Stem cell spreading dynamics intrinsically differentiate acral melanomas from nevi.

Early differential diagnosis between malignant and benign tumors and their underlying intrinsic differences are the most critical issues for life-threatening cancers. To study whether human acral melanomas, deadly cancers that occur on non-hair-bearing skin, have distinct origins that underlie their invasive capability, we develop fate-tracing technologies of melanocyte stem cells in sweat glands (glandular McSCs) and in melanoma models in mice and compare the cellular dynamics with human melanoma. Herein, we report that glandular McSCs self-renew to expand their migratory progeny in response to genotoxic stress and trauma to generate invasive melanomas in mice that mimic human acral melanomas. The analysis of melanocytic lesions in human volar skin reveals that genetically unstable McSCs expand in sweat glands and in the surrounding epidermis in melanomas but not in nevi. The detection of such cell spreading dynamics provides an innovative method for an early differential diagnosis of acral melanomas from nevi.

Long-term efficacy and safety of bexarotene for Japanese patients with cutaneous T-cell lymphoma: The results of a phase 2 study (B-1201).

The present study (B-1201 clinical trial) was conducted as a multicenter, open-label, single-arm phase II study to evaluate the long-term safety, tolerability and efficacy of bexarotene. This study enrolled 10 Japanese adults aged more than 20 years with cutaneous T-cell lymphoma (CTCL) who completed the 24-week study period of the B-1101 trial. The objective response rate (ORR) was 53.8% (95% confidence interval, 25.1-80.8). In the early stage (IB), the ORR was 60% (3/5 cases). In the advanced stage (IIB and IIIA), the ORR was 57.1% (4/7 cases). The median time to response was 58 days (range, 27-168). The median treatment duration was 380 days (range, 33-1674). The median duration of response (DOR) could not be reached during the study period. The longest DOR reached 1618 days at the end of the B-1201 trial. Nine patients (56.3%) in the full analysis set (FAS) population experienced dose reduction of bexarotene. Common drug-related adverse events in the FAS population included hypothyroidism (93.8%), hypertriglyceridemia (81.3%), hypercholesterolemia (81.3%), leukopenia (68.8%) and neutropenia (56.3%). Dose-limiting toxicity (DLT) was present in five (38.5%) of the 13 patients in the 300 mg/m2 cohort. Of the five patients, four developed grade 3 neutropenia and one developed grade 4 hypertriglyceridemia. All DLT cases recovered after the discontinuation of bexarotene. None of the five patients discontinued this trial because of DLT. The B-1201 trial shows the long-term safety of oral bexarotene for Japanese patients with CTCL, despite frequent dose reduction.

Histogenesis of cutaneous malignant melanoma: The vast majority do not develop from melanocytic nevus but arise de novo as melanoma in situ.

It has been considered that most cutaneous malignant melanomas arise from pre-existing melanocytic nevus. Many clinical and histopathological studies seem to support this concept. Dysplastic nevus originally proposed by Clark's group is a key entity of the intermediate lesion between benign nevus and melanoma. The latest edition of the WHO Classification of Skin Tumours (2018) has excluded Clark nevus (dysplastic nevus of mild atypia) from dysplastic nevus, the latter being now classified into the low- and high-grade by the degrees of nuclear atypia. The World Health Organization classification regards dysplastic nevus of both grades as the intermediate lesion between common acquired nevus and the radial growth-phase melanoma. An extensive genetic study recently performed by Bastian's group indicated the existence of intermediate lesions between nevus and melanoma. In spite of these findings, some investigators doubt the concept of the intermediate lesions including dysplastic nevus and insist that the majority of melanomas arise de novo as melanoma in situ, not in association with a preceding nevus. The concept of de novo genesis of melanoma may be supported by a recent meta-analysis study revealing that 71% of melanomas likely arose de novo and 29% from pre-existing nevus. In this review article, from the viewpoint of de novo genesis of melanoma, the author critically discusses the relevant findings of melanoma genesis and proposes a new framework to interpret the morphological and genetic data alternatively. Clarification of the oncogenic process of melanoma has great impact not only on clinical dermatology but also on basic oncology.

Poromas with large lumens histopathologically mimicking syringocystadenoma papilliferum: Report of three cases.

We report on three patients exhibiting tumours with exophytic pedunculated structures with eroded surfaces. All cases showed the basic histopathological features of poroma accompanied by large, invaginated ductal structures lined by multiple layers of columnar or cuboidal cells. The columnar cells of invaginated ductal/cystic structures focally exhibited subtle features reminiscent of decapitation secretion along with dense infiltration of plasma cells in the surrounding stroma, mimicking syringocystadenoma papilliferum.

Phase I/II study of the oral retinoid X receptor agonist bexarotene in Japanese patients with cutaneous T-cell lymphomas.

