{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,11]],"date-time":"2026-03-11T10:02:09Z","timestamp":1773223329292,"version":"3.50.1"},"reference-count":18,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,3,10]],"date-time":"2026-03-10T00:00:00Z","timestamp":1773100800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Current Oncology"],"abstract":"<jats:p>Primary intracranial squamous cell carcinoma (SCC) arising from an epidermoid cyst is an exceptionally rare and aggressive malignancy with a dismal prognosis. Conventional management typically involves gross total resection followed by wide-field radiotherapy; however, this intensive approach is often unfeasible for elderly or frail patients. We present a case of primary intracranial SCC in a 75-year-old woman who presented with rapid cochleovestibular deterioration. Imaging revealed subtle enlargement of a long-standing cerebellopontine angle epidermoid cyst. Subtotal resection was performed to preserve critical neurovascular structures adherent to the infiltrative tumor. Given the patient\u2019s poor performance status and the risk of toxicity from broad-field radiation, adjuvant Gamma Knife radiosurgery (GKS) was selected as a focal salvage modality. Despite the limited surgical margin, the patient has maintained a progression-free status with no radiographic evidence of disease progression for 18 months without neurological decline. This case highlights the diagnostic challenge of malignant transformation disguised by radiologic mimicry and demonstrates that GKS can serve as an effective and tolerable adjuvant strategy. We propose that for high-risk patients precluded from intensive multimodal therapy, focused stereotactic irradiation offers a viable alternative to secure local control while preserving quality of life and systemic immune integrity.<\/jats:p>","DOI":"10.3390\/curroncol33030158","type":"journal-article","created":{"date-parts":[[2026,3,10]],"date-time":"2026-03-10T12:39:08Z","timestamp":1773146348000},"page":"158","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Primary Intracranial Squamous Cell Carcinoma Arising from an Epidermoid Cyst: Successful Management with Subtotal Resection and Gamma Knife Radiosurgery in an Elderly Patient"],"prefix":"10.3390","volume":"33","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9611-4341","authenticated-orcid":false,"given":"Won Gun","family":"Kwack","sequence":"first","affiliation":[{"name":"Department of Pulmonary, Allergy, and Critical Care Medicine, College of Medicine, Kyung Hee University Hospital, 23 Kyung Hee Dae-ro, Dongdaemun-gu, Seoul 02447, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hong Jun","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Medical Oncology, College of Medicine, Kyung Hee University Hospital, 23 Kyung Hee Dae-ro, Dongdaemun-gu, Seoul 02447, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1007\/s11060-004-5175-4","article-title":"Malignant transformation of intra-cranial epithelial cysts: Systematic article review","volume":"74","author":"Hamlat","year":"2005","journal-title":"J. Neuro-Oncol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"e52","DOI":"10.1016\/j.wneu.2023.05.039","article-title":"Malignant transformation of an intracranial epidermoid cyst 25 years after initial surgery: A case report and systematic review","volume":"177","author":"Eatz","year":"2023","journal-title":"World Neurosurg."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Zuo, P., Sun, T., Wang, Y., Geng, Y., Zhang, P., Wu, Z., Zhang, J., and Zhang, L. (2021). Primary squamous cell carcinomas arising in intracranial epidermoid cysts: A series of nine cases and systematic review. Front. Oncol., 11.","DOI":"10.3389\/fonc.2021.750899"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1158","DOI":"10.1016\/j.jocn.2011.02.008","article-title":"Clinical characteristics and diagnostic imaging of epidermoid tumors","volume":"18","author":"Nagasawa","year":"2011","journal-title":"J. Clin. 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Neurosci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"e9423","DOI":"10.1097\/MD.0000000000009423","article-title":"Intracranial squamous cell carcinoma arising in a cerebellopontine angle epidermoid cyst: A case report and literature review","volume":"96","author":"Roh","year":"2017","journal-title":"Medicine"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Soffietti, R., Pellerino, A., Bruno, F., Mauro, A., and Rud\u00e0, R. (2023). Neurotoxicity from old and new radiation treatments for brain tumors. Int. J. Mol. Sci., 24.","DOI":"10.3390\/ijms241310669"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Goulet, M., Masucci, G.L., Taussky, D., and Levivier, M. (2025). History and Development of Clinical Use of Functional Stereotaxy for Radiation Oncologists: From Its Origins to Its Current State. Curr. 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