Refining criteria for diagnosis of cutaneous infections caused by herpes viruses through correlation of morphology with molecular pathology

BACKGROUND: Infections of the skin by herpes viruses do not always present themselves in typical fashion. Early diagnosis, however, is crucial for appropriate treatment. Polymerase chain reaction (PCR) allows diagnosis and differential diagnosis of herpes virus infections, but the method is not yet available in large parts of the world, where diagnosis is made based on morphology alone. AIM: To refine criteria for the diagnosis of herpes virus infections of the skin by way of correlation of clinical and histopathologic findings with results of PCR studies. METHODS: We studied 75 clinically diagnosed patients of zoster, varicella, and herpes simplex, to correlate clinical and histopathological findings with results of PCR studies on paraffin embedded biopsy specimens. RESULTS: Clinical suspicion of infection by herpes viruses was confirmed by histopathology in 37% of the cases and by PCR studies in 65% of the cases. Zoster was frequently misdiagnosed as infection with herpes simplex viruses (30%). When diagnostic signs of herpes virus infection were encountered histopathologically, PCR confirmed the diagnosis in 94%. By way of correlation with results of PCR studies, initial lesions of herpes virus infections could be identified to have a distinctive histopathological pattern. Herpetic folliculitis appeared to be a rather common finding in zoster, it occurring in 28% of the cases. CONCLUSION: We conclude that correlation of clinical and histopathological features with results of PCR studies on one and the same paraffin embedded specimen permits identification of characteristic morphologic patterns and helps to refine criteria for diagnosis both clinically and histopathologically.