Diagnosis and treatment of nail melanoma: a review of the clinicopathologic, dermoscopic, and genetic characteristics.

Nail melanoma (NM) is an important differential diagnosis in patients with longitudinal melanonychia. However, diagnosis is often challenging as it is difficult to differentiate from other pigmented nail disorders. The main challenge for diagnosis is obtaining adequate nail matrix biopsy specimens for histopathological assessment. Furthermore, the histopathological changes in the early stages of NM are subtle and contribute to a delay in diagnosis and care. Therefore, the integration of clinical and histopathological analyses is essential. Clinical and dermoscopic features, such as a broadened width of asymmetric bands in an irregular pattern, with multicolour pigmentation, periungual pigmentation, and continuous growth, are features that support the diagnosis of NM. The essential histological features that must be assessed are cellular morphology, architectural features, melanocyte density, and inflammatory changes. The reported mutations in NMs were BRAF (0-43%), NRAS (0-31%), KIT (0-50%), NF1 (0-50%), and GNAQ (0-25%). Surgery is the primary treatment for NM. The recommended treatment for in situ or minimally invasive NM is functional surgery, but cases with suspected bone invasion should be treated with amputation. Targeted therapy and immunotherapy are indicated for advanced stages of NM. This review summarizes the updated guidelines for the diagnosis and treatment of NM.

Developing a predictive model for distinguishing invasive nail unit melanoma from nail unit melanoma in situ.

BACKGROUND: Clinical information that distinguishes invasive nail unit melanoma from nail unit melanoma in situ before surgery would aid physicians in the decision-making process and estimating prognosis. However, limited information is available on the detailed demographic and dermoscopic features of invasive nail unit melanoma and nail unit melanoma in situ for differential diagnosis. OBJECTIVE: This study aimed to investigate the demographic data and dermoscopic features of invasive nail unit melanoma and nail unit melanoma in situ and establish a predictive model for differentiating these two forms of nail unit melanoma. METHODS: A retrospective observational study of ninety-seven patients diagnosed with nail unit melanoma (59 in situ and 38 invasive cases) in four healthcare centres in South Korea (three tertiary referral hospitals and one second referral hospital) from March 2014 to December 2019. RESULTS: A multivariable analysis revealed that ulcer (odds ratio = 21.6, confidence interval = 2.1-219.8, P = 0.009), total melanonychia (odds ratio = 17.6, confidence interval = 3.0-104.0, P = 0.002), nail plate destruction (odds ratio = 10.9, confidence interval = 2.0-59.4, P = 0.006) and polychromia (odds ratio = 5.3, confidence interval = 1.36-20.57, P = 0.016) were distinctive dermoscopic features of invasive nail unit melanoma. A predictive model with scores ranging from 0 to 6 points demonstrated a reliable diagnostic value (C-statistic = 0.902) in differentiating invasive nail unit melanoma from nail unit melanoma in situ. CONCLUSIONS: Invasive nail unit melanoma and nail unit melanoma in situ have different dermoscopic features. A predictive model based on morphologic dermoscopic features could aid in differentiating invasive nail unit melanoma from nail unit melanoma in situ.

Low and high body mass index in hidradenitis suppurativa patients-different subtypes?

INTRODUCTION: Overweight is a well-established risk factor for hidradenitis suppurativa (HS). In this cross-sectional study, we compare HS patients with a high body mass index (BMI) with HS patients with a low BMI to investigate differences in disease characteristics. MATERIALS AND METHOD: Patients were recruited from 17 dermatological centres from four continents. A total of 246 patients with a BMI below 25 were compared to 205 patients with a BMI of above 35. RESULTS: Patients with a high BMI suffered more severe disease (Hurley, physician global assessment, number of areas affected and patient-reported severity (PRS), P < 0.001 for all). There was no difference in smoking (P = 0.783) nor in family history (P = 0.088). In both low and high BMI patients, early onset of HS was a predictor of positive family history (P < 0.001, for each). For low BMI patients, an increase in BMI significantly increased PRS (P < 0.001). For patients with a high BMI, number of pack-years significantly increased PRS (P = 0.001). Cluster analysis of eruption patterns was location specific for low BMI patients but severity specific for high BMI patients. DISCUSSION: Patients with a low and high BMI could represent two clinically different subtypes. We suggest a non-linear relationship between BMI and impact of HS. As patients go from a low BMI patient to a high BMI patient (or from high to low), eruption patterns and risk factors may change.