Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2023;13(2):e2023069 1 Dermoscopic Features of Schwannoma Dong Hyo Kim1, Je-Ho Mun1 1 Department of Dermatology, Seoul National University College of Medicine, Seoul, Korea Key words: dermoscopy, dermatoscopy, diagnosis, schwannoma, skin neoplasms Citation: Kim DH, Mun JH. Dermoscopic Features of Schwannoma. Dermatol Pract Concept. 2023;13(2):e2023069. DOI: https://doi. org/10.5826/dpc.1302a69 Accepted: July 11, 2022; Published: April 2023 Copyright: ©2023 Kim 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: Je-Ho Mun, MD, PhD, Department of Dermatology, Seoul National University College of Medicine, 101, Daehak-ro, Jongno-gu, Seoul 03080, Korea. Telephone: +82-2-2072-3274, Fax: +82-2-742-7344, E-mail: jehomun@gmail.com Introduction Schwannomas present as ill-defined soft tissue masses that are painful in one-third of cases [1]. Clinical diagnosis based on morphologic patterns alone is often difficult. It requires differentiation from other dermal or subcutaneous tumors, including neurofibroma, intradermal nevus, epidermal cyst, lipoma, and basal cell carcinoma [2]. Dermoscopy is a useful non-invasive diagnostic tool in differentiating various benign and malignant skin tumors. However, the dermoscopic fea- tures of schwannomas remain largely unknown. Case Presentation Cases of histopathologically confirmed schwannoma with available clinical and dermoscopic photographs from the Department of Dermatology, Seoul National University Hospital from 2016 to 2021 were analyzed. A total of 4 pa- tients (2 males, median age 38.5 [range 30-47] years) were included. All patients presented with palpable dermal or subcutaneous nodules. Fifty percent were accompanied with pain or tenderness. Two were located on the head and neck, and 2 were located on the upper limb. The primary clinical diagnoses of the patients included ganglion cyst, epidermal cyst, and lipoma. In all 4 patients, tumors were surgically removed. Histopathological examination revealed encapsu- lated spindle cell tumor with characteristic hypercellular and hypocellular areas, which is consistent with schwannoma. Polarized dermoscopy in half of the cases revealed a dermo- scopic pattern of arborizing vessels with whitish translucent surfaces (Table 1 and Figure 1). Written informed consent for publication of clinical details and clinical images was ob- tained from the patients. Conclusions As schwannomas are usually located in the dermis and sub- cutaneous layer, dermoscopic findings may not be prominent. Nevertheless, in our case series, schwannomas demonstrated arborizing vessels and translucent surfaces on dermoscopy in half of the cases. Dermoscopic features of schwannoma have been reported previously in the literature [1,3]. One case report described multiple arborizing vessels and speck- led pigmentation on a translucent yellowish surface [1]. These findings are similar to our cases. Therefore, we sug- gest that dermoscopy may help differentiate schwannoma 2 Research Letter | Dermatol Pract Concept. 2023;13(2):e2023069 from other dermal or subcutaneous tumors in select cases by narrowing down the differential diagnosis. Dermoscopic patterns of neurofibromas include peripheral pigmented networks and pink-red structureless areas [4]. Epidermal cysts present a distinctive central punctum [5]. Dermoscopic patterns of intradermal nevus include pigmented structures such as dots, globules, and comma-like vessels [6]. Although basal cell carcinoma presents arborizing vessels, additional features include blue-gray ovoid nests, leaf-like structures, ulceration, multiple small erosions, and spoke-wheel pig- mentations [6]. The limitations of our study include its small sample size. In addition, as we excised the tumors with linear in- cision and extirpation methods, we could not investigate Table 1. Clinical and dermoscopic findings of four patients with schwannoma. No Sex Age at first visit Duration of disease Location Clinical features Symptoms Primary diagnosis Dermoscopic features Size of excised tissue (cm) 1 M 30 6 months Dorsum of right 1st finger 0.5 cm sized palpable dermal or subcutaneous nodule (-) Ganglion cyst Whitish translucent surface with arborizing vessels 0.8 x 0.6 x 0.4 2 M 32 18 months Right shoulder Dermal or subcutaneous nodule Tenderness Epidermal cyst, lipoma Whitish translucent surface with arborizing vessels 1.6 x 1.3 x 0.9 3 F 45 Unknown Left anterior neck Palpable dermal or subcutaneous nodule (-) Epidermal cyst None 0.5 x 0.5 x 0.4 4 F 47 35 years Left occipital scalp 3cm sized dermal or subcutaneous nodule Pain Lipoma, epidermal cyst None 7.0 x 3.0 x 1.3 M = male; F = female. Figure 1. Clinical photographs (A,E). Dermoscopic image showing a whitish translucent structure with arborizing vessels (B,F). Photographs of surgically excised tumors (C,G). A histopathologic study revealed an encapsulated spindle cell tumor with a characteristic hypercellular Antoni A area and hypocellular Antoni B area. (D,H; H&E; original magnifications: x100). Research Letter | Dermatol Pract Concept. 2023;13(2):e2023069 3 the association between the location or depth of the tumors and the presence of dermoscopic findings in schwannomas. Further studies are warranted to elucidate the dermoscopic patterns of schwannomas. References 1. Daulatabad D, Pandhi D, Tanveer N, Sharma S, Kaur I. Solitary dome-shaped erythematous lump of long duration on the palm. Indian J Dermatol Venereol Leprol. 2018;84(4):437-439. DOI: 10.4103/ijdvl.IJDVL_845_16. PMID: 29380752. 2. Park JS, Moon J, Cho SI, Mun JH. Schwannoma presenting as a scalp mass: A case report with magnetic resonance imaging find- ings. Ann Dermatol. 2020;32(1):64-68. DOI: 10.5021/ad.2020 .32.1.64. PMID: 33911711. PMCID: PMC7992636. 3. Miyamoto K, Yanagi T, Maeda T, et al. Dermoscopic features of haemorrhagic schwannoma. Australas J Dermatol. 2021;62(2) :e322-e323. DOI: 10.1111/ajd.13477. PMID: 33094832. 4. Duman N, Elmas M. Dermoscopy of cutaneous neurofibromas associated with neurofibromatosis type 1. J Am Acad Dermatol. 2015;73(3):529-531. DOI: 10.1016/j.jaad.2015.05.021. PMID: 26282805. 5. Suh KS, Kang DY, Park JB, et al. Usefulness of dermoscopy in the differential diagnosis of ruptured and unruptured epider- mal cysts. Ann Dermatol. 2017;29(1):33-38. DOI: 10.5021 /ad.2017.29.1.33. PMID: 28223744. PMCID: PMC5318524. 6. Williams NM, Navarrete-Dechent C, Marghoob AA, Abarzua-Araya Á, Salerni G, Jaimes N. Differentiating basal cell carcinoma from intradermal nevi along the eyelid margin with der- moscopy: A case series. J Am Acad Dermatol. 2021;84(1):173-175. DOI: 10.1016/j.jaad.2020.04.059. PMID: 32330634. PMCID: PMC8442835.