Assessment of melanoma thickness based on dermoscopy images: an open, web-based, international, diagnostic study.

BACKGROUND: Preoperative assessment of whether a melanoma is invasive or in situ (MIS) is a common task that might have important implications for triage, prognosis and the selection of surgical margins. Several dermoscopic features suggestive of melanoma have been described, but only a few of these are useful in differentiating MIS from invasive melanoma. OBJECTIVE: The primary aim of this study was to evaluate how accurately a large number of international readers, individually as well as collectively, were able to discriminate between MIS and invasive melanomas as well as estimate the Breslow thickness of invasive melanomas based on dermoscopy images. The secondary aim was to compare the accuracy of two machine learning convolutional neural networks (CNNs) and the collective reader response. METHODS: We conducted an open, web-based, international, diagnostic reader study using an online platform. The online challenge opened on 10 May 2021 and closed on 19 July 2021 (71 days) and was advertised through several social media channels. The investigation included, 1456 dermoscopy images of melanomas (788 MIS; 474 melanomas ≤1.0 mm and 194 >1.0 mm). A test set comprising 277 MIS and 246 invasive melanomas was used to compare readers and CNNs. RESULTS: We analysed 22 314 readings by 438 international readers. The overall accuracy (95% confidence interval) for melanoma thickness was 56.4% (55.7%-57.0%), 63.4% (62.5%-64.2%) for MIS and 71.0% (70.3%-72.1%) for invasive melanoma. Readers accurately predicted the thickness in 85.9% (85.4%-86.4%) of melanomas ≤1.0 mm (including MIS) and in 70.8% (69.2%-72.5%) of melanomas >1.0 mm. The reader collective outperformed a de novo CNN but not a pretrained CNN in differentiating MIS from invasive melanoma. CONCLUSIONS: Using dermoscopy images, readers and CNNs predict melanoma thickness with fair to moderate accuracy. Readers most accurately discriminated between thin (≤1.0 mm including MIS) and thick melanomas (>1.0 mm).

Curettage vs. cryosurgery for superficial basal cell carcinoma: a prospective, randomised and controlled trial.

BACKGROUND: Basal cell carcinoma (BCC) is the most common cancer in the world and has a rising incidence. Current guidelines for low-risk BCC including superficial BCC (sBCC) recommend several treatment options including destructive treatment methods, such as cryosurgery with or without prior curettage or curettage and electrodesiccation. Curettage only (i.e. without subsequent cryosurgery or electrodesiccation) is a simple and quick destructive treatment method used for many benign skin lesions but has not been sufficiently evaluated for the treatment of sBCCs. OBJECTIVES: The objective was to compare the effectiveness of curettage vs. cryosurgery for sBCCs in terms of overall clinical clearance rates after 1 year as well as wound healing times. METHODS: A single-centre non-inferiority clinical trial was conducted. Non-facial sBCCs with a diameter of 5-20 mm were randomised to either cryosurgery using one freeze-thaw cycle or curettage. At follow-up visits, treatment areas were evaluated regarding the presence of residual tumour after 3-6 months and recurrence after 1 year. Further, wound healing times were assessed. RESULTS: In total, 228 sBCCs in 97 patients were included in the analysis. At 3-6 months, no residual tumours were seen in any of the treated areas. After 1 year, the clinical clearance rates for curettage and cryosurgery were 95.7% and 100%, respectively (P = 0.060). However, the non-inferiority analysis was inconclusive. Wound healing times were shorter for curettage (4 weeks) compared to cryosurgery (5 weeks; P < 0.0001). Overall, patient satisfaction at 1 year was high. CONCLUSIONS: Both treatment methods showed high clinical clearance rates after 1 year, whilst curettage reduced the wound healing time.

Dermoscopy of porokeratosis: results from a multicentre study of the International Dermoscopy Society.

BACKGROUND: The diagnosis of porokeratosis can be challenging, and knowledge about its dermoscopic features is limited. OBJECTIVES: To describe the dermoscopic features of porokeratosis of Mibelli and disseminated superficial actinic porokeratosis (DSAP) and the frequency of these features in a larger case series. The interobserver concordance was also assessed. METHODS: In this retrospective cohort study, members of the International Dermoscopy Society contributed macroscopic and dermoscopic images of histopathologically verified cases of porokeratosis of Mibelli or DSAP. Three observers independently reviewed the collected images to identify the presence of predefined dermoscopic features. Following this, a consensus meeting was held to agree upon which dermoscopic features were present in each lesion. RESULTS: In total, 78 clinical and dermoscopic images of porokeratoses were collected. The most common dermoscopic feature was keratin rim, which was present in 74 lesions (92.3%). The most common vascular structures were dotted or glomerular vessels which were present in almost half of the cases (48.7%). Other relatively frequent dermoscopic findings were as follows: non-peripheral scales (44.9%), grey-brown dots or pigmentation along the keratin rim (38.5%), and light-brown pigmentation within the keratin rim (33.3%). Shiny white structures and blood spots or erosions along the keratin rim were findings never before described in porokeratosis and were detected in 16.7% and 17.9% of the lesions, respectively. Dermoscopic findings in porokeratosis of Mibelli and DSAP were similar except for fewer blood spots or erosions along the keratin rim and more light-brown pigmentation within the keratin rim in DSAP. The interobserver concordance ranged from 0.44 (moderate) to 0.84 (almost perfect). CONCLUSIONS: The dermoscopic hallmark of porokeratosis is the keratin rim, a finding also allowing for almost perfect interobserver agreement. Pigmentation or erosions along the keratin rim, vascular structures, as well as scales, pigmentation or shiny white structures within the keratin rim are additional dermoscopic clues.

