Factors Influencing the Treatment Effect of Superelastic Wire Orthonyxia for Nail Plate Deformity.

BACKGROUND: Orthonyxia is an effective, noninvasive treatment for transverse nail curvature deformity. OBJECTIVE: To discover the factors influencing treatment results of superelastic wire orthonyxia (SEWO). MATERIAL AND METHODS: A retrospective study was conducted using clinical records of patients treated with SEWO. A multiple linear regression model was used to explain the correlation between correction pace (% per week) and the other collected variables (patient age, sex, position of treated toe, wire diameter [WD, mm], wire residence time [WRT, weeks], nail plate thickness [PT, mm], baseline nail curvature index [NCI], number of previous treatments, and the correction pace of previous treatments [CPT, % per week]). A logistic regression model was used to identify risk factors for adverse effects. RESULTS: A total of 475 cases were collected from 197 patients. The correction pace was positively related to baseline NCI, WD, and correction pace in previous treatment. Also, it was negatively related to WRT and nail PT. No clinical factor was correlated with the occurrence of side effects. CONCLUSION: The correction pace of SEWO is affected by the baseline NCI, the diameter of the wire, nail PT, the CPT, and the WRT.

A cellular blue nevus with pigmented epithelioid melanocytoma-like pattern on the ipsilateral upper arm associated with a congenital plaque-type blue nevus on the hand.

A 36-year-old man presented with a subcutaneous nodule on the right upper arm. A small nodule had developed 8 years earlier, and grew in size, accompanied by a tingling sensation and numbness. In addition, he had a bluish irregular patch on the right hand since birth, which crossed from the palm to the dorsal hand. Skin biopsies from the hand showed a heavily pigmented melanocyte proliferation in the dermis with perieccrine, perivascular, and perineural involvement, and a diagnosis of congenital plaque-type blue nevus was made. The tumor on the arm was located closely along the median nerve, and was observed as a large black pedunculated round tumor. Histopathologically, the tumor on the arm consisted of densely packed tissue with nevoid cells without atypia in the larger nodular part, and heavily pigmented spindle and epithelioid melanocytes in the slender stalk area, which was diagnosed as cellular blue nevus with pigmented epithelioid melanocytoma-like pattern. Next-generation sequencing revealed GNAQ mutations in the hand lesion, and in the lesions on the arm. This case suggests that the areas of skin following the same neural distribution of a congenital plaque-type blue nevus on the extremities should be followed up for secondary changes.

MART-1-labeled melanocyte density and distribution in actinic keratosis and squamous cell cancer in situ: Pagetoid melanocytes are a potential source of misdiagnosis as melanoma in situ.

BACKGROUND: Actinic keratosis (AK) and squamous cell carcinoma in-situ (SCCIS) within or near melanoma in situ (MIS) can complicate diagnosis due to overlapping clinical and microscopic features. This study aimed to describe basilar melanocyte density and pagetoid spread in AK and SCCIS for improved diagnostic accuracy. METHODS: A total of 22 AK and 22 SCCIS biopsies containing a margin of uninvolved epidermis were immunostained with MART-1 (melanoma antigen recognized by T-cells 1). The basilar melanocyte:keratinocyte ratio and the number and distribution of pagetoid melanocytes were compared in AK, SCCIS, and uninvolved epidermis. An in-vitro human skin model was created to assess the impact of keratinocyte atypia on melanocyte distribution. RESULTS: The median basilar melanocyte:keratinocyte ratio in SCCIS (1:11.49) was lower than in uninvolved epidermis (1:5.59, P = 0.0011), and the ratio in AK (1:6.94) was similar to uninvolved epidermis (P = 0.987). Pagetoid melanocytes were absent in perilesional skin but common in AK (21/22, P < 0.0001) and SCCIS (22/22, P < 0.0001). Pagetoid melanocytes at or above the mid-spinous layer were more common in SCCIS (21/22) vs AK (7/22, P < 0.0001). Pagetoid melanocytes were present in the in-vitro skin model made with neoplastic but not normal keratinocytes. CONCLUSIONS: Pagetoid melanocytes in AK and SCCIS should be interpreted with caution to avoid overdiagnosis of MIS.

Disseminated juvenile xanthogranuloma occurring after treatment of Langerhans cell histiocytosis: a case report.

