Pigmented contact dermatitis and hair dyes: A retrospective case-control multicentre study in Korea.

BACKGROUND: Pigmented contact dermatitis (PCD), a rare variant of non-eczematous contact dermatitis, is clinically characterized by sudden-onset brown or grey pigmentation on the face and neck. It is hypothesized to be caused by repeated contact with low levels of allergens. OBJECTIVES: This study evaluated the risk of using hair dyes in patients with PCD in Korea. METHODS: A total of 1033 PCD patients and 1366 controls from 31 university hospitals were retrospectively recruited. We collected and analysed the data from the patient group, diagnosed through typical clinical findings of PCD and the control group, which comprised age/sex-matched patients who visited the participating hospitals with pre-existing skin diseases other than current allergic disease or PCD. RESULTS: Melasma and photosensitivity were significantly more common in the control group, and a history of contact dermatitis was more common in the PCD group. There were significantly more Fitzpatrick skin type V participants in the PCD group than in the control group. There was no significant difference in sunscreen use between the groups. Using dermatologic medical history, Fitzpatrick skin type and sunscreen use as covariates, we showed that hair dye use carried a higher PCD risk (odds ratio [OR] before adjustment: 2.06, confidence interval [CI]: 1.60-2.65; OR after adjustment: 2.74, CI: 1.88-4.00). Moreover, henna users had a higher risk of PCD (OR before adjustment: 5.51, CI: 4.07-7.47; OR after adjustment: 7.02, CI: 4.59-10.74), indicating a significant increase in the risk of PCD with henna dye use. Contact dermatitis history was more prevalent in henna users than in those using other hair dyes in the PCD group (17.23% vs. 11.55%). CONCLUSION: Hair dye use is a risk factor for PCD. The risk significantly increased when henna hair dye was used by those with a history of contact dermatitis.

The Low-Fluence Q-Switched Nd:YAG Laser Treatment for Melasma: A Systematic Review.

Melasma is a common pigmentary disorder with a complex pathogenesis, of which the treatment is challenging. Conventional treatment often leads to inconsistent results with unexpected pigmentary side effects and high recurrence rates. Recently, the low-fluence Q-switched Nd:YAG laser (LFQSNY) has been widely used for treating melasma, especially in Asia. We reviewed literatures on the LFQSNY treatment of melasma published between 2009 and May 2022 to evaluate the efficacy and adverse events, including its combination therapy. A systematic PubMed search was conducted and a total of 42 articles were included in this study. It was hard to summarize the heterogenous studies, but LFQSNY appeared to be a generally effective and safe treatment for melasma considering the results of previous conventional therapies. However, mottled hypopigmentation has been occasionally reported to develop and persist as an adverse event of LFQSNY, which may be associated with the high accumulated laser energy. When used aggressively, even LFQSNY can induce hyperpigmentation via unwanted inflammation, especially in darker skin. Although few studies have reported considerable recurrence rates three months after treatment, unfortunately, there is a lack of the long-term follow-up results of LFQSNY in melasma. To enhance the effectiveness and reduce the adverse events, LFQSNY has been used in combination with other treatment modalities in melasma, including topical bleaching agents, oral tranexamic acid, chemical peeling, or diverse energy-based devices, which generally reduced side effects with or without significant superior efficacy compared to LFQSNY alone.

Erythema induratum of Bazin in a 10-year-old boy.

Erythema induratum of Bazin (EIB) is a form of tuberculid resulting from hypersensitivity to tuberculosis antigen. EIB occurs most commonly in middle-aged women and is not typically seen in children. Here, we present a rare case of EIB, presenting as a chronic nodular panniculitis, in a 10-year-old Korean boy.

Anesthetic cream relieves pain after cryotherapy treatment of plantar and palmar warts.

Cryotherapy using liquid nitrogen is an effective and commonly used treatment for palmoplantar warts. However, pain can be a limiting factor in the effective use of cryotherapy. In this study, we found that a single application of anesthetic cream following cryotherapy treatment of warts reduced posttreatment pain and led to improved tolerability of the procedure.

Vitiligo and overt thyroid diseases: A nationwide population-based study in Korea.

BACKGROUND: Associations between vitiligo and thyroid diseases have been reported repeatedly. OBJECTIVE: We investigated the associations between vitiligo and overt autoimmune thyroid diseases and thyroid cancer using the Korean National Health Insurance claims database. METHODS: We defined patients with vitiligo as those whose records showed ≥4 physician contacts between 2009 and 2013 in which vitiligo was the principal diagnosis. We also established an age- and sex-matched control group without vitiligo (2 per 1 vitiligo patient). The outcomes of interest were concurrent Graves disease and Hashimoto thyroiditis (the patients were taking relevant thyroid medications) and thyroid cancer. RESULTS: The study enrolled 73,336 vitiligo patients and 146,672 controls. Patients with vitiligo were at increased risks of Graves disease (odds ratio [OR] 2.610 [95% confidence interval {CI} 2.319-02.938]), Hashimoto thyroiditis (OR 1.609 [95% CI 1.437-1.802]), and thyroid cancer (OR 1.127 [95% CI 1.022-1.242]), compared with the controls. The associations were consistently stronger in males and younger patients. LIMITATIONS: Individual clinical information was not available, and the homogeneous population may limit the generalizability of the results. CONCLUSION: Vitiligo was significantly associated with overt autoimmune thyroid diseases and overt thyroid cancer.

