NECTIN4-targeted antibody-drug conjugate is a potential therapeutic option for extramammary Paget disease.

Extramammary Paget disease (EMPD) is a rare skin cancer mainly found in areas rich in apocrine sweat glands. Since the effective treatments for advanced and/or metastasized EMPD are limited, there is an urgent need to develop novel therapeutic approaches. Nectin cell adhesion molecule 4 (NECTIN4) is highly expressed in cancers and considered to be a promising therapeutic target. NECTIN4 is also expressed in EMPD, but its role and the efficacy of NECTIN4-targeted therapy in EMPD remain unclear. This study investigated the potential of NECTIN4 as a novel therapeutic target for EMPD. NECTIN4 expression was immunohistochemically analysed in EMPD patients' primary (118 samples) and metastatic (21 samples) lesions. Using an EMPD cell line, KS-EMPD-1, the effects of NECTIN4 inhibition on cell proliferation and migration were investigated. NECTIN4 was expressed in primary and metastatic EMPD lesions, and the H-score of NECTIN4 staining was significantly higher in metastatic lesions than in primary ones. Knockdown of NECTIN4 significantly inhibited cell proliferation and affected cell migration. The cytotoxic effects of NECTIN4-targeted antibody-drug conjugate (ADC) were further evaluated, revealing a significant decrease in EMPD cell viability. In conclusion, NECTIN4 is a potential therapeutic target and NECTIN4-targeted ADC is promising as a therapeutic option for EMPD.

FOXM1: a new therapeutic target of extramammary Paget disease.

Extramammary Paget disease (EMPD) is a rare skin cancer that primarily affects older individuals predominantly in areas with apocrine sweat glands. Although most early EMPD lesions are indolent, patients with metastatic EMPD have a poor prognosis due to the lack of effective systemic treatment. In this study, we investigated the role of forkhead box M1 (FOXM1), a potent transcription factor, in EMPD and assessed the potential of FOXM1 as a therapeutic target. Immunohistochemistry of 112 primary and 17 metastatic EMPD samples revealed that FOXM1 expression increased with tumor progression. Patients in whom FOXM1 was expressed in more than 10% of tumor cells had significantly shorter disease-specific survival than the other patients (p = 0.0397). In in vitro studies using our newly established EMPD cell line, KS-EMPD-1, we found high expression of FOXM1. Knockdown of FOXM1 impaired tumor cell viability, migration, and invasion. Inhibition of FOXM1 using thiostrepton also reduced tumor cell viability in a dose-dependent manner. These findings suggest that FOXM1 is a promising therapeutic target for patients with EMPD.

A real-world study on the safety profile of extended-interval dosing of immune checkpoint inhibitors for melanoma: a single-center analysis in Japan.

Background: Anti-programmed death-1 (PD-1) antibodies are the mainstay for the treatment of unresectable or high-risk melanoma. However, real-world data on the safety profile of their extended-interval doses (EDs) are limited, particularly in Asian patients with melanoma. Materials and methods: In this single-center retrospective study, we analyzed the risks of immune-related adverse events (irAEs) among 71 Japanese patients (36 males; mean age, 65.0 years) who received anti-PD-1 monotherapy for melanoma at our institute. Patients who were administered ipilimumab prior to anti-PD-1 monotherapy were excluded. Patients were divided into three groups: canonical-interval dose (CD) group (n = 50, body weight-based dosing or 240 mg Q2W for nivolumab and body weight-based dosing or 200 mg Q3W for pembrolizumab), ED group (n = 14, 480 mg Q4W for nivolumab and 400 mg Q6W for pembrolizumab), and dose-switch (DS) group (n = 7, upfront CD followed by ED). Results: The CD group received nivolumab more frequently in the metastatic setting. There were no significant differences in baseline characteristics among the three groups, including in sex, age, primary tumor site, tumor subtype, and follow-up period. irAEs occurred in 36.6% (26 patients) of all patients (32.0% of the CD group, 35.7% of the ED group, and 71.4% of the DS group), while severe (grade ≥ 3) irAEs occurred in only two patients, both of whom were in the CD group. Most of the irAEs occurred during the first 6 months of anti-PD-1 therapy and, interestingly, all of the irAEs in the DS group occurred before the switch (during the CD). There was no significant difference among the three groups in the probability of irAE estimated by the Kaplan-Meier method. Conclusion: These findings may highlight the safety of ED of anti-PD-1 monotherapy in the treatment of Asian patients with melanoma.

