Background: A picosecond laser irradiation technique has presented satisfactory cosmetic outcomes for the treatment of various pigmented lesions. We aimed to evaluate the clinical results of a picosecond neodymiumdoped:yttrium aluminum garnet (Nd:YAG) (PSNY) laser for the treatment of various pigmented lesions and to compare them with the results of a conventional Q-switched Nd:YAG laser. Methods: A retrospective review of subjects treated with a PSNY laser was performed. Clinical improvement was assessed by two blinded dermatologists using a 5-point Global Assessment Scale (GAS). Adverse events were also assessed. Results: Forty-eight patients were treated with a dual-wavelength (532-nm and/or 1,064-nm) PSNY laser. Sixteen of the 48 patients (33.3%) experienced more than 50% improvement after the PSNY treatment. Patients with café-au-lait macule showed the greatest improvement, which was fair to good (GAS, 3.80 ± 0.76). Patients with postinflammatory hyperpigmentation received the highest number of treatment sessions (6.60 ± 3.44 times). The duration of follow-up was the longest in patients with Ota’s nevus (22.50 ± 5.44 weeks). There were no serious complications during the treatment period. Conclusion In our case series, it was concluded that a dual-wavelength 532-nm and 1,064-nm PSNY laser was safe and effective for the treatment of pigmented lesions in Korean patients.

Background: In a previous study, rhinoplasty rasp was shown an effective method for removal of button osteoma (BO) of the skull. Objective: In the present study, our experience was presented and surgical outcome using high-speed burr in surgery for BO evaluated. Methods: The register-based surgery reports of patients who underwent local excision of BO (2010∼2023) at a single institution were reviewed. Demographics, photodocumentation, radiologic examinations, pathology reports, data of scar prevention, and surgical outcome in the BO study cohort were analyzed. Results: A total of 20 BO lesions in 18 patients (14 females and four males; mean age of 52.4±14.3 years) who underwent surgery using high-speed burr were assessed. The mean size of BO was 9.3 mm (range, 5∼17 mm).Most of the BOs were located on the forehead (19/20, 95.0%), which was associated with the course of the supratrochlear (n=13) or supraorbital nerve (n=6). Minimal hematoma was complicated in three patients (16.7%).Delayed complications, recurrence, and severe scarring during the mean follow-up of 3.1±3.5 months were not reported. Conclusion The use of high-speed burr for surface smoothening may provide good surgical results in minimally invasive BO surgery.

Background: The exact definition of sensitive skin is not established yet. Since its high prevalence and significant influence on quality of life, it has become an important topic of research. Among various ingredients, conditioned media from umbilical cord blood-derived mesenchymal stem cells (UCB-MSC-CM) can be a promising source for the treatment of sensitive skin. Objective: We evaluated the efficacy and safety of UCB-MSC-CM on patients with sensitive skin. Methods: We designed a randomized, single blinded, prospective, split-face comparison study and enrolled thirty patients. All patients underwent nonablative fractional laser over the entire face before UCB-MSC-CM or normal saline was applied. Each facial area was randomly assigned to undergo treatment with either UCB-MSC-CM or normal saline. We performed three sessions at two-week intervals, and final results were assessed on six weeks after the last session. As an outcome measure, we evaluated a five-point global assessment scale, transepidermal water loss (TEWL), erythema index (EI) and Sensitive Scale-10. Twenty seven subjects were included in final analysis. Results: The treated side exhibited greater improvement compared to the untreated side based on a five-point global assessment scale. TEWL, EI of the treated side were significantly lower than those of the untreated side throughout study period. Sensitive Scale-10 was significantly improved after treatment. Conclusion The application of UCB-MSC-CM resulted in improved skin barrier function and reduced inflammatory responsiveness, which could provide beneficial effect on sensitive skin.

Primary localized cutaneous amyloidosis (PLCA) is characterized by extracellular deposition of pathological fibril aggregation of proteins in the skin without systemic involvement.Macular amyloidosis, lichen (papular) amyloidosis, and nodular amyloidosis are three different subtypes of PLCA. Although the pathological mechanism of PLCA has not yet been clarified, it is assumed that a nucleus formation of amyloid fibril is formed due to repeated external stimulation, such as subcutaneous injection, which often poses diagnostic challenges. Herein, we present a 54-year-old Korean male patient with cutaneous localized amyloidosis which occurred after repeated local insulin injections, and discuss the relationship between insulin therapy in patients with diabetes mellitus and dermal amyloid deposition.

Fixed drug eruption (FDE) is a well-defined hyperpigmented patch that recurs in a fixed location each time a particular drug is taken. Common causative agents of FDE are nonsteroidal anti-inflammatory drugs, non-narcotic analgesics, sedatives, anticonvulsants, sulfonamides, and tetracycline. We report a 33-year-old male who presented with a recurrent, localized, brownish-to-erythematous macule and papules on the peri-philtrum area two hours after taking valacyclovir. Three episodes of valacyclovir ingestion for treatment of Herpes simplex virus infection provoked a similar skin rash at the same site. Histopathology results showed vacuolar degeneration in the basal layer of the epidermis, pigmentary incontinence, and perivascular inflammatory cell infiltration in the papillary dermis. Although patch test and skin prick test showed negative responses to acyclovir and valacyclovir, an intradermal test showed a positive reaction only to valacyclovir. The oral provocation test to acyclovir and valacyclovir showed a positive reaction only to valacyclovir. Through drug history, histopathological examination, patch test, intradermal test, and oral provocation test, we established a final diagnosis of FDE due to valacyclovir without cross-reactivity to acyclovir. To find alternative therapeutic drugs, we suggest diagnostic tests with not only the suspected drugs, but also other drugs in the same class.

Pilomatricoma is a common benign tumor that originates from hair matrix cells. Bullous pilomatricoma (BP) is a rare variant that often occurs on the upper extremities. A 23-year-old male presented with a cyst on the left upper arm for 6 months. He received the BNT162b2 (Pfizer) mRNA COVID-19 vaccine in the same location approximately 6 months prior to presentation. The lesion appeared 1 week after inoculation and gradually enlarged.Physical examination revealed a 2.5-×2.0-cm-sized, pinkish cystic nodule on the left upper arm. The lesion was excised, and histopathological examination showed a well-circumscribed nodule composed of basophilic cells and eosinophilic shadow cells. Finally, the patient was diagnosed with BP. The exact cause of BP formation following vaccination is yet to be determined; however, this report presents the possibility of BP occurrence in individuals with chronic skin lesions at the site of vaccination.

Epithelioid blue nevus (EBN) is a rare variant of blue nevus characterized by large polygonal pigmented melanocytes. As EBN was first described in patients with Carney complex, familial lentiginosis, and low-grade multi-organ neoplasia syndrome, sporadic cases without such clinical features have been reported and debated as having considerable histopathological overlap with animal-type melanoma. A 34-year-old male presented with a well-defined, 2.0-×1.8-cm-sized, dome-shaped, grayish mass on the anterior aspect of the left ankle. A complete surgical resection of the lesion was performed. Histopathological findings revealed a well-circumscribed round tumor in the reticular dermis. Heavily pigmented epithelioid melanocytes were admixed with the collagen bundles. The lesion was diagnosed as EBN. A follow-up period of 9 months showed no evidence of recurrence or metastasis.Here, we report a sporadic case of EBN, which is rare in the Korean population.