Background: Onychopapilloma is a benign neoplasm of nail unit commonly presenting as longitudinal chromonychia with occasional splinter hemorrhages or distal subungal keratosis. Pathologically, onychopapilloma shows papillomatous nail bed and distal matrix with layers of hyperkeratosis or matrix metaplasia.

Background: Recently lasers are useful treatment for acne scars, but they also have side effects like postinflammatory hyperpigmentation or postinflammatory erythema. Some types of acne scars are resistant to laser treatment.

Background: Radiodermatitis, a side effect of radiotherapy, presents as erythema, desquamation, skin necrosis, or ulceration. Photobiomodulation therapy (PBMT) has been applied in diverse clinical fields with effects of reducing inflammation, acceleration of wound healing, and pain alleviation.

Background: Cutaneous lymphomas have different clinical behaviors and prognosis with other lymphomas. The classification of cutaneous lymphoma has constantly been revised based on tumor cell biology and diagnostic techniques and WHO-EORTC published an updated classification in 2018.

Background: Cutaneous metastases (CM) indicate advanced disease so it is important for planning. Also knowing the characteristics of the disease and survival rate (SR) is helpful.

Background The influence of airborne particulate matter (PM) on skin has primarily been studied in patients with skin diseases such as atopic dermatitis. Recently, the effect of PM on healthy human skin has gained attention. Objective To evaluate the relationship between PM concentration and objective skin changes in healthy subjects. Methods This prospective study enrolled 25 healthy volunteers without any skin disease. Data regarding daily meteorological parameters and air pollution were collected during a high-PM period and a low-PM period for 14 days. Environmental and lifestyle factors that might influence skin conditions of subjects were also collected during the study period. Biophysical parameters of the skin such as transepidermal water loss (TEWL), hydration, erythema index, and melanin index were measured. Pores, wrinkles, sebum, and skin tone were evaluated using a facial analysis system. Results Mean TEWL value during the high-PM period was significantly higher than that during the low-PM period (10.16 g/m2/h vs. 5.99 g/m2/h; p=0.0005). Mean erythema index was significantly higher in the high-PM period than that in the low-PM period (4.3 vs. 3.42; p=0.038). For facial analysis system indices, uniformity of skin tone was higher in the low-PM period than that in the high-PM period (p<0.0001). In addition, with increasing PM10 and PM2.5, TEWL also showed increase when other environmental components were constant (regression coefficient [RC]=0.1529, p<0.0001 for PM10; RC=0.2055, p=0.0153 for PM2.5). Conclusion Increased PM concentrations may contribute to disturbed barrier function, increased facial erythema, and uneven skin tone even in healthy human skin.

Background: Single cell RNAseq (scRNAseq) has been broadening our understanding of transcriptome profiles of normal and pathologic human skin. However, loss of spatial information related to tissue dissociation has been a hurdle of the interpretation of scRNAseq data.

Programmed death 1 (PD‐1)/programmed death ligand 1 (PD‐L1) inhibitors have demonstrated their efficacy in the treatment of various malignancies. Despite their benefits, their immunomodulatory activities can cause unpredictable cutaneous adverse events (CAE). This study aimed to identify characteristics of CAE in patients treated with PD‐1/PD‐L1 inhibitors through the medical records, photographs, and pathology reports. Fifty CAE occurred in 47 (2.75%) of 1711 patients treated with PD‐1/PD‐L1 inhibitors. Pruritic, psoriasiform, urticarial, and acneiform eruptions were the four most common types. Melanoma patients showed CAE more frequently than other malignancies. Acneiform eruption occurred more often at ages under 60 years. Urticarial eruption appeared earlier, while keratoacanthoma appeared later after immunotherapy. The overall survival times were not significantly different between the two groups with and without CAE by Kaplan–Meier analysis (p = 0.055). Studies on CAE may provide more information to understand these drugs and to help manage the patients.

