1Dermatology Service, Hospital Universitario Reina Sof ía, Instituto Maimónides de Investigación Biomédica, Córdoba, Spain; 2Department of Dermatology, Complejo Hospitalario de Granada, Granada, Spain *Corresponding Author’s e-mail: ismenios@hotmail.com ورم عصيب متحدد ومنعزل قرائن فحص اجللد لتسهيل التشخيص بابلو فريدينانز-كريهوت و ريكاردو رويز-فيال فريدي Solitary Circumscribed Neuroma Dermoscopic clues to facilitate diagnosis Pablo Fernández-Crehuet1 and *Ricardo Ruiz-Villaverde2 A 66-year-old woman presented to the Dermatology Outpatient Clinic of the Hosp-ital Universitario Reina Sof ía, Córdoba, Spain in 2017 with a 10-year history of a painful slow- growing erythematous lesion on her chin. A clinical examination revealed a pink, translucent, firm, non- ulcerated papule of 6 mm [Figure 1]. No similar cutan- eous or mucosal lesions were noted anywhere else on the body. Polarised non-contact dermoscopy of the papule (Dermlite DL3N®, 3Gen Inc., San Juan Capis- trano, California, USA) indicated arborising vessels on a pinkish-reddish background, a central white spot and peripheral pigmentation [Figure 2]. Following complete surgical excision of the lesion, a histopathological examination revealed a well-cir- cumscribed partially-encapsulated dermal prolifera- tion comprised of spindle cells with scanty pale cyto- plasm and elongated wavy nuclei. The nuclei were grouped in distinct fascicles set in fibrillar, collagenous and occasionally myxoid stroma [Figure 3]. The patient was subsequently diagnosed with a solitary circum- scribed neuroma (SCN). She recovered successfully following the surgery, with no recurrence observed after 10 months of follow-up. Comment Also known as palisaded encapsulated neuromas, SCNs usually present in adulthood as asymptomatic small nodules of between 2–6 mm, mainly located on the face. However, cases have been described in other locations, including the shoulder, hands, arms, feet and mucosal areas.1,2 Mucosal neuromas have been linked with multiple endocrine neoplasia 2b syndrome and phosphatase and tensin homolog deleted on chrom- osome 10 hamartoma tumour syndromes, including Cowden syndrome, Proteus syndrome and Bannayan- Riley-Ruvalcaba syndrome.3,4 Histologically, the exam- ination of an SCN reveals a well-circumscribed partially- encapsulated intradermal nodule comprised of spindle cells grouped in distinct fascicles with a lack of nuclear interesting medical image Sultan Qaboos University Med J, February 2018, Vol. 18, Iss. 1, pp. e116–117, Epub. 4 Apr 18 Submitted 4 Nov 17 Revision Req. 31 Dec 17; Revision Recd. 2 Jan 18 Accepted 11 Jan 18 Figure 1: Photograph of a pink, translucent, firm, dome-shaped papule on the left side of the chin of a 66-year-old woman. doi: 10.18295/squmj.2018.18.01.023 Pablo Fernández-Crehuet and Ricardo Ruiz-Villaverde Interesting Medical Image | e117 ovoid nests, globules, dots or blotches and brown- grey leaf-like small erosions or ‘wheel-spoke’ areas—is not sufficient to warrant avoiding excision of the lesion. Clinicians should be aware of the characteristic arborising vascular patterns of SCN which appear dermoscopically as white patches on a pink-white background.4,5 References 1. Reed RJ, Fine RM, Meltzer HD. Palisaded, encapsulated neuro- mas of the skin. Arch Dermatol 1972; 106:865–70. doi: 10.1001/ archderm.1972.01620150051016. 2. Magnusson B. Palisaded encapsulated neuroma (solitary circ- umscribed fibroma) of the oral mucosa. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996; 82:302–4. doi: 10.1016/ S1079-2104(96)80356-8. 3. Megahed M. Palisaded encapsulated neuroma (solitary circ- umscribed neuroma): A clinicopathologic and immunohist- ochemical study. Am J Dermatopathol 1994; 16:120–5. doi: 10.10 97/00000372-199404000-00002. 4. Fernández-Crehuet P, Fernández-Crehuet JL, Ruiz-Villaverde R, Sanz-Trelles A. Solitary circumscribed neuroma: A clinical and dermoscopic mimicker of basal cell carcinoma. Int J Dermatol 2015; 54:e275–7. doi: 10.1111/ijd.12828. 5. Moyano EG, Blanca MA, Pilar LM, Martos AO, Fernandez Ballesteros MD, Trelles AS. Homogeneous white patch in dermoscopy of solitary circumscribed neuroma. J Am Acad Dermatol 2017; 76:S84–5. doi: 10.1016/j.jaad.2015.11.020. pleomorphism and mitosis.4 Immunohistochemical studies of SCN cases have demonstrated positive cell staining for S100 proteins, collagen type IV and vimentin.2–4 In cases where the diagnosis is not clear, glial fibrillary acid protein and epithelial membrane antigen staining may also be necessary.3 From a physiopathological point of view, it has been suggested that SCNs are caused by the inexplic- able hamartomatous growth of Schwann cells over axons.4 The clinical and dermoscopical differential diagnosis should include basal cell carcinomas (BCCs), adnexal tumours, neurothekeomas, vascular tumours and intradermal melanocytic naevi.4 In addition, SCNs may have similar histological findings to those of neurofibromas and schwannomas; however, while neurofibromas lack a capsule and contain a muco- polysaccharide ground substance, schwannomas are generally subcutaneous and contain Antoni types A and B tissue patterns and Verocay bodies with no axons present.3 Immunostaining with human mela- noma black-45, melan-A, tyrosinase and cluster of differentiation (CD)34 can be useful to differentiate these entities. Dermoscopy is a useful noninvasive tool that helps to identify tumours that mimic BCCs.4 However, the absence of BCC features—including blue-grey Figure 2: Dermoscopic image showing a symmetrical non-pigmented lesion with an arborising vascular pattern and surrounded by a peripheral dark-yellowish halo. Figure 3: Haematoxylin and eosin stain at x10 magnif- ication showing a well-circumscribed dermal nodular tumour comprised of small spindle cells (asterisk) without atypia or mitotic evidence of malignancy. The cells are grouped in small fascicles separated by grooves embedded in an eosinophilic fibrillar matrix (arrow). https://doi.org/10.1001/archderm.1972.01620150051016 https://doi.org/10.1001/archderm.1972.01620150051016 https://doi.org/10.1016/S1079-2104%2896%2980356-8 https://doi.org/10.1016/S1079-2104%2896%2980356-8 https://doi.org/10.1097/00000372-199404000-00002 https://doi.org/10.1097/00000372-199404000-00002 https://doi.org/10.1111/ijd.12828 https://doi.org/10.1016/j.jaad.2015.11.020