CASE PRESENTATION: An 11-year-old boy presented with a complaint of a painful temporal mass. Brain magnetic resonance imaging (MRI) showed a 3-cm-sized, homogeneously enhancing mass in the greater wing of the left sphenoid bone, which was diagnosed as Langerhans cell histiocytosis (LCH). Chemotherapy with vincristine and prednisolone was performed for 1 year. After 1 year and 11 months off treatment, he developed symptoms such as polydipsia and polyuria. Brain MRI showed thickening of the pituitary stalk with enhancement, suggestive of LCH involvement, and no recurrence in the sphenoid bone. After 4 years and 4 months off treatment, he developed multiple, subcutaneous, asymptomatic, and yellowish variable-sized papules on his face, posterior neck, and back, which were pathologically diagnosed as juvenile xanthogranuloma (JXG). Brain MRI revealed multifocal enhancing skull lesions in the left parietal, right frontal, and left occipital bones, which were also diagnosed as JXG. After 5 years and 8 months off treatment, the number of variable-sized skin lesions was increased without changes in the lesions in the skull and pituitary stalk. CONCLUSION: We report a case of disseminated JXG occurring after treatment of LCH. These clinical co-presentations suggested a close relationship between their pathogenesis.

Anatomic mapping and clinicopathologic analysis of benign acral melanocytic neoplasms: A comparison between adults and children.

BACKGROUND: The clinicopathologic features of benign acral melanocytic neoplasms (BAMNs) remain poorly understood. OBJECTIVE: To define the clinicopathologic features of BAMNs. METHODS: We analyzed clinical data and mapped BAMNs anatomically. We also reviewed the histopathologic features of BAMNs and compared these between adults and children. RESULTS: We included 396 cases of BAMN: 335 adults and 61 children (376 acquired and 20 congenital lesions). Anatomic mapping revealed that the nonweight-bearing portion of the foot was the most common site in adults (120/335, 35.8%) and the forefoot the most common site in children (17/61, 27.9%) for BAMNs. The long axes of the BAMNs paralleled the dermatoglyphic lines on the palms and soles, as did most tissue sections. The lesion diameters were <5.7 mm in all acquired lesions. Histopathologically, we diagnosed 69 lentigo simplex, 201 junctional, 114 compound, 8 intradermal, and 4 blue nevi. Corneal pigmentation, nests located between rete ridges, dendrite prominence, and cytologic atypia were all significantly more common in children than adults. LIMITATIONS: The retrospective study design and acquiring patients from a single institution of a single country limited the research results. CONCLUSION: BAMNs develop most commonly on nonweight-bearing regions of the soles in adults and on the forefoot in children. The long axis of the lesion follows the dermatoglyphics, and cytologic atypia is more common in children.

Light-emitting diodes downregulate cathelicidin, kallikrein and toll-like receptor 2 expressions in keratinocytes and rosacea-like mouse skin.

Cathelicidin (LL-37), Toll-like receptor 2 (TLR-2) and kallikreins (KLKs) are key inflammatory mediators in rosacea. Laser or light-based devices have been successfully used for rosacea. We investigated the effects of light-emitting diodes (LEDs) on LL-37, KLKs, TLR-2 and protease activity in cultured normal human epidermal keratinocytes (NHEKs) and rosacea-like mouse skin (RLMS). LL-37, KLK5, KLK7 and vitamin D receptor were induced by 1α, 25-dihydroxyvitamin D3 (VD3 ) and TLR-2 by Ad-CMV transfection in cultured NHEKs. NHEKs were subjected to LED irradiation at differing wavelengths (480-940 nm) and fluences (1-40 J/cm2 ). Inflammatory mediators were analysed with RT-PCR and real-time PCR and protease activity analysis and immunocytofluorescence staining were performed for NHEKs. Changes in RLMS induced by LL-37 peptide were evaluated with real-time PCR, immunohistochemical staining and enzyme-linked immunosorbent assay. In NHEKs, LED at 630 and 940 nm significantly attenuated LL37, KLK5 and TLR-2 mRNA expressions. Protease activity was significantly suppressed at 630, 850 and 940 nm. In the RLMS, LL-37, KLK5 and PAR-2 mRNA expressions significantly decreased at 24 and 48 hours after LED irradiation was performed three times at 630 and 940 nm. mCAMP and IL-8 protein levels and protease activity after LED irradiation were lower than those in RLMS control groups. LED at 630 and 940 nm downregulated TLR-2, KLK5 and LL-37 expressions and protease activity in NHEK and RLMS. Thus, LEDs may be promising for rosacea treatment. However, clinical trials are required for further study.

