Dermoscopy is useful in improving the diagnosis of lymphangioma circumscriptum with characteristic structures and patterns and could assist in elucidating the presence of blood in lymphatic channels.

Serious adverse events are more common in elderly patients, although they may be related to other variants that are associated with this age group and not due to the treatment itself. Use of biologics was associated with lower risk of adverse events in the whole group. We found no differences in this association between young and elderly. These results are reassuring, although uncontrolled confounding could not be excluded as an explanation for these findings, and the power of the study to detect differences was low.

Apocrine hidrocystomas, above all in its pigmented variant, may represent a dermoscopic pitfall, being difficult to differentiate clinically and dermoscopically from basal cell carcinomas.

Background A variety of cutaneous smooth muscle neoplasms may arise in the skin and are frequently unrecognized by clinicians. There is sparse data relating to the dermoscopy of piloleiomyomas (PL), and nothing has been published about the dermoscopy of angioleiomyomas (AL) and leiomyosarcomas (LS). Objectives To evaluate the morphological findings of a large series of cutaneous PL, AL and LS under dermoscopic observation, comparing these findings among them.Methods Digital dermoscopic images of 136 histopathologically confirmed cases of cutaneous smooth muscle neoplasms (114 PL, 13 AL and 9 LS) collected from 10 Hospitals in Spain, Austria and Italy were evaluated for the presence of dermoscopic structures and patterns. ResultsThe pattern composed of a symmetric, total delicate pigment network with the variable presence of multiple hypopigmented areas in a painful lesion is the most common dermoscopic pattern associated with PL. This pattern was found in 69.3% of PL and in no cases of AL and LS. The most common and characteristic pattern associated with AL was the one composed of symmetric pink-reddish tumour with vessels, white structures and the absence of ulceration, which was found in 46.2% of AL, but also in 3.5% of PL, and in 22.2% of LS. Finally, the most common pattern associated with LS was the one composed of an asymmetric, multilobulated tumour with linear-irregular or polymorphic-atypical vessels and white structures, which was found in 44.4% of cases, but also in 0.9% of PL and in 15.4% of AL.Conclusion Dermoscopy is helpful in improving the diagnostic accuracy of PL. The dermoscopic patterns associated with AL and LS were more variable and less specific.

Background Glomus tumours (GTs) are benign cutaneous neoplasms derived from the neuromyoarterial apparatus with a strong predilection for acral sites, especially the subungual space. Current data regarding dermoscopy of these lesions are very limited. Objectives To analyse the dermoscopic structures and patterns seen in a large series of subungual (SUGTs) and extraungual glomus tumours (EUGTs) and to determine their diagnostic significance. Methods Clinical and dermoscopic images of 86 histopathologically proven cases of GTs (47 SUGTs and 39 EUGTs) collected from 9 hospitals in Spain, France, Italy, and Brazil were evaluated for the presence of dermoscopic structures and patterns. Similarly, 189 and 185 dermoscopic images of other ungual tumours and other extraungual non‐pigmented tumours, respectively, were evaluated for the same structures and patterns. Finally, we evaluate diagnostic testing accuracy calculating sensitivity (S), specificity (Sp), and positive and negative predictive values of the different patterns for the diagnosis of GT. Results Regarding SUGTs, four patterns were built from the combination of different structures. The pattern composed of a structureless purplish/red subungual spot with or without vessels reached the highest S (S1, 78.8%). The combination of a structureless purplish/red subungual spot and longitudinal erythronychia (LE) (S2) is highly specific (96.3%). Patterns S3 (proximal purplish/red subungual spot, LE, and distal notch) and S4 (bed subungual spot and onycholysis) are the most specific and exclusive of matrix and bed tumours, respectively. The most consistent pattern in EUGTs is composed of a structureless purplish‐white to reddish‐white homogeneous area and linear unfocused vessels (E) (S: 61.5%, Sp: 95.7%). EUGTs did not show lacunae, unlike other vascular tumours. Conclusions Dermoscopy is helpful in improving the diagnostic accuracy of GTs, not only in SUGTs but also when these lesions arise out of the ungual apparatus.

Dermoscopy is helpful in improving the diagnosis of arteriovenous tumours and allows the observer to differentiate them from other cutaneous lesions such as other vascular tumours, basal cell carcinomas and melanomas.

Background: Nodular hidradenoma is an uncommon, benign, adnexal neoplasm of apocrine origin which is a clinical simulator of other tumours. Objective: The aim of this study was to evaluate the morphological findings of a large series of nodular hidradenomas under dermoscopic observation. Methods: Dermoscopic examination of 28 cases of nodular hidradenomas was performed to evaluate specific dermoscopic criteria and patterns. Results: The most frequently occurring dermoscopic features were: (1) in 96.4% of cases, a homogeneous area that covered the lesion partially or totally, the colour of which was pinkish in 46.4% of cases, bluish in 28.6%, red-blue in 14.3%, and brownish in 10.7%; (2) white structures were found in 89.3% of cases; (3) in 82.1% of cases, vascular structures were also observed, especially arborising telangiectasias (39.3%) and polymorphous atypical vessels (28.6%). Conclusion: Nodular hidradenomas represent a dermoscopic pitfall, being difficult to differentiate clinically and dermoscopically from basal cell carcinomas and melanomas.

<b><i>Background:</i></b> Preoperative diagnosis of malignant collision tumors (MCT) is extremely difficult. The value of dermoscopy to improve the correct detection of these tumors has not been previously studied. This study aims to evaluate the diagnostic accuracy of MCT with and without dermoscopy and to describe the dermoscopic features of a large series of MCT. <b><i>Methods:</i></b> Dermoscopic images of 161 MCT were evaluated. Clinical and dermoscopic images of histopathologically proven MCT intermingled with other tumors were randomly presented to clinicians with different levels of experience, blinded to the diagnosis and objective of the study. The clinical and dermoscopic diagnostic accuracies were measured separately. <b><i>Results:</i></b> A total of 161 histopathologically proven cases of MCT were collected. The most frequent MCT was basal cell carcinoma-seborrheic keratosis collision tumor (CT; 37.9%), followed by basal cell carcinoma-melanocytic nevus CT (19.9%), and melanoma-seborrheic keratosis CT (6.8%). Diagnostic accuracy among experts on dermoscopy was 71.4%. The study included 119 participants. The percentage of correct diagnoses was 8% by naked eye examination and 36.4% by dermoscopy (<i>p</i> &#x3c; 0.001). The presence of the malignant component in the cases of MCT was not recognizable in 19.1% of cases by naked eye examination and in 11.8% of cases by dermoscopy (<i>p</i> &#x3c; 0.001). <b><i>Conclusions:</i></b> The diagnosis of MCT can be assisted and clarified by dermoscopy. However, many of these lesions manifest complex morphologies and continue to be challenging, even for experts on dermoscopy. Atypical, uncertain, or non-classifiable lesions still need a complete excision for the final diagnosis.