Background: Basal cell carcinoma (BCC) is the most common type of skin cancer. However, limited comparative data on the characteristics and prognosis of BCC in the H-zone and non-H-zone exist. Objective: We aimed to compare the clinical, histopathological, and surgical characteristics of BCCs in the head and neck region between the H- and non-H-zones. Methods: We retrospectively reviewed the clinical and histopathological characteristics of 292 head and neck BCC lesions in 275 patients and the characteristics of Mohs micrographic surgery (MMS) of 252 BCC lesions in 239 patients. Results: In the H-zone, 226 lesions (77.4%) were found. Clinically, patients with H-zone BCC, compared to those with non-H-zone, were significantly older (71.6±11.4 years vs. 64.6±13.5 years) and smaller in diameter (10.1±7.1 mm vs. 12.4±9.9 mm). The noduloulcerative type was more frequent in the H-zone, while the superficial and morpheaform types in the non-H-zone. Histopathologically, the infiltrative subtype was particularly noted in the H-zone than the non-H-zone (7.5% vs. 1.5%). Out of 37 BCC patients with prior treatment history, 31 (83.8%) were in the H-zone. Two out of 252 lesions (0.8%) recurred after MMS at our institution. The mean stages of MMS were comparable between the H- and non-H-zones (1.59 vs. 1.45, p=0.135). Conclusion H-zone BCCs were associated with older age and smaller tumor size compared to the non-H-zone BCCs. The noduloulcerative clinical and nodulocystic pathologic subtypes were the most common in both H-zone and non-H-zone BCCs.

Langerhans cell histiocytosis (LCH) is a rare inflammatory neoplasia of the dendritic cells that can affect the whole body and commonly affect the pediatric age. Adult onset LCH is relatively rare, and the cutaneous form without any other organ involvement is much more uncommon. A 62-year-old woman visited the clinic presenting pruritic erythematous papule and nodules on the whole body, from which she suffered for several years. Skin biopsy showed hyperkeratosis, mild acanthosis, intra-epidermal tumor cell infiltration, and band-like tumor cell infiltration. Cells infiltrating the epidermis and dermis showed characteristics consistent with Langerhans cells. Immunohistochemical analysis revealed tumor cells highlighted with CD1a and S-100, but not with CD68, and therefore, diagnosed as LCH. The patient showed no evidence of any other organ manifestation, which led the final diagnosis of single-system LCH. This case highlights a rare adult-onset cutaneous form of single-system LCH with skin manifestations very similar to prurigo nodularis.

A 62-year-old man with multiple myeloma visited our clinic with multiple painful erythematous to purpuric nodules on his whole body. He received a skin biopsy which showed septal and lobular inflammation with vasculitis, and multiple amoebic organisms were found.Polymerase chain reaction and culture were performed and an Acanthamoeba triangularis infection was diagnosed. This is the first report on cutaneous acanthamoebiasis caused by A. triangularis, suggesting that A. triangularis should be regarded as a clinical pathogen that can cause ocular as well as disseminated infection.

Background: In the current situation, where severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is rapidly spreading, vaccines for coronavirus are thought to be the most effective approach to containing the situation.However, limited comparative data are available on cutaneous adverse reactions to coronavirus vaccination in Korea. Objective: We retrospectively reviewed the clinical and histopathological characteristics of adverse cutaneous reactions following coronavirus vaccination. Methods: We retrospectively reviewed the clinical and histopathological characteristics of 95 patients who were vaccinated with Pfizer, Moderna, AstraZeneca, and Janssen vaccines and visited the Dermatology Departments of Dankook University Hospital and Chungnam National University Hospital. Results: The mean age was 49.3±17.5 years. Patients who received the AstraZeneca vaccine had an average age of 61.7±10.8 years, significantly higher than those in the Pfizer (44.1±18.7 years) and Moderna (42.5±15.0 years) groups (p＜0.001). Of the 95 patients, 36 (37.9%) were diagnosed with urticaria, 24 (25.3%) with morbilliform eruption, 18 (18.9%) with petechiae and purpura, and eight (8.4%) with erythema multiforme. Additionally, there were diagnoses of erythema nodosum, alopecia areata, eczema, generalized pustular psoriasis, acute generalized exanthematous pustulosis, pityriasis rosea, and bullous pemphigoid. In the AstraZeneca-vaccinated group, the proportion of morbilliform eruptions was significantly higher than that in the Pfizer- and Moderna-vaccinated groups (p=0.008). The Pfizer- and Moderna-vaccinated groups had higher rates of urticaria than did the AstraZeneca-vaccinated group. However, this difference was not statistically significant (p=0.083). Conclusion This study described the clinical characteristics of cutaneous adverse reactions after coronavirus vaccination.