KS-EMPD-1: a novel cell line of primary extramammary Paget's disease.

Extramammary Paget's disease (EMPD) is a rare skin cancer that mainly occurs in apocrine sweat gland-rich areas in elderly people. The prognosis of metastatic EMPD is unfavorable because of the lack of fully effective systemic therapies. However, the difficulty in establishing a model of EMPD has hampered basic research for exploring its pathogenesis and optimal treatments. Here, we established for the first time an EMPD cell line (named KS-EMPD-1) from a primary tumor on the left inguinal region of an 86-year-old Japanese male. The cells were successfully maintained for more than 1 year, with a doubling time of 31.2 ± 0.471 h. KS-EMPD-1 exhibited constant growth, spheroid formation, and invasiveness, and was confirmed to be identical to the original tumor by short tandem repeat analyses, whole exome sequencing, and immunohistochemistry (CK7+CK20-GCDFP15+). Western blotting of the cells revealed the protein expression of HER2, NECTIN4, and TROP2, which have recently attracted attention as potential therapeutic targets for EMPD. KS-EMPD-1 was highly sensitive to docetaxel and paclitaxel on chemosensitivity test. The KS-EMPD-1 cell line is a promising resource for basic and preclinical research on EMPD to better define the tumor characteristics and treatment strategy of this rare cancer.

Nail Apparatus Melanoma: Current Management and Future Perspectives.

Nail apparatus melanoma (NAM) is a rare type of cutaneous melanoma that belongs to the acral melanoma subtype. NAM is managed principally in accordance with the general treatment for cutaneous melanoma, but there is scarce evidence in support of this in the literature. Acral melanoma is genetically different from non-acral cutaneous melanoma, while recently accumulated data suggest that NAM also has a different genetic background from acral melanoma. In this review, we focus on recent advances in the management of NAM. Localized NAM should be surgically removed; amputation of the digit and digit-preserving surgery have been reported. Sentinel lymph node biopsy can be considered for invasive NAM for the purpose of accurate staging. However, it is yet to be clarified whether patients with metastatic sentinel lymph nodes can be safely spared completion lymph node dissection. Similar to cutaneous melanoma, immune checkpoint inhibitors and BRAF/MEK inhibitors are used as the first-line treatment for metastatic NAM, but data on the efficacy of these therapies remain scarce. The therapeutic effects of immune checkpoint inhibitors could be lower for NAM than for cutaneous melanoma. This review highlights the urgent need to accumulate data to better define the optimal management of this rare melanoma.

Human epidermal growth factor receptor 3 serves as a novel therapeutic target for acral melanoma.

Acral melanoma (AM) is a rare, life-threatening skin cancer. Since AM bears unique features, existing therapies for other types of malignant melanomas have limited effects and the establishment of effective treatments for AM is strongly desired. Human epidermal growth factor receptor 3 (HER3) is a receptor tyrosine kinase that is frequently elevated in tumors and contributes to tumor progression, so it is considered a promising therapeutic target for tumors. This study was established to evaluate the potential of HER3-targeted therapy to treat AM by investigating the expression and function of HER3. HER3 expression was immunohistochemically analyzed in AM lesions of 72 patients and in AM cell lines. To investigate function of HER3, effects of HER3 inhibition on cell proliferation, apoptosis/survival, anchorage-independent growth, and underlying signals were assessed. HER3 was expressed in patients' AM tissues with various intensities and HER3 expression was significantly correlated with patient's disease-free survival. In vitro analyses revealed that HER3 is more highly expressed in AM cells than in normal epidermal melanocytes. AM cells were also shown to be sensitive to the cytotoxic part of a HER3-targeted antibody-drug conjugate. Inhibition of HER3 did not affect cell proliferation, whereas it decreased the anchorage-independent growth of AM cells likely through affecting the nuclear translocation of Yes-associated protein. It is implied that HER3 may serve as a novel therapeutic target for AM.

