoma; viral RNA and DNA localized to the majority of the endothelial and stromal spindle cells. None of the cases of dermatofibroma were HHV8 positive, whereas two of the atypical vascular lesions were viral positive, leading to a final diagnosis of Kaposi's sarcoma.
Conclusions: RT in situ PCR for HHV8 RNA is a useful tool in the differential diagnosis between Kaposi's sarcoma and its mimics.