Detection of herpes simplex virus genomic DNA in various subsets of Erythema multiforme by polymerase chain reaction

The wide variation in the detection of herpes simplex virus (HSV) DNA (36-75%) by polymerase chain reaction (PCR) in erythema multiforme (EM) may be partly attributed to differences in case selection in terms of subsets of EM studied.

To determine the frequencies of detection of HSV DNA in specific subsets of EM.

Nested PCR was used to detect HSV DNA in skin biopsies with histologically proven EM.

PCR was performed on skin biopsies from 63 patients with EM. HSV DNA was detected in 3/11 (27.2%) of single-episode HSV-associated EM (HAEM), 6/10 (60%) of recurrent HAEM, 1/4 (25%) of single-episode idiopathic EM and 6/12 (50%) of recurrent idiopathic EM. HSV DNA was not detected in atypical EM (0/11), suspected drug-induced EM (0/9) or Stevens-Johnson syndrome (0/6).

The overall PCR positive rates of HAEM (42.9%) and idiopathic EM (43.8%) were comparable suggesting that idiopathic EM is likely to be related to a subclinical HSV infection.