Hystrix-like ichthyosis and deafness (HID) syndrome is a rare ectodermal dysplasia characterized by erythrokeratoderma and hearing impairments. HID syndrome is a nonocular variant of keratitis ichthyosis deafness (KID) syndrome caused by an autosomal dominant mutation in the gap junction protein β 2 (GJB2) gene. The GJB2 gene encodes connexin 26, a transmembrane protein involved in cell–cell attachment in almost all tissues. We report a case of a 25-year-old man with generalized hyperkeratotic plaques, diffuse palmoplantar keratoderma, and nail deformities since birth. The patient also had a history of recurrent bacterial skin infections in the existing hyperkeratotic lesions. Histopathological examination revealed compact hyperkeratosis and irregular acanthosis in the epidermis, along with upper dermal lymphocytic infiltration. Audiometry revealed high-frequency sensorineural hearing loss. Genetic analysis revealed a missense mutation in the GJB2 gene. Based on clinicopathological findings and genetic testing, HID syndrome was diagnosed.

Granuloma annulare is a relatively common inflammatory skin disease. The etiology is unknown; however, drugs have been considered as one of the predisposing conditions, and a few cases of granuloma annulare related to biologics have been recently reported. A 48-year-old man with a 25-year history of psoriasis visited our dermatological clinic. Ustekinumab was administered for the treatment of psoriasis. After 5 years of ustekinumab therapy, erythematous papules with an annular distribution appeared on his trunk and extremities. Skin biopsy supported the diagnosis of generalized granuloma annulare, and the patient continued to receive ustekinumab with oral methotrexate, cyclosporine, and steroids for 9 months. However, as the skin lesions aggravated, oral steroid treatment was continued, and secukinumab was administered instead of ustekinumab. The skin lesions improved and remained stable with the intermittent administration of oral steroids thereafter.

Epidermal cysts are the most common cutaneous cysts that originate from the hair follicles. Therefore, they are rarely found in areas without hair follicles, such as the palms, soles, and subungual areas. Herein, we reported two cases of subungual epidermoid implantation cysts. The first patient was a 52-year-old male who presented with onycholysis and a subungual white mass on the middle fingernail of the right hand. The second patient was a 67-year-old male who presented with an erythematous patch and swelling of the proximal nail fold of the right thumb. Ultrasonography revealed bone erosion and a round-to-elliptical mass with internal avascularity. Heterogeneous echogenicity and internal echogenic foci were detected in both patients. After nail avulsion, a skin-colored mass was observed. Histopathological examination revealed typical epidermal cysts in both patients. Herein, we report two rare cases of subungual epidermoid implantation cysts.

Background: Dupilumab is a human monoclonal antibody against interleukin-4 receptor α. Several clinical trials have demonstrated the rapid and excellent therapeutic effects of dupilumab. Although a growing number of studies have reported data on the real-world efficacy and safety of dupilumab for the treatment of atopic dermatitis, data on real-world experiences in Korea are limited. Objective: To evaluate the real-world efficacy and safety of dupilumab for the treatment of moderate-to-severe atopic dermatitis in Korean patients. Methods: This was a retrospective, single-center study. A total of 179 patients treated with dupilumab for at least 16 weeks were enrolled in this study. Based on electronic medical records, the clinical characteristics, Eczema Area and Severity Index (EASI) score, and adverse events were investigated. Results: The mean baseline EASI score (26.5±7.2) significantly decreased at weeks 16, 40, 52, and 112 (p＜0.05). All and 55.2% of patients achieved EASI75 and EASI90 responses at week 52, and all and 75.0% of patients achieved EASI75 and EASI90 responses at week 112, respectively. Common adverse events were facial erythema (31.8%), conjunctivitis (24.0%), and herpes simplex virus infection (11.2%). Three serious adverse events of severe conjunctivitis, mycosis fungoides, and mesenteric venous thrombosis resulted in discontinuation of dupilumab. Conclusion Dupilumab was effective in real-world clinical practice with a favorable safety profile in Korean patients with moderate-to-severe atopic dermatitis.

Weathering nodules are benign skin conditions of the ear typically occurring in patients with a history of persistent sun exposure. Clinically, they appear as multiple localized, skin-colored to whitish papules or nodules in the ear helix. Histopathologically, weathering nodules are characterized by chondroid metaplasia with spurs of fibrous tissue extending upward from the disrupted perichondrium of the underlying pinna cartilage. We report the case of a 19-year-old man who presented with multiple localized whitish papules on the right ear helix for a month. The lesions were asymptomatic and accompanied by a blanch sign. Histopathological examination revealed chondroid metaplasia in the dermis, separate from the pinna cartilage. Based on the clinicopathological findings, weathering nodules of the ear was diagnosed.