Update on Thin Melanoma: Outcome of an International Workshop.

The following communication summarizes the proceedings of a 1-day Workshop of the International Melanoma Pathology Study Group, which was devoted to thin melanoma. The definitions and histologic criteria for thin melanoma were reviewed. The principal differential diagnostic problems mentioned included the distinction of thin melanoma from nevi, especially from nevi of special site, irritated nevi, inflamed and regressing nevi, and dysplastic nevi. Histologic criteria for this analysis were discussed and the importance of clinico-pathologic correlation, especially in acral sites, was emphasized. Criteria for the minimal definition of invasion were also discussed. In addition, a new technique of m-RNA expression profiling with 14 genes was presented and facilitated the distinction of thin melanomas from nevus in histologically obvious cases. However, for particular nevi, it was not obvious why the results indicated a malignant lesion. Despite many molecular and other ancillary investigations, Breslow thickness remains the most important prognostic factor in thin melanoma. The prognostic significance of radial (horizontal) and vertical growth phases, Clark level, regression, and mitotic rate were also discussed. Because of the increasing frequency of thin melanomas, there is a great need to develop more refined predictors of thin melanomas with worse clinical outcome.

Other primary systemic cancers in patients with melanoma: Analysis of balanced acral and nonacral melanomas.

BACKGROUND: Although other primary systemic cancers in patients with melanoma have been studied, there have been few focusing on acral melanomas. OBJECTIVES: We assessed other primary systemic cancers in patients with acral and nonacral melanomas. METHODS: We analyzed other primary cancers in 452 patients with melanoma from 1994 to 2013. Metachronous cancers were defined as those given a diagnosis more than 2 months after diagnosis of melanoma. The others were considered prechronous or synchronous cancers. RESULTS: Among 51 cases of other primary cancers, gastrointestinal cancer (35.3%, n = 18/51) was the most common, followed by thyroid (17.6%), lung (11.8%), and breast (5.9%). Those were more prevalent in the acral melanoma group (12.8%, n = 31/243) compared with the nonacral melanoma group (9.6%, n = 20/209). Of 23 cases of metachronous cancer, the risk was the highest in bone marrow, followed by oral cavity, bladder, colon, lung, and thyroid. Among 28 cases of prechronous or synchronous cancers, gastrointestinal tract (35.7%, n = 10/28) was the most common site, followed by thyroid (17.9%), breast (10.7%), and lung (7.1%). LIMITATIONS: The study is limited by a small number of patients. CONCLUSION: Careful follow-up and imaging studies are necessary for early detection of other primary cancers and metastatic lesions in patients with melanoma.

Evaluation of the Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis (MPATH-Dx) classification scheme for diagnosis of cutaneous melanocytic neoplasms: Results from the International Melanoma Pathology Study Group.

BACKGROUND: Pathologists use diverse terminology when interpreting melanocytic neoplasms, potentially compromising quality of care. OBJECTIVE: We sought to evaluate the Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis (MPATH-Dx) scheme, a 5-category classification system for melanocytic lesions. METHODS: Participants (n = 16) of the 2013 International Melanoma Pathology Study Group Workshop provided independent case-level diagnoses and treatment suggestions for 48 melanocytic lesions. Individual diagnoses (including, when necessary, least and most severe diagnoses) were mapped to corresponding MPATH-Dx classes. Interrater agreement and correlation between MPATH-Dx categorization and treatment suggestions were evaluated. RESULTS: Most participants were board-certified dermatopathologists (n = 15), age 50 years or older (n = 12), male (n = 9), based in the United States (n = 11), and primary academic faculty (n = 14). Overall, participants generated 634 case-level diagnoses with treatment suggestions. Mean weighted kappa coefficients for diagnostic agreement after MPATH-Dx mapping (assuming least and most severe diagnoses, when necessary) were 0.70 (95% confidence interval 0.68-0.71) and 0.72 (95% confidence interval 0.71-0.73), respectively, whereas correlation between MPATH-Dx categorization and treatment suggestions was 0.91. LIMITATIONS: This was a small sample size of experienced pathologists in a testing situation. CONCLUSION: Varying diagnostic nomenclature can be classified into a concise hierarchy using the MPATH-Dx scheme. Further research is needed to determine whether this classification system can facilitate diagnostic concordance in general pathology practice and improve patient care.

