Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2024;14(2):e2024143 1 Dermoscopy of Thick Scalp Melanoma: Is It Always an Easy Diagnosis? Sebastiano Pellerone1, Chiara Pensa2, Giustino Riccio1, Gabriella Brancaccio1, Giuseppe Argenziano1, Elvira Moscarella1 1 Dermatology Unit, University of Campania Vanvitelli, Naples, Italy 2 Dermatology Unit, Tor Vergata University, Rome, Italy Key words: Scalp melanoma, thick melanoma, Dermoscopy Citation: Pellerone S, Pensa C, Riccio G, Brancaccio G, Argenziano G, Moscarella E. Dermoscopy of Thick Scalp Melanoma: Is It Always an Easy Diagnosis? Dermatol Pract Concept. 2024;14(2):e2024143. DOI: https://doi.org/10.5826/dpc.1402a143 Accepted: February 8, 2024; Published: April 2024 Copyright: ©2024 Pellerone et al. This is an open-access article distributed under the terms of the Creative Commons Attribution- NonCommercial License (BY-NC-4.0), https://creativecommons.org/licenses/by-nc/4.0/, which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original authors and source are credited. Funding: None. Competing Interests: None. Authorship: All authors have contributed significantly to this publication. Corresponding Author: Sebastiano Pellerone, Dermatology Clinic,Via Sergio Pansini n5, 84081, Napoli, Italy. Telephone: 0039 3519636607, Email: pseba90@gmail.com Introduction Scalp melanoma (SM) tends to present a greater invasiveness at diagnosis and a worst prognosis compared to cutaneous melanomas at other body sites [1]. Previous studies have in- vestigated the dermoscopic features of SM, mainly focusing on thin melanomas [2,3]. Little is known about dermoscopic features of thick (>0.8 mm Breslow) melanoma of the scalp [4,5,6]. Case Presentation This was a retrospective case control study conducted at the Dermatology Unit of the University of Campania Vanvi- telli, Naples, Italy. We identified 30 cases of scalp melanoma with a Breslow thickness equal to or greater than 0.8 mm and compared them to a control group of 63 dorsal mela- nomas matched for thickness, age, and ulceration. Clinical characteristics of the patients were gathered and tabulated, dermoscopy images were analyzed by three observers in consensus (EM, SP, CP). Statistical analysis was performed using the R statistical software, version 4.0. Continuous and categorical data are presented as means and frequencies and were compared using T-student test and Pearson’s Chi- squared test or the Fisher’ Exact test, when appropriate. The Type I error probability associated with all tests in this study was set to 0.05. Clinical and dermoscopic features are summarized in Table S1. The great majority of patients with SM were men (90%, p-value 0,01). SM presented dermoscopic features related to lentigo maligna subtype in a significantly higher percentage than melanoma on the back. (Table S1). Examining the over- all pattern of lesions, we categorized scalp melanoma cases into six main groups. Lentigo maligna melanoma group (n 12, 40%) displaying dermoscopic features typical of len- tigo maligna melanoma, such as pseudonetwork and obliter- ation of hair follicles. Blue-Black positive cases (n 12, 40%) positive to the blue black rule. Basal cell carcinoma-like 2 Research Letter | Dermatol Pract Concept. 2024;14(2):e2024143 cases (n 2, 6,7%) showing arborizing vessels and ulceration. Angioma-like lesions (n 2, 6,7%) showing vascular lacunae. Two cases displayed typical features for squamous cell carcinoma and seborrheic keratosis, namely white structureless areas and a whitish collar of the lesion and, light brown fingerprint-like parallel structures respectively (Figure 1 and 2). Only few studies have focused on dermoscopic charac- teristics of scalp melanoma. In the study by Stanganelli et al. [3] authors concluded that thin SM tends to display network Figure 1. (A, D) Invasive melanoma in a 75 year-old man. The flat brown macule was arising in hair bearing scalp (A). In dermoscopy atypical pseudo-network and