Safety, tolerability, pharmacokinetics and efficacy of bexarotene, a novel retinoid X receptor (RXR)-selective retinoid, were evaluated in Japanese patients with stage IIB-IVB and relapsed/refractory stage IB-IIA cutaneous T-cell lymphomas (CTCL). This study was conducted as a multicenter, open-label, historically controlled, single-arm phase I/II study. Bexarotene was p.o. administrated once daily at a dose of 300 mg/m2 for 24 weeks in 13 patients, following an evaluation of safety and tolerability for 4 weeks at a dose of 150 mg/m2 in three patients. Eight of 13 patients (61.5%) with an initial dose of 300 mg/m2 met the response criteria using the modified severity-weighted assessment tool (mSWAT) at 24 weeks or discontinuation. Dose-limiting toxic effects (DLT) were present in four of 13 patients (31%) at a dose of 300 mg/m2 : two neutropenia, one abnormal hepatic function and one hypertriglyceridemia. No DLT was observed in patients received 150 mg/m2 bexarotene. In the 13 patients at 300 mg/m2 , common drug-related adverse events (AE) included hypothyroidism (92%), hypercholesterolemia (77%), leukopenia or neutropenia (39%), nasopharyngitis or anemia (31%). The treatment-related grade 3 AE included hypertriglyceridemia (4/16 patients, 25%), increased alanine aminotransferase, increased aspartate aminotransferase, dyslipidaemia, leukopenia and neutropenia (1/16 patients, 6%), and one of 16 patients experienced grade 4 hypertriglyceridemia. No patients discontinued bexarotene due to the AE during the study, but dose reduction or suspension was required. Bexarotene was shown to be well tolerated at 300 mg/m2 once daily and effective in Japanese patients with CTCL.

Standardization of terminology in dermoscopy/dermatoscopy: Results of the third consensus conference of the International Society of Dermoscopy.

BACKGROUND: Evolving dermoscopic terminology motivated us to initiate a new consensus. OBJECTIVE: We sought to establish a dictionary of standardized terms. METHODS: We reviewed the medical literature, conducted a survey, and convened a discussion among experts. RESULTS: Two competitive terminologies exist, a more metaphoric terminology that includes numerous terms and a descriptive terminology based on 5 basic terms. In a survey among members of the International Society of Dermoscopy (IDS) 23.5% (n = 201) participants preferentially use descriptive terminology, 20.1% (n = 172) use metaphoric terminology, and 484 (56.5%) use both. More participants who had been initially trained by metaphoric terminology prefer using descriptive terminology than vice versa (9.7% vs 2.6%, P < .001). Most new terms that were published since the last consensus conference in 2003 were unknown to the majority of the participants. There was uniform consensus that both terminologies are suitable, that metaphoric terms need definitions, that synonyms should be avoided, and that the creation of new metaphoric terms should be discouraged. The expert panel proposed a dictionary of standardized terms taking account of metaphoric and descriptive terms. LIMITATIONS: A consensus seeks a workable compromise but does not guarantee its implementation. CONCLUSION: The new consensus provides a revised framework of standardized terms to enhance the consistent use of dermoscopic terminology.

Automated evaluation system of dermoscopic images of longitudinal melanonychia: proposition of a discrimination index for detecting early nail apparatus melanoma.

The prognosis of nail apparatus melanoma is generally poor because of difficulty in early stage diagnosis. Most nail apparatus melanomas occur as longitudinal melanonychia, and criteria and algorithms for dermoscopy diagnosis of longitudinal melanonychia have only recently been proposed. However, as with any clinical diagnosis, the diagnosis based on dermoscopy is to some extent subjective. Our goal is to develop an automated dermoscopic screening system for longitudinal melanonychia and to propose a novel objective and quantitative index for discriminating early nail apparatus melanoma from benign longitudinal melanonychia including melanocytic nevus. We propose an automatically calculated index representing degrees of color variegation in dermoscopic images of longitudinal melanonychia. Dermoscopy images of six cases of early stage nail apparatus melanoma and 25 cases of benign longitudinal melanonychia were analyzed with our screening system and a threshold of melanoma discrimination index was determined. This single melanoma discrimination index diagnosed early nail apparatus melanoma with 100% sensitivity and 92% specificity. The automatically calculated index proposed in the present study is valuable for managing longitudinal melanonychia. The results suggest that the degree of color variegation is essentially different between early nail apparatus melanoma and benign longitudinal melanonychia including melanocytic nevus of the nail apparatus.

A melanocyte--melanoma precursor niche in sweat glands of volar skin.

Determination of the niche for early-stage cancer remains a challenging issue. Melanoma is an aggressive cancer of the melanocyte lineage. Early melanoma cells are often found in the epidermis around sweat ducts of human volar skin, and the skin pigmentation pattern is an early diagnostic sign of acral melanoma. However, the niche for melanoma precursors has not been determined yet. Here, we report that the secretory portion (SP) of eccrine sweat glands provide an anatomical niche for melanocyte-melanoma precursor cells. Using lineage-tagged H2B-GFP reporter mice, we found that melanoblasts that colonize sweat glands during development are maintained in an immature, slow-cycling state but renew themselves in response to genomic stress and provide their differentiating progeny to the epidermis. FISH analysis of human acral melanoma expanding in the epidermis revealed that unpigmented melanoblasts with significant cyclin D1 gene amplification reside deep in the SP of particular sweat gland(s). These findings indicate that sweat glands maintain melanocyte-melanoma precursors in an immature state in the niche and explain the preferential distribution of early melanoma cells around sweat glands in human volar skin.