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A 39-year-old Hispanic woman is referred for evaluation of a lesion affecting the lateral edge of her left axilla. The patient noted the lesion several months ago, at which time it was the size of a pea. The lesion is asymptomatic, however, the patient reports feeling pressure when she is wearing tight clothing. She denies a history of systemic disease. Physical examination reveals a 2-cm firm nodule that is dusky red. Palpation of the area elicits tenderness. No similar lesions are noted elsewhere on the body.
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Biopsy of the lesion revealed an encapsulated, well-circumscribed dermal lesion composed of bland cells with spindled and oval nuclei interspersed within a mucinous stroma containing fibrillar collagen. Schwannomas, also referred to as neurilemmomas, are benign tumors that originate from Schwann cells of the neural sheath. Various histologic subtypes have been defined including microcystic/reticular, epithelioid, cellular, psammomatous, melanotic, and ancient. The later subtype is characterized by increased cellularity and atypia.1
Schwannoma neoplasms are usually firm in consistency, well-circumscribed, and asymptomatic although larger lesions may be accompanied by pain and numbness. Vestibular schwannomas may induce tinnitus and hearing loss. The neoplasm affects men and women equally and is most commonly diagnosed in middle-aged adults.2 The majority of schwannomas occur on the head and neck although case reports document occurrence within bronchi, feet, and tongue.3-5 Malignant transformation of schwannoma is exceedingly rare.6 Multiple schwannomas may accompany various genodermatoses such as neurofibromatosis type 2 and Carney complex.7
Stephen Schleicher, MD, is director of the DermDox Dermatology Centers, associate professor of medicine at Geisinger Commonwealth Medical College, and clinical instructor of dermatology at Arcadia University and Kings College.
References
1. Parvathidevi GK, Panduranga C, Munishwar GB. “Ancient” schwannoma of hypopharynx: a case report with review of literature. Indian J Otolaryngol Head Neck Surg. 2011;63(1):60-61. doi:10.1007/s12070-010-0068-7.
2. Iwashita T, Enjoji M. Plexiform neurilemmoma: a clinicopathological and immunohistochemical analysis of 23 tumours from 20 patients. Virchows Arch A Pathol Anat Histopathol. 1987;411(4):305-309. doi:10.1007/BF00713373
3. Aoyama Y, Miyamoto A, Fujii T, Fujimori S, Tamaoka M, Takai D. Primary bronchial schwannoma: a case report. Medicine (Baltimore). 2022;101(40):e31062. doi: 10.1097/MD.0000000000031062
4. Angelini A, Bevoni R, Biz C, Cerchiaro MC, Girolami M, Ruggieri P. Schwannoma of the foot: report of four cases and literature review. Acta Biomed. 2019;90(1-S):214-220. doi:10.23750/abm.v90i1-S.8079
5. Ulkü CH, Demir H, Yeşildemir HS, Esen H. Lingual schwannom [Lingual schwannoma]. Kulak Burun Bogaz Ihtis Derg. 2014;24(2):97-99. doi:10.5606/kbbihtisas.2014.79346
6. Oishi H, Ishii K, Bandou K, Ashida H, Abe M. Malignant schwannoma metastasizing to the parenchyma of the brain — case report. Neurol Med Chir (Tokyo). 2000;40(2):116-119. doi:10.2176/nmc.40.116
7. Genetic and Rare Disease Information Center. Schwannoma. National Center for Advancing Translational Science website. Accessed January 17, 2023. https://rarediseases.info.nih.gov/diseases/4767/schwannoma
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