Correlations between inflammatory cytokine levels and degree of pigmentation in acral melanomas.

Cutaneous melanoma, a highly aggressive skin tumor, is characterized by complex signaling pathways in terms of its pathogenesis and progression. Although the degree of pigmentation in melanoma determines its progression, metastasis, and prognosis, its association with inflammatory cytokines remains unclear. Thus, we evaluated the associations between melanoma pigmentation and plasma levels of inflammatory cytokines; furthermore, we investigated the potential variations in this relationship across the primary anatomic sites of melanoma. We enrolled patients with cutaneous melanoma who visited Chonnam National University Hwasun Hospital between January 2021 and December 2021. The anatomical sites of melanoma were categorized as acral and non-acral sites. The degree of pigmentation was quantified using computer software. In total, nine inflammatory cytokines were analyzed, including interleukin (IL)-2, IL-4, IL-5, IL-10, IL-12, IL-13, granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α). This study included 80 melanoma patients. Of these, 53 had acral melanoma and 27 had non-acral melanoma. Overall, plasma concentrations of IL-2, IL-4, IL-5, GM-CSF, and IFN-γ demonstrated significant correlations with diminished pigmentation. Furthermore, in the acral melanoma patients group, plasma concentrations of IL-2, IL-4, IL-5, GM-CSF, IFN-γ, and TNF-α revealed significant correlations with diminished pigmentation. Our results reveal significant associations between melanoma pigmentation and various cytokine levels, particularly in acral melanoma patients; these associations can be influenced by factors related to acral melanoma, such as physical stress or trauma. These correlations may also provide directions for the treatment of acral melanoma.

Comparative Whole-Genome Sequencing Analysis of In-situ and Invasive Acral Lentiginous Melanoma: Markedly Increased Copy Number Gains of GAB2, PAK1, UCP2, and CCND1 are Associated with Melanoma Invasion.

Acral lentiginous melanoma (ALM) is the most common subtype of acral melanoma. Even though recent genetic studies are reported in acral melanomas, the genetic differences between in-situ and invasive ALM remain unclear. We aimed to analyze specific genetic changes in ALM and compare genetic differences between in-situ and invasive lesions to identify genetic changes associated with the pathogenesis and progression of ALM. We performed whole genome sequencing of 71 tissue samples from 29 patients with ALM. Comparative analyses were performed, pairing in-situ ALMs with normal tissues and, furthermore, invasive ALMs with normal and in-situ tissues. Among 21 patients with in-situ ALMs, 3 patients (14.3%) had SMIM14, SLC9B1, FRG1, FAM205A, ESRRA, and ESPN mutations, and copy number (CN) gains were identified in only 2 patients (9.5%). Comparing 13 invasive ALMs with in-situ tissues, CN gains were identified in GAB2 in 8 patients (61.5%), PAK1 in 6 patients (46.2%), and UCP2 and CCND1 in 5 patients (38.5%). Structural variants were frequent in in-situ and invasive ALM lesions. Both in-situ and invasive ALMs had very low frequencies of common driver mutations. Structural variants were common in both in-situ and invasive ALMs. Invasive ALMs had markedly increased CN gains, such as GAB2, PAK1, UCP2, and CCND1, compared with in-situ lesions. These results suggest that they are associated with melanoma invasion.

The EGR1-Artemin Axis in Keratinocytes Enhances the Innervation of Epidermal Sensory Neurons during Skin Inflammation Induced by House Dust Mite Extract from Dermatophagoidesfarinae.

