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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. Results: The 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. [ABSTRACT FROM AUTHOR]

Background: No specific features of nevus-associated melanoma (NAM) are currently defined., Objective: To identify clinical/dermoscopic features of NAM., Methods: Retrospective evaluation of histopathologically diagnosed NAM., Results: Eighty of 165 NAMs had a clinically recognizable nevus component, often raised or nodular, most frequently characterized by different morphologic clones and/or colors. In 111 of 165 NAMs, dermoscopy showed a nevus component, prevalently characterized by regular dots/clods and structureless brown areas. Clinically, the melanoma component was eccentric/peripheral in 45 of 80 cases and central in 35 of 80; dermoscopically, the figures were 59 of 111 and 52 of 111, respectively. Melanomas associated with congenital nevi (C-NAMs) occur at a younger age and have a thicker Breslow depth than melanomas associated with acquired nevi (NC-NAMs). Dermoscopically, regular dots/globules characterize C-NAMs, and hypopigmented structureless areas characterize NC-NAMs., Limitations: Retrospective analysis., Conclusion: C-NAMs are more often central to a congenital nevus, with a clod/globular or structureless brown pattern, typical of young patients. NC-NAMs are frequently hypopigmented nodules/plaques, eccentric/peripheral, with hypopigmented structureless areas, typical of older patients., (Copyright © 2020 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

The specific anatomy of the glabrous skin, characterized by marked orthokeratosis and the presence of furrows and ridges, results in peculiar dermoscopic patterns of acral melanocytic lesions. Most frequently, acral nevi are typified by a parallel furrow pattern and acral melanoma (AM) by a parallel ridge pattern (PRP). Although the dermoscopic patterns of AM have been extensively investigated, little attention has been paid to site-related differences between palmar and plantar AM. The current study aimed to compare patients' characteristics, melanoma thickness, and the morphologic variability of AM depending on the localization on palms or soles. Patients demographics and dermoscopic images of 118 AM, including 99 (83.9%) plantar and 19 (16.1%) palmar lesions (mean thickness, 2.1 mm), were extracted from the databases of seven pigmented skin lesion clinics and were evaluated for the presence of predefined criteria. Palmar melanomas were remarkably more frequent in women (male-to-female ratio, 1/3.8) and thinner than plantar melanomas (1.3 vs. 2.2 mm). Dermoscopically, no significant differences were found between plantar and palmar melanomas, with PRP scored in 64.6 and 68.4% of plantar and palmar lesions, respectively. Non-site-specific melanoma criteria were detected in 83.9% of lesions and, among melanomas not exhibiting a PRP, 95.1% showed at least one non-site-specific melanoma criterion. In conclusion, plantar and palmar AMs show sex-related and thickness-related differences, but do not differ with respect to their dermoscopic features. For cases lacking the PRP, non-site-specific melanoma criteria may be considered as helpful additional clues for the correct diagnosis.

Objective: The objective was to describe the clinical and dermoscopic characteristics of difficult-to-diagnose melanomas (DDM)., Design: This study was a retrospective analysis of clinical data and dermoscopic images in a series of excised melanomas., Setting: Cases were obtained from the database registers of three public hospitals in Barcelona (Spain), Naples (Italy), and Graz (Austria)., Patients: A total of 97 tumors with a main preoperative diagnosis different from melanoma and without sufficient criteria to be diagnosed clinically and dermoscopically as melanoma were studied. We studied clinical data from the patients and lesions, mean reason for excision, and consensus dermoscopic description of the lesions according to pattern analysis performed by a panel of four dermoscopists to obtain clues that allow these melanomas to be recognized., Results: Ninety-three DDMs were evaluated. Three main dermoscopic categories of DDM have been identified: (1) DDMs lacking specific features (16/97), (2) DDMs simulating nonmelanocytic lesions (14/93), and (3) DDMs simulating benign melanocytic proliferations (67/93). The reasons for excision were (1) the subjective history of change referred by the patient (38% of cases), (2) the presence of clinical and/or dermoscopic "hints" for biopsy (33% of cases), and (3) the objective evidence of changes detected by digital dermoscopic follow-up (29% of cases)., Conclusions: A diagnostic algorithm is proposed not to miss melanoma.