Chronic idiopathic erythroderma of elderly men is an independent entity that has a distinct TARC/IgE profile from adult atopic dermatitis.

BACKGROUND: Although there are several diseases that cause erythroderma, patients are often encountered with erythroderma of unknown cause which persists for a long time. The aim of this study was to characterize this chronic idiopathic erythroderma (CIE).

METHODS: Adult patients with CIE, atopic dermatitis (AD), psoriatic erythroderma (PsE), or generalized drug eruption (DE), who visited Fukuoka University Hospital Dermatology Department from 2010 to 2015, were enrolled. Their clinical and laboratory data were extracted from the patient database. CIE was defined as erythroderma without any apparent cause and lasting more than 3 months.

RESULTS: Twenty-three CIE, 82 AD, 39 psoriatic erythroderma, and 99 drug eruption cases were enrolled. The mean age of CIE patients was 74.7 ± 8.8, and the male : female ratio was 21 : 2. Laboratory data for CIE and AD were similar, but serum levels of thymus and activation-regulated chemokine (TARC), a T-helper (Th) 2 cytokine, in the CIE group were significantly more elevated than in the AD group. Conversely, serum immunoglobulin (Ig) E levels were significantly lower in CIE patients compared with the atopic dermatitis group, and the ROC curve of the TARC/IgE ratio (7.24) provided efficient differentiation of the CIE group from AD patients. About PsE and DE, significant elevation of C-reactive protein was observed. Aspartate aminotransferase and alanine aminotransferase were also elevated in DE.

CONCLUSIONS: Chronic idiopathic erythroderma is an independent condition which is likely to occur in elderly men. Immunity is shifted to the Th2 type in CIE; however, the mechanism may differ from that of atopic dermatitis.