Epidermal hyperinnervation is a critical feature of pruritus during skin inflammation. However, the mechanisms underlying epidermal hyperinnervation are unclear. This study investigates the role of the transcription factor EGR1 in epidermal innervation by utilizing wild-type (Egr1+/+) and Egr1-null (Egr1‒/‒) mice topically applied Dermatophagoides farinae extract from dust mite. Our findings revealed that Egr1‒/‒ mice exhibited reduced scratching behaviors and decreased density of epidermal innervation compared with Egr1+/+ mice. Furthermore, we identified artemin, a neurotrophic factor, as an EGR1 target responsible for Dermatophagoides farinae extract-induced hyperinnervation. It has been demonstrated that Dermatophagoides farinae extract stimulates toll-like receptors in keratinocytes. To elucidate the cellular mechanism, we stimulated keratinocytes with Pam3CSK4, a toll-like receptor 1/2 ligand. Pam3CSK4 triggered a toll-like receptor 1/2-mediated signaling cascade involving IRAK4, IκB kinase, MAPKs, ELK1, EGR1, and artemin, leading to increased neurite outgrowth and neuronal migration. In addition, increased expression of EGR1 and artemin was observed in the skin tissues of patients with atopic dermatitis. These findings highlight the significance of the EGR1-artemin axis in keratinocytes, promoting the process of epidermal innervation and suggesting it as a potential therapeutic target for alleviating itch and pain associated with house dust mite-induced skin inflammation.

BRAF Mutated and Morphologically Spitzoid Tumors, a Subgroup of Melanocytic Neoplasms Difficult to Distinguish From True Spitz Neoplasms.

Drivers of Spitz neoplasms include activating point mutations in HRAS and Spitz-associated genomic fusions. It has become evident that some BRAF -mutated melanocytic neoplasms can morphologically mimic Spitz tumors (STs). These have been termed BRAF mutated and morphologically spitzoid (BAMS). In this study, 17 experts from the International Melanoma Pathology Study Group assessed 54 cases which included 40 BAMS and 14 true STs. The participants reviewed the cases blinded to the genomic data and selected among several diagnostic options, including BAMS, ST, melanoma, and other. A total of 38% of all diagnostic selections in the BAMS cases were for BAMS, whereas 32% were for ST. In 22 of the BAMS cases, the favored diagnosis was BAMS, whereas in 17 of the BAMS cases, the favored diagnosis was ST. Among the 20 cases in the total group of 54 with the highest number of votes for ST, half were BAMS. Of BAMS, 75% had a number of votes for ST that was within the SD of votes for ST seen among true ST cases. There was poor interobserver agreement for the precise diagnosis of the BAMS (kappa = 0.16) but good agreement that these cases were not melanoma (kappa = 0.7). BAMS nevi/tumors can closely mimic Spitz neoplasms. Expert melanoma pathologists in this study favored a diagnosis of ST in nearly half of the BAMS cases. There are BAMS cases that even experts cannot morphologically distinguish from true Spitz neoplasms.

Amelanotic acral melanomas: clinicopathological, BRAF mutation, and KIT aberration analyses.

BACKGROUND: Amelanotic acral melanoma (AAM) is very rare and difficult to diagnose both clinically and pathologically. Complete-type AAM shows no black to brown pigmentation in the lesion, whereas incomplete-type AAM shows focal or subtle pigmentation. AAM has been the subject of few investigations. OBJECTIVES: We analyzed the clinicopathological features, BRAF mutations, and KIT aberrations in 35 Korean AAM cases. METHODS: We included 28 cases of complete-type and 7 cases of incomplete-type AAM. RESULTS: In all, 26 AAMs (45.7%) were located on the feet of patients, 21 of which (82.9%) showed ulceration. Sixteen cases developed in subungual areas. Nodular melanoma was the most common histopathological subtype (63.6%). The most frequent cell types affected were epithelioid and spindled. HMB-45 staining was strongly positive in 66.7% of AAMs; 4 (12.1%) were negative for HMB-45, and 3 of these were complete-type AAMs. Of 33 total patients, BRAF mutations were detected in 2 AAM cases, and KIT aberrations were present in 11 cases (33.3%). Four cases (12.1%), all of which were complete-type AAMs, had KIT mutations. KIT aberrations were weakly correlated with c-kit staining. Twenty patients were TNM stage I or II, and mean survival was 30.14 ± 4.54 months. LIMITATIONS: The study is limited by the small number of patients. CONCLUSION: Physicians should be aware of rare and hard-to-diagnose AAMs. We expect that tyrosine kinase inhibitors would be effective for KIT-mutated patients with complete-type AAMs.

Nasal tip cutaneous metastases secondary to lung carcinoma: three case reports and a review of the literature.

