Herpes gestationis: immunopathological and ultrastructural studies.

Eleven patients with the clinical picture of herpes gestationis were investigated. Biopsies were taken from involved and uninvolved areas of skin and the immunopathological and microscopic changes studied. Direct immunofluorescence showed a deposition of C3 and/or IgG at the basement membrane zone in the involved skin of nine patients and the uninvolved skin of five. Immuno-electron microscopy using a multistep peroxidase antiperoxidase method revealed the in vivo deposition of IgG at the basal plasma cell membrane that extended into the lamina lucida. Light microscopy of urticarial and vesicular lesions showed a marked oedema of the papillary dermis with an inflammatory cell infiltrate that was mainly perivascular. There was spongiosis of the epidermis with oedema and necrosis of the basal cells and in several specimens sub-epidermal clefts with bulla formation. Electron microscopy confirmed the marked degenerative and necrotic changes of the basal cells in the involved areas of skin.