Methotrexate treatment for patients with psoriasis and risk of cutaneous melanoma: a nested case-control study.

BACKGROUND: Cutaneous malignant melanoma (CMM) is a highly immunogenic tumour. Patients with an impaired immune system have an enhanced risk for CMM and a worse prognosis. Methotrexate (MTX) is an anti-inflammatory and immunosuppressive drug frequently used to treat patients with psoriasis. An association between MTX and risk of CMM has previously been demonstrated in patients with rheumatoid arthritis. OBJECTIVES: To investigate whether MTX increases the risk of CMM among patients with psoriasis. METHODS: A nested case-control investigation from a Swedish cohort of patients with psoriasis was conducted. Data were obtained from available Swedish registers and included 395 patients with psoriasis who had previously been cancer-free and had a first CMM in the time period from 1 January 2010 to 31 December 2016. A total of 10 randomly selected cancer-free patients with psoriasis were matched per case with respect to age (same birth year) and sex. The accumulated MTX doses in both groups were obtained. Crude odds ratios (ORs) for the proportion of MTX in the respective group were calculated using conditional logistic regression analyses. RESULTS: Of 395 patients with psoriasis who had CMM, 97 (25%) had filled a prescription of MTX; of 3950 controls, the corresponding number was 954 (24%). In a conditional logistic regression analysis, no association between MTX exposure (ever use) and risk for CMM was observed (OR 1·0, 95% confidence interval 0·8-1·3). Moreover, no indication of a dose-response association was observed. CONCLUSIONS: In this Swedish nested case-control study, the use of MTX was not associated with an enhanced risk for CMM. These findings are reassuring for dermatologists in everyday clinical practice. What is already known about this topic? Methotrexate (MTX) treatment has been linked to an increased risk for cutaneous malignant melanoma (CMM) in an Australian cohort of patients with rheumatoid arthritis. In a previous retrospective Swedish cohort investigation, patients who had exclusively been prescribed MTX by a dermatologist did not have an enhanced risk for CMM compared with MTX-unexposed individuals. Nevertheless, this cohort did not specifically include patients with psoriasis. What does this study add? This Swedish nested case-control investigation included 395 previously cancer-free patients with psoriasis who had CMM (cases) and 3950 matched cancer-free patients with psoriasis (controls). No association between MTX exposure and risk for CMM in patients with psoriasis was observed. The results are reassuring for dermatologists using MTX to treat patients with psoriasis. Linked Comment: Haugaard and Egeberg. Br J Dermatol 2020; 183:608-609.

Methotrexate treatment and risk for cutaneous malignant melanoma: a retrospective comparative registry-based cohort study.

BACKGROUND: Methotrexate (MTX) is frequently used as an immunosuppressive drug in inflammatory diseases. It is controversial and it has not been thoroughly investigated whether MTX increases the risk of cutaneous malignant melanoma (CMM). OBJECTIVES: The aim of the present study was to investigate whether MTX exposure increases the risk for CMM. METHODS: A retrospective cohort study was conducted using statistics from the National Board of Health and Welfare. All patients over 18 years in the time period August 2005 to December 2014 that were dispensed MTX from Swedish pharmacies were registered (n = 101 966). For every MTX-exposed patient, five age- and sex-matched patients who had been dispensed a random drug other than MTX during the same time period were randomly selected (n = 509 279). The lists were matched with the Swedish Cancer Registry. RESULTS: Overall, a small but statistically significant (P < 0·001) risk increase for CMM was observed in MTX-exposed patients compared with patients without MTX exposure. The Kaplan-Meier estimates for the 5-year risk of CMM was 0·48% [95% confidence interval (CI) 0·43-0·53] in the MTX-exposed group and 0·41% (95% CI 0·39-0·43) in the MTX-unexposed group. However, in a subgroup analysis, the difference between the groups was preserved only in women older than 70 years at treatment start. Moreover, there was no significant difference in incidences between the MTX-exposed and MTX-unexposed patients in the time period. CONCLUSIONS: Our results suggest a small but significant increase in risk for CMM in patients treated with MTX. However, the risk increase observed was considerably lower than in earlier observations.