TRPM1 promotes tumor progression in acral melanoma by activating the Ca2+/CaMKIIδ/AKT pathway.

INTRODUCTION: Acral melanoma is a predominant and aggressive subtype of melanoma in non-Caucasian populations. There is a lack of genotype-driven therapies for over 50% of patients. TRPM1 (transient receptor potential melastatin 1), a nonspecific cation channel, is mainly expressed in retinal bipolar neurons and skin. Nonetheless, the function of TRPM1 in melanoma progression is poorly understood. OBJECTIVES: We investigated the association between TRPM1 and acral melanoma progression and revealed the molecular mechanisms by which TRPM1 promotes tumor progression and malignancy. METHODS: TRPM1 expression and CaMKII phosphorylation in tumor specimens were tested by immunohistochemistry analysis and scored by two independent investigators. The functions of TRPM1 and CaMKII were assessed using loss-of-function and gain-of-function approaches and examined by western blotting, colony formation, cell migration and invasion, and xenograft tumor growth assays. The effects of a CaMKII inhibitor, KN93, were evaluated using both in vitro cell and in vivo xenograft mouse models. RESULTS: We revealed that TRPM1 protein expression was positively associated with tumor progression and shorter survival in patients with acral melanoma. TRPM1 promoted AKT activation and the colony formation, cell mobility, and xenograft tumor growth of melanoma cells. TRPM1 elevated cytosolic Ca2+ levels and activated CaMKIIδ (Ca2+/calmodulin-dependent protein kinase IIδ) to promote the CaMKIIδ/AKT interaction and AKT activation. The functions of TRPM1 in melanoma cells were suppressed by a CaMKII inhibitor, KN93. Significant upregulation of phospho-CaMKII levels in acral melanomas was related to increased expression of TRPM1. An acral melanoma cell line with high expression of TRPM1, CA11, was isolated from a patient to show the anti-tumor activity of KN93 in vitro and in vivo. CONCLUSIONS: TRPM1 promotes tumor progression and malignancy in acral melanoma by activating the Ca2+/CaMKIIδ/AKT pathway. CaMKII inhibition may be a potential therapeutic strategy for treating acral melanomas with high expression of TRPM1.

NECTIN4 expression in sebaceous and sweat gland carcinoma

Background: Sebaceous carcinoma and sweat gland carcinoma (malignant tumours with apocrine and eccrine differentiation) are rare malignant adnexal tumours that differentiate toward sebaceous glands and eccrine and apocrine glands, respectively. Because of the rarity of these malignancies, standard treatments for advanced disease have yet to be established. The outcomes of patients with systemic metastasis remain poor, highlighting the need for novel treatment strategies. Nectin cell adhesion molecule 4 (NECTIN4) and its antibody-drug conjugate, enfortumab vedotin, have attracted attention as potential treatments for solid tumours. Objectives: To examine the potential use of NECTIN4-target therapy for sebaceous and sweat gland carcinoma. Materials & Methods: We immunohistochemically investigated NECTIN4 expression in 14 sebaceous carcinoma samples and 18 sweat gland carcinoma samples, and examined whether NECTIN4-targeted therapy could be applied to these cancers. Results: We found strong and frequent expression of NECTIN4 in both cancers. All tumours exhibited positive staining at least in a part of the lesion, and the mean H-score, a semiquantitative score ranging from 0 to 300, was 259.4 for sebaceous carcinoma and 253.1 for sweat gland carcinoma. Conclusion: Our results suggest that both sebaceous carcinoma and sweat gland carcinoma could be potentially treated with NECTIN4-targeted antibody-drug conjugates, such as enfortumab vedotin.

