Clinical and immunological studies of 49 cases of various types of intercellular IgA dermatosis and 13 cases of classical subcorneal pustular dermatosis examined at Kurume University.
BACKGROUND
Intercellular IgA dermatosis (IAD) is a subset of autoimmune bullous disease exclusively with IgA antikeratinocyte cell-surface antibodies. The classification and pathogenesis of this condition are still obscure.


OBJECTIVE
To classify IAD and study its pathogenesis.


METHODS
From our cohort of 5402 cases of autoimmune bullous disease, we selected 49 cases of various types of intercellular IgA dermatosis (IAD) and 13 cases of classical subcorneal pustular dermatosis (SPD), for which sera and information were available. We studied these cases clinically and immunologically.


RESULTS
There were 17 SPD-type IAD, 12 intraepidermal neutrophilic IgA dermatosis (IEN)-type IAD, two IgA-pemphigus vegetans, four IgA-pemphigus foliaceus, six IgA-pemphigus vulgaris and eight unclassified IAD cases. There was no sex predominance, and the average age at disease onset was 45·9 years. Clinically, bullous and pustular skin lesions developed on various sites, particularly intertriginous areas. Histopathology showed intraepidermal blisters or pustules at the upper epidermis in the SPD-type and at the midepidermis in the IEN-type. Immunological studies revealed that direct immunofluorescence, indirect immunofluorescence of normal human skin and enzyme-linked immunosorbent assays (ELISAs) of recombinant proteins of desmogleins and desmocollins frequently showed positive results, although no antigens were detected in many cases. All cases of classical SPD, which showed no positive immunological results, were indistinguishable clinically and histopathologically from SPD-type IAD.


CONCLUSIONS
The present study of the largest cohort of cases of IAD showed that the major subtypes are SPD and IEN, and that the combination of indirect immunofluorescence and ELISAs of desmogleins and desmocollins, in addition to direct immunofluorescence, was useful for the diagnosis of IAD and its subtypes.
Department of Dermatology, Kurume University School of Medicine, and Kurume University Institute of Cutaneous Cell Biology, 67 Asahimachi, Kurume, Fukuoka, 830-0011, Japan.
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http://orcid.org/0000-0002-0144-3255
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Hashimoto
Department of Dermatology, Kurume University School of Medicine, and Kurume University Institute of Cutaneous Cell Biology, 67 Asahimachi, Kurume, Fukuoka, 830-0011, Japan.
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K
Teye
Department of Dermatology, Kurume University School of Medicine, and Kurume University Institute of Cutaneous Cell Biology, 67 Asahimachi, Kurume, Fukuoka, 830-0011, Japan.
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Ishii
D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001327:Autoimmune Diseases / Q000188:drug therapy / Q000276:immunology* / Q000473:pathology; D015331:Cohort Studies; D003622:Dapsone / Q000627:therapeutic use; D003879:Dermatologic Agents / Q000627:therapeutic use; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D007070:Immunoglobulin A; D008297:Male; D008875:Middle Aged; D008911:Minocycline / Q000627:therapeutic use; D012872:Skin Diseases, Vesiculobullous / Q000188:drug therapy / Q000276:immunology* / Q000473:pathology
D000900:Anti-Bacterial Agents; D003879:Dermatologic Agents; D007070:Immunoglobulin A; D003622:Dapsone; D008911:Minocycline