Youngkyoung Lim

Acquired perforating dermatosis (APD) is a group of conditions characterized by transepidermal elimination and extrusion of dermal components. Patients often present with severe pruritus to the degree of disordering daily life and have comorbid diabetes mellitus (DM) or chronic kidney disease (CKD). However, owing to the limited number of cases, unmet clinical needs exist for effective treatment in the absence of large‐scale clinical trials and established clinical guidelines. Therefore, this study aimed to broaden the scope of current APD treatment by investigating the role of Janus kinase (JAK) inhibitors through five case series, thereby adding to the two previously reported cases of APD treated with JAK inhibitors. Patients reported improvement in pruritus as early as 1 day with JAK inhibitor treatment, and this improvement was mainly observed within the first 4 weeks. Improvement in the hyperkeratotic nodule with central plug lesions was also observed. One patient developed herpes zoster reactivation during the course. The reduction of pruritus may be critical in disease management, both as a prominent symptom and a precipitating factor of APD. As the JAK–STAT pathway is suggested to play a critical role in IL‐31 signal transduction, a key cytokine in itching, JAK inhibitors may be an effective treatment for difficult‐to‐treat APD. Vigilant monitoring for adverse events, such as infection, with patient education is also warranted.

Previous studies suggested racial difference between young melanomas of Caucasians and non-Caucasians. This study aimed to elucidate characteristics of melanomas in young Asians. We analyzed clinical and histologic characteristics of patients under age 40 diagnosed with cutaneous melanomas including in situs. Survival and subgroup analyses were conducted. Among the 45 patients investigated, the most common anatomical sites of melanomas were lower extremities (22/45, 45.3%) and acral lentiginous type was the most common histological variety (18/45, 40%), of which 12 were subungual type. Lymph node involvement and nodular histologic type were significant prognostic factors. Age subgroup analysis revealed that clinical and histopathologic features of adolescents (15–21 years old [YO]) were distinct from those of young adults (22–39 YO), but similar to children (0–14 YO) who showed amelanotic nodules (p < 0.01) and spitzoid subtypes (p < 0.001). Pediatric melanomas (< 20 YO), showed racial differences based on sex (p < 0.01), an-atomical site (p < 0.001), histologic types (p < 0.001), and lymph node involvement at diagnosis (p < 0.047). Understanding the differences among age groups will help clinicians decide management of melanomas in young Asian patients.

Background: Studies on the interaction between tumour‐infiltrating immune cells (TIICs) and tumour cells in melanoma arising from congenital melanocytic nevus (CMN) are lacking.Objective: The aim of this study was to determine the intratumoral immune landscape of TIICs and tumour cells during invasion and metastasis.Methods: Tissue specimens were obtained from patients with melanoma originating from CMN. Differential gene expression in melanoma cells and TIICs during invasion and metastasis was determined using spatial transcriptomics.Results: As invasion depth increased, the expression of LGALS3, known to induce tumour‐driven immunosuppression, increased in melanoma cells. In T cells, the expression of genes that inhibit T‐cell activation increased with increasing invasion depth. In macrophages, the expression of genes related to the anti‐inflammatory M2 phenotype was upregulated with increasing invasion depth. Compared to primary tumour cells, melanoma cells in metastatic lesions showed upregulated expression of genes associated with cancer immune evasion, including AXL and EPHA2, which impede T‐cell recruitment, and BST2, associated with M2 polarization. Furthermore, T cells showed increased expression of genes related to immunosuppression, and macrophages exhibited increased expression of genes associated with the M2 phenotype.Conclusions: The interaction between melanomas arising from CMN and TIICs may be important for tumour progression and metastasis.

Background: Riehl melanosis, characterized by diffuse brown to grey hyperpigmentation of the face and neck, affects middle‐aged women with dark skin phototypes. Riehl melanosis prevalence has increased in Korea, and a relationship with henna hair dye has been suspected. In this study, we aimed to evaluate clinical features and patch test results of Riehl melanosis patients and analyse them according to age, sex, and hair dye use.Methods: We identified patients showing clinical and histopathological manifestations consistent with Riehl melanosis between January 2009 and December 2019 in our medical centre.Results: Of 154 patients, 76.5% had positive patch‐test results, and the most common sensitizing agents were nickel, cobalt, and benzyl salicylate. Patients ≥50 years old were more likely to have spotty hyperpigmentation and less likely to have diffuse patterns, while lesions in the younger‐aged group were more commonly accompanied by erythema. Preceding erythema was found more often in female patients. Hair dye usage was more likely to be associated with aggravation of symptoms in females. Patients who developed Riehl melanosis after hair‐dye use more frequently had lesions on the forehead and were diagnosed an average of 14.1 months earlier as compared with other patients. Short disease duration, aggravation by hair dye (except henna), laser therapy, and longer follow‐up periods were related to good treatment responses.Conclusions: Detailed history taking regarding disease duration and aggravating factors as well as the length of the period of laser therapy can be important for the management of Riehl melanosis patients.

Background: Distinguishing benign lesion from early malignancy in melanocytic lesions of the nail unit still remains a diagnostic challenge, both clinically and histopathologically. While several immunohistochemistry (IHC) stainings have been suggested to help discriminate benign subungual melanocytic proliferation (SMP) and subungual melanoma in situ (MIS), the diagnostic utility of IHC staining for cyclin D1 and PRAME has not been thoroughly investigated in melanocytic lesions of nail unit.Methods: This retrospective study included cases of benign SMP and subungual MIS confirmed by biopsy at Asan Medical Center from January 2016 to December 2020. Cases of melanocytic activation without proliferation and melanoma where dermal invasion was identified were excluded. Cyclin D1 and PRAME expression was assessed by counting proportion of melanocytes with nuclear positivity under 200x magnification.Results: A total of 14 patients with benign SMP and 13 patients with subungual MIS were included in this study. 11 patients with benign SMP (71.4%) and 5 patients with subungual MIS (38.5%) showed > 60% nuclear immunostaining for cyclin D1, respectively. While 13 patients with benign SMP (92.9%) showed totally negative staining for PRAME, 10 patients with subungual MIS (76.9%) exhibited > 50% nuclear immunostaining for PRAME. Using the cutoff of 10%, PRAME exhibited good overall discrimination between benign SMP and subungual MIS (AUC = 0.849, 95% CI = 0.659–0.957).Conclusions: This study suggests that PRAME IHC staining as a reliable discriminator in distinguishing subungual MIS from benign SMP.

Nail melanoma (NM) is an important differential diagnosis in patients with longitudinal melanonychia. However, diagnosis is often challenging as it is difficult to differentiate from other pigmented nail disorders. The main challenge for diagnosis is obtaining adequate nail matrix biopsy specimens for histopathological assessment. Furthermore, the histopathological changes in the early stages of NM are subtle and contribute to a delay in diagnosis and care. Therefore, the integration of clinical and histopathological analyses is essential. Clinical and dermoscopic features, such as a broadened width of asymmetric bands in an irregular pattern, with multicolour pigmentation, periungual pigmentation, and continuous growth, are features that support the diagnosis of NM. The essential histological features that must be assessed are cellular morphology, architectural features, melanocyte density, and inflammatory changes. The reported mutations in NMs were BRAF (0–43%), NRAS (0–31%), KIT (0–50%), NF1 (0–50%), and GNAQ (0–25%). Surgery is the primary treatment for NM. The recommended treatment for in situ or minimally invasive NM is functional surgery, but cases with suspected bone invasion should be treated with amputation. Targeted therapy and immunotherapy are indicated for advanced stages of NM. This review summarizes the updated guidelines for the diagnosis and treatment of NM.