Background: Eosinophilic cellulitis, also known as Wells' syndrome, is an uncommon skin disease characterized by recurrent pruritic polymorphous plaques or nodules. There is limited knowledge in the Korean literature regarding the clinical characteristics and course of eosinophilic cellulitis.
Objective: To investigate the clinical and histological features of eosinophilic cellulitis in Korean patients.
Methods: In this case series study, we retrospectively reviewed the electronic medical records of patients diagnosed with eosinophilic cellulitis at our institutions from 2004 to 2022. We also analyzed the literature published in dermatology and internal medicine journals in Korea.
Results: A total of 17 patients were included in this study (age, 39.4±21.8 years; 12 male [70.6%]), with an average disease duration of 4.4 months. We identified six clinical variants, with the typical plaque type being the most common (33.3%), followed by the papulonodular type (22.2%). Eosinophilia was observed in 78.6% of patients, and a flame figure, which is a typical histopathological feature of eosinophilic cellulitis, was observed in 52.9% of patients. Systemic and topical steroids and antihistamines were used as first-line treatment with generally favorable results (82.4%), followed by antibiotics (35.3%), cyclosporine (23.5%), and topical calcineurin inhibitors (23.5%). The recurrence rate during the mean follow-up period of 21.8 months was 29.4%.
Conclusion: Eosinophilic cellulitis can present with various clinical manifestations, and flame figures do not appear in all cases; therefore, clinical and histological correlations are critical for accurate diagnosis of patients with eosinophilic cellulitis. (Korean J Dermatol 2023;61(1):1∼12)

Background: Metastatic skin cancers occur when cancer cells metastasize to the skin as the primary cancer progresses, but few studies in Korea have included a large number of patients.
Objective: To analyze the clinicopathological characteristics of metastatic skin cancers originating from solid cancers.
Methods: A total of 191 patients with metastatic skin cancer diagnosed by skin biopsy from April 2004 to December 2021 were retrospectively analyzed. Data on age, sex, duration, symptoms, clinical manifestations, metastatic sites, and histopathological findings were obtained from medical records and photographs.
Results: The mean age of onset was 65.3 years, the male/female ratio was 80:111, and the mean duration was 3.3 months. Most patients were asymptomatic (65.4%), and the most frequent manifestation was nodular lesions (64.4%). Among the 191 metastatic skin cancers, the most common primary cancers were breast cancer (31.9%), lung cancer (25.7%), and melanoma (18.8%). The most common primary cancer in males was lung cancer (52.5%), and that in females was breast cancer (54.1%). The most common sites of metastatic skin cancer were the chest (26.6%), scalp (17.9%), abdomen (10.6%), and back (9.2%). The most common histopathological finding of metastatic skin cancer was adenocarcinoma (53.4%), followed by melanoma (18.8%) and squamous cell carcinoma (14.7%).
Conclusion: We believe that this study will be helpful in diagnosing metastatic skin cancer in patients with a history of cancer or a newly diagnosed primary cancer. (Korean J Dermatol 2023;61(1):13∼21)

Background: Glomus tumors are benign vascular tumors derived from the glomus body, a neuromuscular vascular tissue responsible for regulating the temperature and blood flow of the skin. Ultrasonography (USG) is a useful tool for diagnosing glomus tumors; nevertheless, data on Korean patients with glomus tumors are limited.
Objective: This study aimed to describe USG findings of subungual glomus tumors in Korean patients.
Methods: We retrospectively reviewed the medical records and USG readings of 20 cases of glomus tumors in the nail apparatus diagnosed from January 2015 to December 2021.
Results: Twenty patients were included in this study. Four patients (20.0%) were male and 16 (80.0%) were female. The age of onset ranged from 18∼86 years, with a mean of 45.2 years. USG findings showed hypoechoic echogenicity in all cases. Tumor size ranged from 2.3∼10 mm (mean±standard deviation, 5.5±1.9 mm). The tumor shape observed on USG was oval in 16 cases (80.0%), lobulated in three cases (15.0%), and round in one case (5.0%). Tumor boundaries were well-defined in 18 cases (90.0%) and ill-defined in two cases. Posterior acoustic enhancement and cortical erosion were observed in 19 (95.0%) and 17 cases (85.0%), respectively. Increased vascularity was observed in 19 cases (95.0%).
Conclusion: This study revealed characteristic USG features of glomus tumors. USG is a helpful tool for the diagnosis and management of glomus tumors. (Korean J Dermatol 2023;61(1):22∼28)