TROP2 Expression in Sebaceous and Sweat Gland Carcinoma.

Sebaceous carcinoma and sweat gland carcinoma (malignant tumors with apocrine and eccrine differentiation) are rare malignant skin adnexal tumors that differentiate toward sebaceous gland and eccrine and apocrine glands, respectively. Owing to the rarity of these carcinomas, standard treatments for advanced disease have not been established. Because the prognosis of patients with systemic metastasis is poor, a new treatment for these diseases is eagerly desired. Trophoblast cell surface antigen 2 (TROP2) and sacituzumab govitecan, an antibody-drug conjugate of TROP2, have attracted attention in the treatment of various solid tumors. In the current study, we immunohistochemically investigated TROP2 expression in 14 sebaceous carcinoma and 18 sweat gland carcinoma samples and found strong and relatively homogeneous TROP2 staining in both cancer types. The mean Histoscore, a semi-quantitative scoring ranging from 0 (negative) to 300, was 265.5 in sebaceous carcinoma and 260.0 in sweat gland carcinoma. These observations directly suggest that both sebaceous carcinoma and sweat gland carcinoma could be potentially treated with TROP2-targeted antibody-drug conjugates such as sacituzumab govitecan.

CDK4: A Novel Therapeutic Target for Extramammary Paget's Disease.

BACKGROUND: The outcome of extramammary Paget's disease (EMPD) is poor when it progresses to metastasis because of the lack of effective systemic therapies. Recently, CDK4-targeted therapy has attracted attention as a potential therapeutic target for some cancers. The aim of this study was to analyze the impact of CDK4 expression on the survival of patients with EMPD. METHODS: We retrospectively reviewed 110 patients with EMPD. We conducted immunohistochemical analysis of CDK4 and cyclin D1 expression, and assessed the association between their expression and survival. RESULTS: Most EMPD lesions (108/110, 98.2%) were positive for CDK4 staining and there was a positive correlation between CDK4 expression and cyclin D1 expression (r = 0.54, p < 0.001). Tumor thickness (p = 0.0003) and the presence of regional lymph node metastasis (p = 0.015) were significantly associated with high CDK4 expression. Regarding invasive EMPD, the multivariate analysis did not show the correlation between the expression of CDK4/cyclin D1 and survival outcomes (HR: 3.14, p = 0.14). CONCLUSION: The overexpression of CDK4 was identified as a major risk factor for disease progression. CDK4-targeted therapy could thus be a novel treatment option for unresectable EMPD.

Trop2 Expression in Extramammary Paget's Disease and Normal Skin.

Extramammary Paget's disease (EMPD) is a rare skin cancer arising in the apocrine gland-rich areas. Most EMPD tumors are dormant, but metastatic lesions are associated with poor outcomes owing to the lack of effective systemic therapies. Trophoblast cell surface antigen 2 (Trop2), a surface glycoprotein, has drawn attention as a potential therapeutic target for solid tumors. Sacituzumab govitecan, an antibody-drug conjugate of Trop2, has recently entered clinical use for the treatment of various solid cancers. However, little is known about the role of Trop2 in EMPD. In this study, we immunohistochemically examined Trop2 expression in 116 EMPD tissue samples and 10 normal skin tissues. In normal skin, Trop2 was expressed in the epidermal keratinocytes, inner root sheaths, and infundibulum/isthmus epithelium of hair follicles, eccrine/apocrine glands, and sebaceous glands. Most EMPD tissues exhibited homogeneous and strong Trop2 expression, and high Trop2 expression was significantly associated with worse disease-free survival (p = 0.0343). These results suggest the potential use of Trop2-targeted therapy for EMPD and improve our understanding of the skin-related adverse effects of current Trop2-targeted therapies such as sacituzumab govitecan.

Mucosal Invasion, but Not Incomplete Excision, Has Negative Impact on Long-Term Survival in Patients With Extramammary Paget's Disease.

