The "Guidelines for the management of dermatomycosis" of the Japanese Dermatological Association were first published in Japanese in 2009 and the Guidelines Committee of the Japanese Dermatological Association revised it in 2019. The first guidelines was prepared according to the opinions of the Guidelines Committee members and it was of educational value. The revised version is composed of introductory descriptions of the disease concepts, diagnosis, medical mycology and recent advances in treatment, along with clinical questions (CQ), which is intended to help in general practice for dermatologists. The CQ are limited to those involved in therapy but include some of the recently launched antifungal agents. The level of evidence and the degree of recommendation for each item were reviewed by the committee based on clinical studies published by 2018. For rare dermatomycoses, recommendations by the committee are described in the guidelines. In this field, there are still few good quality studies on treatment. Periodic revision in line with new evidence is necessary.

Fungal diseases in immunocompromised hosts pose significant threats to their prognoses. An accurate diagnosis and identification of the fungal pathogens causing the infection are critical to determine the proper therapeutic interventions, but these are often not achieved, due to difficulties with isolation and morphological identification. In an effort to ultimately carry out the simultaneous detection of all human pathogenic microbes, we developed a simple system to identify 26 clinically important fungi by using a combination of PCR amplification and DNA microarray assay (designated PCR-DM), in which PCR-amplified DNA from the internal transcribed spacer region of the rRNA gene was hybridized to a DNA microarray fabricated with species-specific probes sets using the Bubble Jet technology. PCR-DM reliably identified all 26 reference strains; hence, we applied it to cases of onychomycosis, taking advantage of the accessibility of tissue from skin. PCR-DM detected fungal DNA and identified pathogens in 92% of 106 microscopy-confirmed onychomycosis specimens. In contrast, culture was successful for only 36 specimens (34%), 3 of which had results inconsistent with the results of PCR-DM, but sequence analysis of the isolates proved that the PCR-DM result was correct. Thus, PCR-DM provides a powerful method to identify pathogenic fungi with high sensitivity and speed directly from tissue specimens, and this concept could be applied to other fungal or nonfungal infectious human diseases in less accessible anatomical sites.

We evaluated the efficacy of efinaconazole 10% topical solution in long‐term use, for up to 72 weeks, for onychomycosis, including severe cases. Among 605 participants, 219 patients diagnosed as having onychomycosis were evaluated for the efficacy of efinaconazole. The treatment success rate (<10% clinical involvement of the target toenail) at the final assessment time point was 56.6%, the complete cure rate was 31.1% and the mycological cure rate was 61.6%, all of which increased over time, demonstrating that continuous application contributed to the improvement of cure rate. Even in severe cases, reduction of the affected nail area was observed, showing the potential efficacy of the treatment. Responses to a quality of life questionnaire among patients with onychomycosis, OnyCOE‐t, suggested that efinaconazole treatment improved the patients’ quality of life. The incidence of adverse drug reaction in the patients eligible for the assessment was 6.3%, and this developed only in the administration site in all cases. No systemic adverse event was observed. In addition, no increase in the incidence of adverse drug reaction due to long‐term use was found. Efinaconazole therapy was proved to exhibit excellent balance between efficacy and safety, and thus may serve as a useful treatment option for onychomycosis.