The Japanese Journal of Dermatology
Online ISSN : 1346-8146
Print ISSN : 0021-499X
ISSN-L : 0021-499X
Volume 127 , Issue 1
Showing 1-7 articles out of 7 articles from the selected issue
Seminar for Medical Education
Original Articles
  • Shigeruko Iijima, Takahiko Tsunoda
    2017 Volume 127 Issue 1 Pages 23-30
    Published: January 20, 2017
    Released: January 20, 2017

    We report seven cases of contact dermatitis due to benzoyl peroxide (BPO), which occurred after the application of gels containing BPO such as therapeutic agents for pimples (Bepio® gel and Duac® combination gel). None of the patients had any history of atopic dermatitis or had previously used skincare products containing BPO. Patch tests using 1% BPO in petrolatum and the BPO gels revealed that four of the patients were allergic to BPO; in the remaining 3 patients, BPO acted only as an irritant. In the former four patients, the onset of allergic contact dermatitis occurred 9 to 24 days after the initial application of the causative substance, while in the remaining three patients it took only two days to induce irritant contact dermatitis. The clinical findings of the allergic and irritant dermatitis induced by these gels were very similar. For diagnostic purposes, it is essential to confirm the duration of application and the skin reactions induced via patch testing. The frequency of allergic contact dermatitis to BPO was 2.7% at our clinic; thus, dermatologists should be aware of this allergenicity when prescribing BPO gels.

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Case Reports
  • Mai Ishikawa, Etsuko Okada, Keiichiro Ryuzaki
    2017 Volume 127 Issue 1 Pages 31-38
    Published: January 20, 2017
    Released: January 20, 2017

    A 72-year-old Japanese man had a seven month history of ill-defined erythema at the left inguinal region. This erythema had gradually enlarged and formed indurated mass. A skin biopsy from the indurated mass revealed tumor cells with signet ring cells, mainly in dermis. We suspected metastatic adenocarcinoma at first, but no masses were detected elsewhere. A total resection was performed. Histological evaluation of the epidermis revealed typical Paget's cells. Prominent signet ring cells formed nests in the superficial dermis, and marked proliferation of small cells appeared as linear strands and solid masses. Immunohistochemical staining was positive for cytokeratin 7 (CK7), cytokeratin 20 (CK20), and gross cystic disease fluid protein-15 (GCDFP-15). He was finally diagnosed with primary invasive extramammary Paget's disease. Because signet ring cells emerge in secondary Paget's disease, metastatic skin tumors, and primary skin tumors, it is necessary to distinguish primary Paget's disease from the other possibilities. In this diagnostically difficult case, an accurate conclusion was achieved by comprehensive inspection results.

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