Background: Actinic keratosis (AK) is a common precancerous cutaneous lesion. There are various AK treatment methods; however, no specific method is considered superior. Most existing studies on AK treatment are Caucasian-based and include patients with multiple lesions.
Objective: This study aimed to compare the treatment duration, financial costs, and success rates of topically applied 5% 5-fluorouracil (5-FU) solution, 5% imiquimod (IMIQ) cream, and cryosurgery in the treatment of histologically proven single-lesion AK in Korean patients.
Methods: We retrospectively reviewed the medical records of patients with single-lesion AK at a single Korean center from January 2018 to February 2021. Each patient was treated using the three aforementioned local treatments.
Results: The study included 58 patients. Nineteen of 23 (82.6%), 27 of 27 (100%), and eight of eight patients (100%) were successfully treated after topical 5-FU, topical IMIQ, and cryosurgery, respectively. Further analysis on treatment success by subgroup revealed the following: mean number of outpatient visits, 3.78 vs. 4.41 vs. 3.75; mean treatment duration, 5.79 vs. 6.00 vs. 9.38 weeks; and mean total treatment cost, 79,380 vs. 170,023 vs. 173,116 won; for the 5-FU, IMIQ, and cryosurgery subgroups, respectively. The total treatment cost was significantly different among the subgroups (p≤0.001).
Conclusion: Topical IMIQ and cryosurgery were superior in terms of treatment efficacy, but considering its low cost, 5-FU may also be a reasonable option. Hence, an individualized approach to treating localized AK should be taken. (Korean J Dermatol 2023;61(1):29∼35)

Background: Adiponectin is an adipose-derived hormone that plays a role in various metabolic diseases. We previously demonstrated that adiponectin inhibits melanin synthesis through adenosine monophosphate-activated protein kinase (AMPK) activation in melanocytes. However, melanocytes can be affected by neighboring keratinocytes, and the effect of adiponectin on these functional units has not been investigated.
Objective: We investigated the effect of adiponectin on melanogenesis in co-cultured models of normal human melanocytes (NHMs), normal human keratinocytes (NHKs), and human dermal fibroblasts (HDFs), and the effect of adiponectin on melanin content in human skin tissues.
Methods: Quantitative real-time polymerase chain reaction (qPCR) was performed for tyrosinase and microphthalmia-associated transcription factor (MITF). The degree of phosphorylation of AMPK, cAMP response element binding protein (CREB), and AKT was evaluated by western blot assay, and Fontana-Masson staining was performed on cultured human skin tissues.
Results: Adiponectin decreased the melanin content in the co-culture models of NHMs with NHKs, NHMs with HDFs, and NHMs with both NHKs and HDFs. qPCR revealed that both tyrosinase and MITF were decreased after adiponectin treatment in the co-culture system. Following adiponectin treatment, AMPK was activated in all cell groups; however, the phosphorylation of CREB was decreased in HDFs and NHKs. The phosphorylation of AKT was decreased in only NHMs. In the experiment with human skin tissues cultured ex vivo, the densitometric analysis of Fontana-Masson staining revealed that adiponectin treatment reduced the melanin level of ultraviolet-irradiated human skin tissues.
Conclusion: Adiponectin inhibited melanogenesis in both co-culture models and human skin tissues ex vivo. (Korean J Dermatol 2023;61(1):36∼42)

