Several studies have determined the correlation between programmed cell death protein-1 (PD-1) and chronic plaque psoriasis (CPP). However, limited studies have assessed the association between PD-1 expression and the clinicoprognostic and distinct clinicopathological characteristics of CPP and guttate psoriasis (GP). Twenty-nine patients with skin biopsy-confirmed CPP were recruited at the Asan Medical Center between January 2018 and June 2020, and 33 patients with biopsy-confirmed GP were enrolled between January 2002 and June 2020. The clinicoprognostic and histopathological characteristics were analyzed according to immunohistochemical PD-1 expression in the epidermal or dermal inflammatory infiltrates. The CPP and GP lesions were divided into PD-1-low and PD-1-high groups. The CPP epidermal PD-1-high group had typical histopathological changes and significantly higher psoriasis area and severity index scores (p = 0.014) and disease duration (p = 0.009) than the epidermal PD-1-low group. In patients with GP, compared with the dermal PD-1-high group, the dermal PD-1-low group exhibited significantly higher disease duration (p = 0.002) and relapse rate of plaque psoriasis (p = 0.005) and significantly lower relapse-free survival (p = 0.016). Upregulated epidermal PD-1 expression was correlated with the chronicity and severity of CPP, while downregulated dermal PD-1 expression was correlated with poor prognosis of GP.

Relatively little is known about the clinicopathologic characteristics of solar lentigo, rendering the choice of laser treatment a clinical challenge. This study compared the clinicohistopathologic characteristics of patients with solar lentigo on the face with and without conspicuous inflammation. The medical records were evaluated to determine the clinical and histopathological characteristics. Based on the degree of histopathologically observed inflammation, the patients were divided into two groups, those with inflammatory and non‐inflammatory solar lentigo. The demographic characteristics of patients in the inflammatory (n = 62, 62.6%) and non‐inflammatory groups (n = 37, 37.4%) did not differ significantly. Lesion duration was shorter, and the proportion of patients whose lesions changed within 6 months was higher in the inflammatory than in the non‐inflammatory group. The mean longest lesion diameter was greater in the inflammatory than in the non‐inflammatory group. Histopathologically, epidermis was thicker in the inflammatory than in the non‐inflammatory group. The grade of basal hyperpigmentation was higher in the non‐inflammatory group, whereas telangiectasia was more frequent in the inflammatory group. The treatment response rate was lower in the inflammatory (7/21, 33.3%) than in the non‐inflammatory group (8/10, 80.0%). Optimal laser treatment strategies may differ in these two groups.

Background: Limited clinicopathological and prognostic data are available on hydroa vacciniforme (HV)-like lymphoproliferative diseases (HVLPD). Methods: This systematic review searched HVLPD reports in Medline via PubMed, Embase, Cochrane, and CINAHL databases in October 2020. Results: A total of 393 patients (65 classic HV, 328 severe HV/HV-like T-cell lymphoma [HVLL]) were analyzed. Among severe HV/HVLL cases, 56.0% were Asians, whereas 3.1% were Caucasians. Facial edema, hypersensitivity to mosquito bites, the onset of skin lesion, and percentage of severe HV/HVLL differed significantly by race. Progression to systemic lymphoma was confirmed in 9.4% of HVLPD patients. Death occurred in 39.7% patients with severe HV/HVLL. Facial edema was the only risk factor associated with progression and overall survival. Mortality risk was higher in Latin Americans than in Asians and Caucasians. CD4/CD8 double-negativity was significantly associated with the worst prognosis and increased mortality. Conclusion: HVLPD is a heterogeneous entity with variable clinicopathological features associated with genetic predispositions.

Background: Acral melanoma (AM) shows different genomic profiles based on BRAF status, and the data on the association with BRAF and immune checkpoint molecules are lacking.Objectives: This study aimed to identify the significance of BRAF mutation in AMs, exploring expression patterns of immune checkpoint molecules and transcriptome profiles related to tumour immunity according to BRAF status.Methods: Immunohistochemical (IHC) staining of BRAF, Programmed death‐1 (PD‐1), Lymphocyte‐activation gene‐3 (LAG‐3) and T‐Cell Immunoglobulin and mucin domain‐3 (TIM‐3) was performed on AM tissues. Through spatial transcriptome analysis, the correlation between BRAF expression and immune checkpoint molecule expression was examined. Analysis on differentially expressed genes along with pathway analysis and immune cell deconvolution was performed comparing BRAF‐high and BRAF‐low groups at the mRNA level.Results: In IHC and spatial transcriptome analysis, BRAF positivity was associated with high expression of PD‐1, LAG‐3 and TIM‐3. Among a total of 144 patients, positive IHC results for BRAF (p < 0.01), PD‐1 (p < 0.01), LAG‐3 (p < 0.01) and TIM‐3 (p < 0.01) were significantly associated with histopathologic traits including pathological subtypes, cytomorphology, pagetoid spread and nest formation. In spatial transcriptome analysis, the expression level of LAG‐3 showed a significant association with the expression level of BRAF (p < 0.01). Pathways related to anti‐tumour immunity were significantly downregulated in the BRAF‐high group. In immune cell deconvolution, endothelial cells (p = 0.001), mast cells (p = 0.014) and neutrophils (p = 0.004) were significantly higher in the BRAF‐high group.Conclusions: BRAF mutation in AM is associated with increased expression of immune checkpoint molecules, supporting the use of immunotherapy for BRAF‐mutant AM in clinical practice. Different tumour microenvironments regarding tumour immunity in BRAF‐mutant AM may explain the poor prognosis.