Cutaneous metastatic carcinoma of the nose is a rare presentation associated with lung cancer. We report here 3 cases of cutaneous metastatic carcinoma of the nose that originated from lung cancer. Two men, age 61 and 76 years, with lung cancers were referred for evaluation of a tumour on the tip of the nose. The third patient, a 57-year-old man, had developed a rosacea-like tumour on the tip of the nose; although he had no history of internal cancer, whole-body positron-emission tomography-computed tomography revealed a primary lung cancer. Skin biopsies of all 3 cases showed metastatic squamous cell carcinoma, and all primary lung cancers were squamous cell carcinomas. Only 3 patients are described here, and further reports are needed to substantiate this interesting phenomenon. When an elderly patient presents to dermatology with a tumour on the nose with or without known internal cancer, it is necessary to approach the diagnosis with caution.

First Case of Atypical, Generalized Skin Rash after Transarterial Chemoembolization in a Patient with Hepatocellular Carcinoma.

Transarterial chemoembolization (TACE) is a widely used hepatocellular carcinoma (HCC) treatment. Some cases of supraumbilical skin rash after TACE in patients with HCC have been reported. To the best of the authors' knowledge, there are no reports on atypical, generalized rashes caused by doxorubicin systemic absorption after TACE. This paper presents the case of a 64-year-old male with HCC who developed generalized macules and patches one day after a successful TACE procedure. A histology examination of a skin biopsy of a dark reddish patch on the knee revealed severe interface dermatitis. He was treated with a topical steroid, and all skin rashes improved within a week with no side effects. This report presents this rare case with a literature review on skin rash after TACE.

Risk factors for sentinel lymph node metastasis in Korean acral and non-acral melanoma patients.

Breslow thickness, ulceration, and mitotic rate are well-known prognostic factors for sentinel lymph node (SLN) metastasis in cutaneous melanoma. We investigated risk factors, including especially the degree of pigmentation, for SLN metastasis in Korean melanoma patients. We enrolled 158, composed of Korean 107 acral and 51 non-acral melanoma patients who underwent SLN biopsy. Clinicopathologic features such as Breslow thickness, ulceration, mitotic rate, and the degree of pigmentation were evaluated. The recurrence-free survival (RFS) rate and date of recurrence were determined. Fifty-four patients (34.2%) had a positive SLN biopsy result. In a multivariate analysis, Breslow thickness (odds ratio [OR] 1.93; 95% confidence interval [CI], 1.12-3.47; p = .022) and heavy pigmentation (OR 13.14; 95% CI, 2.96-95.20, p = .002) were associated with SLN metastasis. Positive SLN patients had a higher rate of loco-regional and/or distant recurrence (hazard ratio 6.32; 95% CI, 3.39-11.79; p < .001). Heavy pigmentation was associated with poor RFS. Heavy pigmentation is an independent predictor of SLN metastasis in both acral and non-acral melanoma. Our results suggest the need for in-depth SLN evaluation of cutaneous melanoma patients with heavy pigmentation and provide clinicians with important information for determining patient prognosis.

Epidemiology and survival analysis of Merkel cell carcinoma in South Korea: a nationwide, multicenter retrospective study.

BACKGROUND: Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer, of which most research has been conducted in Caucasians. Therefore, the clinicopathological features and prognosis of Merkel cell carcinoma in Asians are still scarce. The aim of this study is to investigate the epidemiology and survival of MCC in South Korea and provide representative information regarding MCC in Asia. METHODS: This was a retrospective, nationwide, multicenter study conducted in 12 centers across South Korea. Patients with pathologically proven MCC were included in the study. The clinicopathological features and clinical outcomes of the patients were investigated. Overall survival (OS) was analyzed using the Kaplan-Meier method, and independent prognostic factors were identified using Cox regression analysis. RESULTS: A total of 161 patients with MCC were evaluated. The mean age was 71 years with a female predominance. OS was significantly different among the stages. Among clinicopathological features, multivariate Cox regression analysis demonstrated that only the stage at diagnosis was associated with poorer overall survival. CONCLUSIONS: The results of our study suggest that the incidence of MCC was higher in females than in males and that there was a higher rate of local disease at the time of diagnosis. Among the variable clinicopathological features, disease stage at diagnosis was the only significant prognostic factor for MCC in South Korea. The findings of this nationwide, multicenter study suggest that MCC has distinct features in South Korea compared with other countries.