Detection of HSV‐specific DNA in biopsy tissue of patients with erythema multiforme by polymerase chain reaction

Formalin‐fixed paraffin‐embedded skin biopsies of lesions of erythema multiforme (EM) from 32 patients and 13 controls were examined for the presence of herpes simplex virus (HSV) by polymerase chain reaction (PCR) and for histological findings by direct immunofluorescence and staining with haematoxylin and eosin. HSV‐specific DNA was detected in 23 (72%) patients. A history of recurrent skin rash was present in 59% of the PCR‐positive cases, while 55% had had suspected HSV infections. Only two PCR‐positive specimens were found in patients without a history of recurrent rash and/or previous oral lesions. One biopsy was positive for HSV by conventional cell cultures. There was no significant difference in histology between HSV‐related and HSV‐negative cases of EM. In the 13 control specimens [bullous pemphigoid (3), dermatitis herpetiformis (2), lichen planus (1), aphthous ulcer (1), fixed‐drug eruption (1), varicella‐zoster (1), hypereosinophilic syndrome (1), photocontact dermatitis (1), contact dermatitis (1), and cellulitis (1)], no HSV‐DNA was detected.