Background: The primary goal of scabies treatment is to eliminate mites; however, but post-scabetic itch persists in many patients. Since long-standing itching can lead to the development of other comorbidities, appropriate interventions are necessary.
Objective: This study aimed to investigate the effects of inappropriate (continuous or prolonged) scabicide use and oral steroids on the duration of pruritus in patients with scabies.
Methods: The duration of pruritus, use of oral corticosteroids, total immunoglobulin E (IgE) levels, specific IgE levels for house dust mites, and eosinophil counts were evaluated. Post-scabetic itch was defined as itching that persisted for more than 3 weeks, although scabies was no longer detected; 208 participants with post-scabetic itch were included.
Results: We recruited 265 participants with confirmatory diagnosis of scabies and 116 with clinical diagnosis. We treated 124 participants with scabicides based on the guidelines, whereas 257 participants were not. The type of scabicide did not affect the duration of pruritus. Scabicide overuse did not shorten the duration of pruritus; however, its prolonged use lengthened the treatment period. Although oral corticosteroids did not shorten the duration of pruritus in the patients, they were effective when the patient had post-scabetic itch. In addition, a positive correlation between the total IgE level and duration of pruritus was observed.
Conclusion: This study investigated the effect of treatment modality on the clinical course of scabies. Our findings suggest that overuse of scabicides might be associated with post-scabetic itch, and short-term use of oral corticosteroids may be effective in reducing its duration. (Korean J Dermatol 2023;61(1):43∼51)

Congenital cutaneous candidiasis (CCC) is a rare disease caused by Candida spp. that occurs within the first six days of life. Its exact pathogenesis remains unclear; however, the suspected pathomechanisms include maternal vulvovaginal candidiasis and ascending infections. A preterm, 1,550-g male infant presented with generalized maculopapules and pustules on his whole body. The patient's mother had undergone cervical cerclage at a gestational age (GA) of 29 weeks due to an incompetent internal os of the cervix. The pregnancy was terminated at GA 37-week because the mother developed chorioamnionitis. We performed a potassium hydroxide microscopic examination, skin biopsy, and fungal culture test on the baby. Microscopic examination of the skin scrapings revealed pseudohyphae with yeasts, and Candida albicans was identified in the culture test. Maternal placental biopsy revealed fungal organisms, and the baby was diagnosed with CCC due to an ascending infection. The skin lesions completely disappeared after intravenous liposomal amphotericin B treatment. (Korean J Dermatol 2023;61(1):52∼56)

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive lymphoma with an overall incidence of 0.04 cases per 100,000 people. BPDCN is a hematopoietic clonal neoplasm that originates from plasmacytoid dendritic cell precursors. A 63-year-old man presented with multiple erythematous nodules over his whole body, including his face, trunk, and both upper and lower extremities that appeared 1 month ago. Skin biopsy showed diffuse dermal infiltration by monomorphic atypical lymphocytes with large, irregular nuclei and scant cytoplasms. Immunohistochemical staining was positive for CD4, CD56, and CD123. The karyotype test showed abnormalities in male chromosomes 47, XY, +8 [2]/46, and XY [25], and mutations in DNMT3A, TET2, SRSF2, and ATRX genes were identified in a next-generation sequencing (NGS)-based acute myeloid leukemia gene panel test. The patient was diagnosed with BPDCN and treated with a KALLA 1406 regimen; however, he died on the 17th day of treatment. (Korean J Dermatol 2023;61(1):57∼61)

Bullous pemphigoid (BP) is a chronic and recurrent bullous disorder that may be associated with the administration of certain drugs. Recently, bullous cutaneous adverse events after immunotherapy (IT) or targeted therapy have been increasingly reported. Here, we report a case of BP in a patient diagnosed with metastatic melanoma after treatment with pembrolizumab, dabrafenib, and trametinib. Histopathological examination showed a subepidermal blister with perivascular lymphocytic and eosinophilic infiltration; the accompanying findings of linear immunoglobulin G and C3 deposition by immunofluorescence microscopy were consistent with BP. Since IT agents may initiate immune dysregulation and pathologic autoantibody production, which are required for the pathogenesis of BP, the lesions were thought to be cutaneous adverse events caused by IT. (Korean J Dermatol 2023;61(1):62∼65)