BACKGROUND: Extramammary Paget's disease (EMPD) sometimes spreads from the skin to mucosal areas, and curative surgical excision of these areas is challenging. The aim of this study is to analyze the impact of mucosal involvement and surgical treatment on the survival of patients with EMPD. METHODS: We conducted a retrospective review of 217 patients with EMPD. We also assessed the associations between tumor involvement in boundary areas (anal canal, external urethral meatus, vaginal introitus), prognostic factors, and survival in 198 patients treated with curative surgery. RESULTS: Of 217 patients, 75 (34.6%) had mucosal boundary area involvement. Lesions in these areas were associated with frequent lymphovascular invasion (p = 0.042), lymph node metastasis (p = 0.0002), incomplete excision (p < 0.0001), and locoregional recurrence (p < 0.0001). Boundary area involvement was an independent prognostic factor associated with disease-specific survival, per multivariate analysis (HR: 11.87, p = 0.027). Incomplete excision was not significantly correlated with disease-specific survival (HR: 1.05, p = 0.96). CONCLUSION: Boundary area tumor involvement was a major risk factor for incomplete excision, local recurrence, and poor survival outcomes. However, incomplete removal of primary tumors was not significantly associated with poor prognosis. A less invasive surgical approach for preserving anogenital and urinary functions may be acceptable as the first-line treatment for resectable EMPD.

The Outcome of Chemotherapy for Metastatic Extramammary Paget's Disease.

The efficacy and survival impact of conventional chemotherapies for metastatic extramammary Paget's disease (EMPD) have not been fully elucidated. This study examined the long-term outcome of chemotherapy for this indication. We conducted a retrospective review of 21 patients with distant metastatic EMPD (14 patients treated with chemotherapy and 7 patients treated without chemotherapy). The response rate of chemotherapy and patient survival were statistically analyzed. Among the 14 patients treated with chemotherapy, 12, 1, and 1 patient received docetaxel, paclitaxel, and low-dose 5-fluorouracil plus cisplatin, respectively, as the first-line treatment. The response rate was 50.0% (7/14), and the disease control rate was 64.3% (9/14). The median progression-free survival (PFS) and overall survival (OS) were 16.8 and 27.9 months, respectively. Multivariate analyses revealed that chemotherapy was a significant factor for prolonged PFS (hazard ratio (HR) 0.22, p = 0.038) but not for OS (HR = 1.71, p = 0.54). Ten patients (71.4%) had severe (grade 3 or 4) hematological adverse events. Although conventional chemotherapy improved PFS, we failed to show a significantly improved OS. Considering the frequent adverse events of conventional chemotherapy, targeted therapy may become a mainstay for the treatment of metastatic EMPD.

BRAF Heterogeneity in Melanoma.

OPINION STATEMENT: In the era of molecular targeted therapy, the accurate detection of BRAF mutation in melanoma has become increasingly important. With the advances of molecular analyses and immunohistochemistry, the presence of BRAF mutational heterogeneity in melanoma has been widely recognized. Although most patients with melanoma have a homogeneous BRAF mutation status because the BRAF mutation occurs at an early stage of melanoma development and acts as a driver gene mutation, BRAF mutational heterogeneity does exist, among different tumor sites of a single patient (intertumor heterogeneity) and/or even within a single tumor (intratumor heterogeneity). To summarize the published reports, about 10% of melanoma patients may show intertumorally discordant BRAF status and about 15% of BRAF-mutated melanomas may have intratumor BRAF heterogeneity, although the reported results vary strikingly among the studies and methods used. Considering the BRAF heterogeneity of melanoma, a single biopsy from a single tumor may not be sufficient to uncover the entire BRAF status of a patient. Multiple samples from different sites may be preferable to assess the indication of BRAF/MEK inhibitors, as recommended by the current clinical guidelines. The impact of BRAF heterogeneity on patient survival or the response to treatment with BRAF/MEK inhibitors is an interesting issue, but requires further investigation.

NECTIN4 Expression in Extramammary Paget's Disease: Implication of a New Therapeutic Target.