regression are detected. (B, E) Invasive melanoma on the parietal region in a 63-year-old man with androgenic alopecia, 2 mm Breslow thickness. Clinically, the lesion appears as a black, eroded nodule and satellitosis is already visible (B). In dermoscopy the lesion is positive for the blue-black rule (E). (C; F) Invasive melanoma on the scalp of a 66-year-old woman, 39 mm Breslow thickness, pT4b.Clinically, the lesion appears nodular and exophytic (C). In dermoscopy milky red areas and large arborising vessels are found on a white background (F). Figure 2. (A, C) Invasive melanoma on the parietal region in a 70-year-old man with androgenic alopecia, Breslow thickness 3 mm. Clinically, it mimics an extended angioma (A). In dermoscopy, white streaks are found all over the lesion (C). (B, D) Invasive melanoma on the frontal region in a 75-year-old man with androgenic alopecia, superficial spreading melanoma 3.3 mm Breslow thickness. Clinically, the lesion ap- pears partially nodular with ill defined borders (B). In dermoscopy a unspecific pattern is detected with brownish pigmentation, white lines and milky red areas (D). Research Letter | Dermatol Pract Concept. 2024;14(2):e2024143 3 References 1. Porto AC, Pinto Blumetti T, Oliveira Santos Filho IDA, et al. Primary cutaneous melanoma of the scalp: Patterns of clinical, histological and epidemiological characteristics in Brazil. PLoS One. 2020 Oct 23;15(10):e0240864. doi: 10.1371/journal.pone .0240864. PMID: 33095773; PMCID: PMC7584174. 2. Spyridis I, Papageorgiou C, Apalla Z, et al. The peculiar derma- toscopic pattern of scalp melanoma. J Eur Acad Dermatol Vene- reol. 2022 Sep;36(9):1564-1567. doi: 10.1111/jdv.18145. Epub 2022 Apr 22. PMID: 35426175. 3. Stanganelli I, Argenziano G, Sera F, et al. Dermoscopy of scalp tumours: a multi-centre study conducted by the international dermoscopy society. J Eur Acad Dermatol Venereol. 2012 Aug;26(8):953-63. doi: 10.1111/j.1468-3083.2011.04188.x. Epub 2011 Jul 26. PMID: 21790795. 4. Licata G, Scharf C, Ronchi A, et al. Diagnosis and Management of Melanoma of the Scalp: A Review of the Literature. Clin Cos- met Investig Dermatol. 2021 Oct 7;14:1435-1447. doi: 10.2147/ CCID.S293115. PMID: 34675579; PMCID: PMC8504470. 5. Porto, A.C., Pinto Blumetti, T., Calsavara, V.F. et al. A cross- sectional study of clinical, dermoscopic, histopathological, and molecular patterns of scalp melanoma in patients with or with- out androgenetic alopecia. Sci Rep 12, 15096 (2022). https://doi .org/10.1038/s41598-022-17108-z 6. Zalaudek I, Leinweber B, Soyer HP, Petrillo G, Brongo S, Argenziano G. Dermoscopic features of melanoma on the scalp. J Am Acad Dermatol. 2004 Aug;51(2 Suppl):S88-90. doi: 10.1016 /j.jaad.2003.12.024. PMID: 15280821. or pseudo network with regression as main features, thick scalp melanoma was categorized as unspecific in its dermo- scopic appearance. In our study we confirm the variegated demoscopic appearance of SM that can show features typ- ical for non melanoma skin cancer. Since NMSC are very often found on the scalp, making an accurate preoperative diagnosis is crucial because the tumors may need a differ- ent management approach. As expected, the main features differentiating thick SM from melanomas located on the back were those related to the lentigo maligna subtype of melanoma. Regarding the other dermoscopic features, micro ulceration, arborizing blood vessels and pink structureless areas were more frequent in SM, even if the data were not statistically significant. Conclusion Thick SM often exhibit characteristics typical of head and neck melanomas. Most of our cases demonstrated fea- tures resembling lentigo maligna melanoma (40%) or were positive for the blue-black rule (40%). A smaller num- ber of cases (20%) could be indistinguishable from non- melanocytic lesions such as basal cell carcinomas, squamous cell carcinomas, angiomas, or seborrheic keratoses, making clinical-dermoscopic diagnosis challenging.