SKIN November 2019 Volume 3 Issue 6 Copyright 2019 The National Society for Cutaneous Medicine 459 SHORT COMMUNICATIONS Schwannoma of the Scalp Mimicking a Pilar Cyst Peter W. Hashim, MD, MHS1, Stephanie Liu, DO, MBA1, Garrett T. Desman, MD1, Cerrene N. Giordano, MD1 1Department of Dermatology, Icahn School of Medicine at Mount Sinai, New York, NY Schwannomas are benign nerve sheath tumors comprised of myelin-producing Schwann cells. Head and neck schwannomas constitute roughly 25% of cases, but lesions of the scalp are uncommon. (1-3) Here, we describe a schwannoma of the scalp that clinically presented as a pilar cyst. A 17-year-old male presented with a five- year history of a subcutaneous nodule located on his occipital scalp. The patient noted slight growth of the lesion over the past six months and complained of intermittent tenderness. He denied any discharge from the area. He was interested in surgical removal due to the clinical symptoms. His medical history included nodulocystic acne. Physical examination revealed a 2.3 cm x 2.3 cm firm, mobile, subcutaneous nodule of the midline occipital scalp (Figure 1). No central punctum was noted. A pilar cyst was suspected. The lesion was excised under local anesthesia and was removed, without difficulty, as a solitary, encapsulated mass. Histologic examination revealed a circumscribed dermal proliferation of spindle cells with nuclei arranged in parallel rows and separated by an eosinophilic fibrillar material (Figure 2). The neoplasm was surrounded by a well-defined capsule partially composed of a compressed peripheral nerve. Figure 1. Midline occipital scalp with the outlined border of the schwannoma. INTRODUCTION CASE REPORT SKIN November 2019 Volume 3 Issue 6 Copyright 2019 The National Society for Cutaneous Medicine 460 Figure 2. Histological section (H&E, 20x) showing a dermal spindle cell proliferation. Schwannomas most often appear between the 3rd and 5th decade and show equal prevalence between males and females. (2) Over 90% arise sporadically as solitary lesions, with a natural history of slow growth and an absence of symptoms. (4). Schwannomas of the head and neck region most often occur intracranially, including the bilateral “acoustic neuromas” diagnostic of type 2 neurofibromatosis. Schwannomas are generally considered benign neoplasms, although malignant lesions have been reported, including on the scalp. (5) In our case, the patient’s lesion was largely asymptomatic, only becoming tender after several years of slow growth. Excision was straightforward given the well-encapsulated nature of the tumor. This case adds to the small number of reported schwannomas occurring in the superficial tissues of the scalp, an uncommon location even amongst head and neck schwannomas. (6) The differential diagnosis of a firm, mobile, subcutaneous nodule of the scalp typically includes pilar cyst as well as the less common dermoid cyst, pilomatricoma, and lipoma. Schwannomas are not typically suspected, as lesions of the scalp are rarely reported. (1, 3) This report highlights that a solitary scalp schwannoma can be included as an unlikely possibility. Surgery for more symptomatic lesions remains the treatment of choice. Conflict of Interest Disclosures: None Funding: None Corresponding Author: Cerrene N. Giordano, MD Department of Dermatology, Icahn School of Medicine at Mount Sinai 325 West 15th Street New York, NY 10011 Tel: (212) 367-0145 Email: Cerrene.giordano@gmail.com References: 1. Asuquo ME, Nwagbara VI, Akpan SO, Otobo FO, Umeh J, Ebughe G, et al. Recurrent benign schwannoma of the scalp: Case report. Int J Surg Case Rep. 2013;4(1):65-7. 2. Langner E, Del Negro A, Akashi HK, Araujo PP, Tincani AJ, Martins AS. Schwannomas in the head and neck: retrospective analysis of 21 patients and review of the literature. Sao Paulo Med J. 2007;125(4):220-2. 3. Mohan K, Manjunath H. Cutaneous schwannoma masquerading as trichilemmal cyst over scalp in a young male. Indian J Dermatol. 2013;58(5):407. 4. Beaman FD, Kransdorf MJ, Menke DM. Schwannoma: radiologic-pathologic correlation. Radiographics. 2004;24(5):1477-81. 5. Demir Y, Tokyol C. Superficial malignant schwannoma of the scalp. Dermatol Surg. 2003;29(8):879-81. 6. Leu YS, Chang KC. Extracranial head and neck schwannomas: a review of 8 years experience. Acta Otolaryngol. 2002;122(4):435-7. DISCUSSION mailto:Cerrene.giordano@gmail.com