Extramammary Paget's disease (EMPD) is a rare skin cancer arising in the anogenital area. Most EMPD tumors remain dormant as in situ lesions, but the outcomes of patients with metastatic EMPD are poor because of the lack of effective systemic therapies. Nectin cell adhesion molecule 4 (NECTIN4) has attracted attention as a potential therapeutic target for some cancers. Urothelial cancer is one such cancer, and clinical trials of enfortumab vedotin, a drug-conjugated anti-NECTIN4 antibody, are ongoing. However, little is known regarding the role of NECTIN4 in EMPD. In this study, we conducted immunohistochemical analysis of NECTIN4 expression in 110 clinical EMPD samples and normal skin tissue. In normal skin, positive signals were observed in epidermal keratinocytes (particularly in the lower part of the epidermis), eccrine and apocrine sweat glands, inner and outer root sheaths, and matrix of the hair follicles. The most EMPD lesions exhibited strong NECTIN4 expression, and high NECTIN4 expression was significantly associated with increased tumor thickness, advanced TNM stage, and worse disease-specific survival. These results support the potential use of NECTIN4-targeted therapy for EMPD. Our report contributes to the better understanding of the pathobiology of NECTIN4 in the skin and the skin-related adverse effects of NECTIN4-targeted therapy.

Narrow-Margin Excision for Invasive Acral Melanoma: Is It Acceptable?

In this retrospective review of 100 patients with primary invasive acral melanoma, we examined whether narrow-margin excision is warranted for acral melanoma. Patients treated with surgical margins recommended by the National Comprehensive Cancer Network (R-group) were compared to those treated with narrow margins (N-group). A total of 65 patients underwent narrow-margin excision. Positive margin status or local recurrence rarely occurred regardless of the excision margins, whereas fatal events frequently occurred, particularly among the patients with T4 melanoma. The mortality rates of N- and R-group with T1-3 melanomas were similar (1.36 and 1.28 per 100 person-years, respectively). However, patients with T4 melanoma treated with narrow-margin excision had a higher mortality rate (11.44 vs. 5.03 per 100 person-years). Kaplan-Meier analyses showed a worse prognosis in the N-group (p = 0.045) but this group had thicker Breslow thickness (4.21 mm vs. 2.03 mm, p = 0.0013). A multivariate analysis showed that Breslow thickness was an independent risk factor, but surgical margin was not a risk factor for melanoma-specific survival or disease-free survival. In conclusion, although we could not find a difference between the narrow-margin excision and recommended-margin excision in this study, we suggest following current recommendations of guidelines. Our study warrants the prospective collection of data on acral melanoma to better define the prognosis of this infrequent type of melanoma.

Immunohistochemical BRAF V600E Expression and Intratumor BRAF V600E Heterogeneity in Acral Melanoma: Implication in Melanoma-Specific Survival.

Acral melanoma, a distinct form of cutaneous melanoma originating in the glabrous skin of the palms, soles, and nail beds, has a different genetic background from other subtypes of cutaneous melanoma. The roles of oncogenic BRAF mutations of acral melanoma in pathogenesis and patient outcomes have not been fully elucidated. We retrieved a total of 112 patients with primary acral melanoma and checked their BRAF V600E status using immunohistochemical staining of VE1 antibody. Among these cases, 21 acral melanoma samples (18.8%) showed positive BRAF V600E staining, and of those, 11 samples (9.8%) showed a heterogeneous staining pattern, with a mixture of VE1-positive and VE1-negative cells. BRAF V600E positivity was significantly associated with thicker melanoma (p = 0.0015). There was no significant difference in clinicopathological factors between homogeneous and heterogeneous VE1-positive acral melanoma. Both patients with BRAF V600E-positive acral melanoma and those with heterogeneous BRAF V600E had significantly shorter melanoma-specific survival than those with BRAF V600E-negative melanoma in Kaplan-Meier analysis (p = 0.0283 and p = 0.0065, respectively). These findings provide novel insights into the pathobiology of acral melanoma.