Subungual Posttraumatic Ectopic Nail.

Ectopic nail is defined as the malformation of nail tissue in a location other than the usual nail unit. We present a 12-year-old boy with a single dystrophic thumb nail after an injury. The nail was observed under the original nail and it is linked to the original nail plate by longitudinal bridge formation with parallel growth. According to these clinical findings, the diagnosis of subungual posttraumatic ectopic nail was made.

A Rare Case of Atypical Myxoid Cellular Neurothekeoma in a 6-Year-Old Girl.

Neurothekeoma (nerve sheath myxoma)is a benign tumor of probable nerve sheath origin. The atypical cellular variant of this tumor, showing a peculiar histologic pattern, has been very rarely reported in the literature. The atypical variant of cellular neurothekeoma is characterized by features such as large size, deep penetration extending into skeletal muscle and/or subcutaneous fat, diffuse infiltration borders, vascular invasion, high mitotic rate and marked cytologic pleomorphism. We describe a rare form of atypical myxoid cellular neurothekeoma in a 6-year-old girl.

A Rare Case of Localized Hypertrichosis in Conjunction with Erythema Nodosum.

Acquired hypertrichosis can occur in local inflammation. Erythema nodosum (EN) is a hypersensitivity reaction to various underlying antigenic stimuli including Mycobacterium tuberculosis, which causes inflammation in the septa of subcutaneous fat. There were several case reports that describe the association of localized hypertrichosis (LH) with traumatic panniculitis and lupus panniculitis. To our knowledge, this is the first reported case of acquired LH associated with EN. Thus, EN can be added to the list of causes of localized hypertrichosis.

Hybrid cysts: a clinicopathological study of seven cases.

Hybrid cysts develop from more than two components of the pilosebaceous unit. The pathogenesis of this unusual disease has not yet been elucidated. The aim of this study was to assess the clinical and histopathological features of hybrid cysts. Histological sections of seven cases indexed as hybrid cysts were reviewed from 1996-2009 at the Department of Dermatology, Eulji Medical Center, Seoul, Korea. Hospital charts and slides were retrospectively evaluated. All cases had a combination of an epidermal cyst and a pilomatricoma with sharp transitional zones. The epidermal cyst lining was composed of thickened stratified squamous epithelium with a granular layer. Basophilic cells, shadow cells and the contents of the pilomatricoma were present in all lesions. There were no differences in the clinical features between patients with hybrid cysts and others with single cystic lesions. There were five women and two men, ranging in age from 11 to 50 years (mean 27 years). The most common sites were the upper extremities. None of the patients had any sign of Gardner's syndrome. Hybrid cysts are an interesting pathological phenomenon. Further study is needed to analyze hybrid cysts to improve our understanding of their pathogenesis and development from tumours of the pilosebaceous unit.

Use of hydroxychloroquine in dermatology: A multicenter retrospective study in Korea.

Despite the expanding clinical application of hydroxychloroquine in dermatology, the overall data on hydroxychloroquine use among dermatologists are limited. With retrospective review of the medical records of the 790 patients who were prescribed hydroxychloroquine, we classified the diagnoses into 12 disease categories, the lupus erythematosus group being the largest. The lupus erythematosus group had the longest prescription duration (median, 6.2 months), whereas the photodermatitis group had a significantly shorter prescription duration (median, 0.5 months). The overall good response rate was 77.1%. The photodermatitis group had the best response (88.7%), followed by the lupus panniculitis (85.1%) and lichen planus (84.4%). In conclusion, hydroxychloroquine has proven utility for various inflammatory skin diseases, including but not limited to cutaneous lupus erythematosus.

A nodular syphilid presenting as a pseudolymphoma: mimicking a cutaneous marginal zone B-cell lymphoma.

Syphilis has been referred to as the great imitator, the great mimic, and the great masquerader. It often presents with clinical and histological findings similar to many other dermatological conditions. We report a patient presenting with nodular plaques, a rare form of secondary syphilis. The histological features revealed a pseudolymphoma mimicking a cutaneous marginal zone B-cell lymphoma. Syphilis should be considered in the differential diagnosis of a cutaneous lymphoreticular process.