To the Editor: There have been few studies examining mutational backgrounds for acral melanoma (AM) and different aspects of genetic alterations between nail apparatus melanoma (NAM) and non-nail acral melanoma (NNAM).1Lee M. Yoon J. Chung Y.J. et al.Whole-exome sequencing reveals differences between nail apparatus melanoma and acral melanoma.J Am Acad Dermatol. 2018; 79: 559-561.e551Abstract Full Text Full Text PDF PubMed Scopus (5) Google Scholar, 2Hayward N.K. Wilmott J.S. Waddell N. et al.Whole-genome landscapes of major melanoma subtypes.Nature. 2017; 545: 175-180Crossref PubMed Scopus (537) Google Scholar, 3Siroy A.E. Boland G.M. Milton D.R. et al.Beyond BRAF(V600): clinical mutation panel testing by next-generation sequencing in advanced melanoma.J Invest Dermatol. 2015; 135: 508-515Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar The aim of this study was to uncover previously unidentified novel mutations in patients with AM and compare genetic mutational profiles between NAM and NNAM. We carried out paired whole-exome sequencing (WES) of saliva and affected tissue samples, collected from Korean patients with AM pathologically confirmed at Samsung Medical Center (Seoul, Korea) from September 2016 to March 2019, as described in our previous study.4Lim Y. Shin H.T. Choi Y. Lee D.Y. Evolutionary processes of melanomas from giant congenital melanocytic nevi.Pigment Cell Melanoma Res. 2020; 33: 318-325Crossref PubMed Scopus (6) Google Scholar Detailed methods are presented in Supplemental Appendix 1 (available via Mendeley at https://doi.org/10.17632/9kbh6p3cft.2). The clinical details of patients included in this study are shown in Supplemental Appendix 2 (available via Mendeley at https://doi.org/10.17632/9kbh6p3cft.2). Among the 31 AMs tested, 6 were melanoma in situ; 24 patients had NNAM, and 7 patients had NAM. Through WES, single nucleotide variations (SNVs) and small insertions/deletions were identified (Supplemental Appendix 3; available via Mendeley at https://doi.org/10.17632/9kbh6p3cft.2). In NNAM, mutations were identified in BRAF (16.67%), NRAS (12.50%), and KIT (8.33%). In NAM, only 1 patient (14.29%) showed an alteration in BRAF, and no patients showed NRAS or KIT mutations. Fifty-three genes were repeatedly detected (≥2 times) as having somatic mutations in AMs (Fig 1). Of them, 11 genes have been previously reported to be associated with melanoma (Supplemental Appendix 4; available via Mendeley at https://doi.org/10.17632/9kbh6p3cft.2). Among SNVs, mutations in 25 genes were predicted to be significantly deleterious5Choi J.H. Kim Y.B. Ahn J.M. et al.Identification of genomic aberrations associated with lymph node metastasis in diffuse-type gastric cancer.Exp Mol Med. 2018; 50: 6Crossref PubMed Scopus (13) Google Scholar in developing melanomas. Fisher's exact test showed that CES1, CSMD3, EHMT1, and MAGI1 did not appear in NNAM but were distinct mutations in NAM (P = .045). We also identified genomic regions affected by copy number alterations (CNAs) (Fig 2). The CNA analysis was based on WES data. CNAs were relatively infrequent in NAMs but common in NNAMs.Fig 2Heat map of copy number alterations detected in NNAM and nail apparatus melanoma NAM samples of patients. ID, Identification; NAM, nail apparatus melanoma; NNAM, nonnail acral melanoma.View Large Image Figure ViewerDownload Hi-res image Download (PPT) In the present study, the frequencies of BRAF and NRAS mutations in patients with AM, especially in NAM, were lower than those in a previous study on cutaneous melanoma patients.3Siroy A.E. Boland G.M. Milton D.R. et al.Beyond BRAF(V600): clinical mutation panel testing by next-generation sequencing in advanced melanoma.J Invest Dermatol. 2015; 135: 508-515Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar This suggests that NAM might require genetic alterations other than BRAF and NRAS. Hayward et al2Hayward N.K. Wilmott J.S. Waddell N. et al.Whole-genome landscapes of major melanoma subtypes.Nature. 2017; 545: 175-180Crossref PubMed Scopus (537) Google Scholar reported, based on whole genome sequencing, that the frequencies of SNVs and insertions/deletions were lower but the frequency of structural variants was higher in AM and mucosal melanoma than in cutaneous melanoma. The present study is limited by the small number of cases and by using WES rather than whole genome sequencing. Based on the results of analysis of significantly deleterious mutations, CSMD3 and EHMT1 might have an important role in the pathogenesis of NAM but not in NNAM. Previously, there have been several reports on the association of these genes with malignancies (Supplemental Appendix 5; available via Mendeley at https://doi.org/10.17632/9kbh6p3cft.2). Because our study used only WES, it is currently difficult to know the potential roles of these genes. Therefore, protein work or interaction analysis through transcript analysis may be helpful in the future. In conclusion, we found possible pathogenic mutations previously unidentified in AM and identified differences between NAM and NNAM. Also, mutations in CSMD3 and EHMT1 could play a distinct oncogenic role in NAM. Further studies are needed to validate this result.

Drug-induced vasculitis is an inflammation of small-sized blood vessel caused by the use of drugs. It accounts for approximately 10% of acute cutaneous vasculitis. Propylthiouracil, hydralazine, and allopurinol have been widely known as causative agents. The most common clinical feature of drug-induced vasculitis is palpable purpura on lower extremities. A 66-year-old Korean female presented with erythematous nodules on upper chest and back. She had been on medication for multiple myeloma. Laboratory results showed neutropenia. After a single injection of filgrastim (recombinant granulocyte colony-stimulating factor), she developed cutaneous lesions with concurrent increase in absolute neutrophil count. A skin biopsy revealed leukocytoclastic vasculitis. After discontinuation of filgrastim injection, her skin lesions disappeared spontaneously.

Non-Langerhans cell histiocytosis (NLCH) is a group of disorders defined by the proliferation of histiocytes other than the Langerhans cell. Because of a close relationship within this group of disorders, categorizing a patient under a single disease entity is difficult.1 Likewise, substantial clinicopathologic similarities exist among adult xanthogranuloma (AXG), xanthoma disseminatum (XD), and Erdheim-Chester disease (ECD). We report a case of generalized xanthogranuloma with systemic involvement showing overlapping features of adult-onset AXG, XD and ECD.