We report a unique case of a Japanese woman with herpetiform
pemphigus (HP) who had
IgG autoantibodies reactive with nondesmosomal sites of keratinocytes and presented characteristic transmission electron microscopic (TEM) findings of various-sized vacuoles in keratinocytes without
acantholysis. The patient presented with pruritic annular oedematous
erythemas with small
blisters lining the margins on the trunk and extremities. Histopathological examinations showed intraepidermal
blisters with prominent infiltrations of eosinophils. Direct and indirect immunofluorescence tests revealed the presence of in vivo bound and circulating
IgG autoantibodies to the keratinocyte cell surfaces. However,
enzyme-linked
immunosorbent assays for
desmoglein (Dsg) 1, Dsg3 and
desmocollins 1-3 showed negative results. Immunoblotting using the full-length human Dsg1
recombinant protein showed a positive band. TEM examination showed various-sized vacuoles squashing the nuclei in many keratinocytes, resulting in
rupture of the cells. Immunoelectron microscopic examination revealed
IgG deposition over the entire keratinocyte cell surfaces, which spared the desmosomes.
IgG antibodies were also present on the inside walls of the vacuoles around the nuclei of keratinocytes and on the cell surfaces of infiltrating eosinophils. This patient also had marked
eosinophilia and high levels of
thymus and activation-regulated chemokine and
interleukin-5 in the serum. These results indicated a novel
autoantigen on the nondesmosomal keratinocyte cell surfaces and the pathogenesis of bullous spongiotic change with
inflammation in HP.