Prurigo nodularis (PN) is a disease characterized by chronic itch and presence of firm nodules or papules on the skin. The underlying pathophysiology of PN is still under debate, but it has been reported to be due to synergistic neural- and immune-mediated mechanisms. In this review, the authors summarize the etiology, epidemiology, clinical characteristics, and diagnosis of PN and suggest management protocols for patients with PN despite the absence of local guidelines for PN in Korea. The prevalence of PN in Korea was reported as 0.036%, similar to that in other countries. The various etiologies of PN are known to be associated with neural sensitization and inflammation, and the related treatment targets being studied for PN include interleukin-4, 13, 31, and transient receptor potential vanilloid 1 (TRPV1). Understanding of predisposing factors or concomitant diseases is beneficial towards targeted management of patients with PN. In addition, it has been reported that PN is more frequently accompanied by metabolic diseases, or renal disorders compared to other inflammatory skin diseases characterized by itchiness such as atopic dermatitis or psoriasis. The clinical diagnosis of PN is generally based on three core symptoms; chronic pruritus over six weeks, firm lesions, and repeated scratching. To evaluate the severity of PN, the following objective and subjective assessments can be used: Investigator’s Global Assessment for PN or Peak Pruritus Numerical Rating Scale. We propose a localized work-up algorithm for PN. It is expected that the increased awareness of PN can facilitate its diagnosis, thereby reducing the disease burden of patients with PN.

Renal cell carcinomas (RCC) account for 2.4% of all adult malignancies. RCC is known for its aggressive nature, with approximately one-third of patients presenting with metastasis at the time of diagnosis. Cutaneous metastasis is a rare presentation of this cancer. A 78-year-old male presented with numerous erythematous nodules of various sizes on the left flank, which he had had for a month. He had undergone a left partial nephrectomy for papillary RCC 3 years previously and had been receiving chemotherapy since surgery. Histopathology revealed papillary architecture with prominent atypical nucleoli throughout the dermis. Immunohistochemical findings were positive for CD10, cytokeratin 7, PAX-8, vimentin, and alpha-methylacyl-CoA racemase. These results led to a diagnosis of cutaneous metastases of papillary renal cell carcinoma. Papillary RCC rarely presents with cutaneous metastases.Because these lesions are easily accessible, cutaneous lesions in patients with risk factors for RCC should be excised and pathologically evaluated.

Background: Since the disease burden of atopic dermatitis (AD) understandably increases with its disease severity, studies, especially on the baseline characteristics of severe AD, have been conducted in some countries to deepen the understanding of the disease and, by extension, formulate a relevant national policy. However, research on the baseline characteristics of severe AD in Korea remains insufficient. Objective: To report the baseline demographics and describe the clinical characteristics of adult Korean patients with severe AD, including medical and treatment history, clinical manifestations, disease severity, and laboratory findings, in order to understand the characteristics of severe AD. Methods: A single-center, prospective, non-interventional, observational, longitudinal study of 108 patients with severe AD was conducted between January 2021 and December 2022. Clinical data and patient-reported measures of signs and symptoms of AD were recorded at baseline. Results: The mean Eczema Area and Severity Index score of the patients was 28.5±6.8. The mean pruritus numerical rating scale, Patient-Oriented Eczema Measure, Dermatology Life Quality Index, and Atopic Dermatitis Control Tool scores were 8.1±1.7, 23.6±4.8, 21.9±6.6, and 19.5±3.9, respectively. Although a larger proportion of the headeck and trunk are affected than both limbs, the key signs of AD were less severe in the headeck region than in the other regions. Erythema and lichenification were more representative clinical signs of severe AD than induration and excoriation. The baseline data on previous treatments reflected the AD treatment guidelines in Korea. Conclusion This real-world data will provide dermatologists with a better understanding of severe AD, which will eventually lead to better clinical and health policy decisions for patients with severe AD.