Intra- and Inter-Tumor BRAF Heterogeneity in Acral Melanoma: An Immunohistochemical Analysis.

The current development of BRAF inhibitors has revolutionized the treatment of unresectable melanoma. As the potential heterogeneity of BRAF mutations in melanoma has been reported, accurate detection of BRAF mutations are important. However, the genetic heterogeneity of acral melanoma-a distinct type of melanoma with a unique genetic background-has not fully been investigated. We conducted a retrospective review of our acral melanoma patients. Of the 196 patients with acral melanoma, we retrieved 31 pairs of primary and matched metastatic melanomas. We immunostained the 31 pairs with VE1, a BRAFV600E-mutation-specific monoclonal antibody. Immunohistochemistry with VE1 showed a high degree of sensitivity and specificity for detecting BRAFV600E mutations compared with the real-time polymerase chain reaction method. A total of nine primary (29.0%) and eight metastatic (25.8%) acral melanomas were positive for VE1. In three patients (9.7%), we observed a discordance of VE1 staining between the primary and metastatic lesions. Of note, VE1 immunohistochemical staining revealed a remarkable degree of intra-tumor genetic heterogeneity in acral melanoma. Our study reveals that VE1 immunostaining is a useful ancillary method for detecting BRAFV600E mutations in acral melanoma and allows for a clear visualization of intra- and inter-tumor BRAF heterogeneity.

The diagnosis and management of extramammary Paget's disease.

INTRODUCTION: Extramammary Paget's disease (EMPD) is a rare neoplastic condition that commonly affects the anogenital area in the elderly. Owing to its low incidence, limited data regarding EMPD's diagnosis and treatment have been available. This review article aims to explore the current knowledge of EMPD to improve the management of this disease. Areas covered: This review outlines the diagnosis and management of EMPD. Articles on this issue that had been published in PubMed were identified and surveyed. We provide an overview of the reported studies, focusing on the recent advances in this field. Expert commentary: A new TNM staging system specific for EMPD has been proposed in Japan; the T category was classified by tumor thickness and lymphovascular invasion, the N category by the number of metastatic lymph nodes, and the M category by systemic metastases. As new diagnostic tools for EMPD, dermoscopy and reflectance confocal microscopy have emerged. Recent reports about Mohs micrographic surgery, mapping biopsy, radiation therapy, photodynamic therapy, topical imiquimod, conventional chemotherapy, and targeted therapy are also discussed. Despite the increasing publications of EMPD, limited information on this condition is available and the accumulation of more data is required.

Evaluation of mapping biopsies for extramammary Paget disease: A retrospective study.

BACKGROUND: Extramammary Paget disease (EMPD) sometimes shows an ill-defined border and an unexpectedly extended tumor spread beyond the clinical borders. Mapping biopsy is 1 approach for complete surgical removal, but its efficacy has remained controversial. OBJECTIVE: We sought to evaluate mapping biopsies for EMPD. METHODS: We performed a retrospective review of 133 patients with 150 primary EMPD lesions. We histopathologically examined 1182 skin biopsy specimens (975 from mapping biopsy and 207 from lesional biopsy). RESULTS: Only 1.6% of mapping biopsy specimens from well-defined EMPD (13 of 810) were positive. Moreover, 4.6% of mapping biopsy specimens from ill-defined EMPD (8 of 165) were positive, whereas all specimens taken from sites 2 cm or more from the clinical border were negative. For both well-defined and ill-defined EMPD, there was no significant difference in the margin status of surgical resection regardless of mapping biopsy. LIMITATIONS: This was a retrospective study. CONCLUSIONS: Mapping biopsies are unnecessary for well-defined EMPD or when 2-cm margins can be achieved, whereas surgical removal with predetermined margins (1 cm for well-defined EMPD and 2 cm for ill-defined EMPD) appears to be safe. Mapping biopsies can be considered when shortening of the safe surgical margin to less than 2 cm is required in ill-defined EMPD.