J Korean Neurosurg Soc.  2012 Aug;52(2):148-151. 10.3340/jkns.2012.52.2.148.

Malignant Transformation of an Epidermoid Cyst in the Cerebellopontine Angle

• Chon KH
• Lee JM
• Koh EJ
• Choi HY

• KMID: 2190555
• DOI: http://doi.org/10.3340/jkns.2012.52.2.148

Abstract

Intracranial squamous cell carcinoma is extremely rare, with most of the cases arising from malignant transformation of an epidermoid or a dermoid cyst. The patient presented with facial weakness. Initial magnetic resonance imaging revealed a mass in the right cerebellopontine angle. A subtotal resection was performed via right retrosigmoid suboccipital approach. Histopathological findings were consistent with an epidermoid tumor. Five months later, the patient underwent gamma knife radiosurgery due to highly probable recurrent epidermoid tumor. Two years after, the patient's neurological deficit had been newly developed, and follow-up magnetic resonance imaging demonstrated a large contrast-enhancing tumor in the left cerebellopontine angle, which compressed the brainstem. After resection of the tumor, histopathological examinations revealed a squamous cell carcinoma probably arising from an underlying epidermoid cyst. We report a case of an epidermoid tumor in the cerebellopontine angle that transformed into a squamous cell carcinoma.

Keyword

Epidermoid cyst; Malignancy

MeSH Terms

Brain Stem
Carcinoma, Squamous Cell
Cerebellopontine Angle
Dermoid Cyst
Epidermal Cyst
Follow-Up Studies
Humans
Magnetic Resonance Imaging
Radiosurgery

Figure

• 

  Fig. 1 A : T2-weighted image shows a high signal mass in the right CPA. B : Contrast-enhanced T1-weighted image shows nonenhancing huge mass. C : Diffusion weighted image shows very high signal intensity mass in the right CPA suggestive of an epidermoid cyst. D : The cyst is lined by keratinizing squamous epithelium and filled with lamellated keratinous debris (Hematoxylin-Eosin stain, ×100). CPA : cerebellopontine angle.

• 

  Fig. 2 A : In July 2009, contrast-enhanced axial T1-weighted image shows strong enhancement of the small nodular lesion (black arrow) in the right cerebellar hemisphere. The patient received GKRS in this lesion. B : In January 2011, follow-up contrast-enhanced axial T1-weighted image shows that there is no enhanced tumor. GKRS : gamma knife radiosurgery.

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  Fig. 3 A : T2-weighted image shows isodense signal intensity mass in the left CPA. B : Contrast-enhanced axial T1-weighted image shows strong enhancement of the nodular lesion in the left CPA. C : Contrast-enhanced sagittal T1-weighted image shows strong enhancement. D : The specimen contains high cellular area with enlarged pleomorphic and hyperchromatic nuclei, which is a component of poorly differentiated squamous cell carcinoma (Hematoxylin-Eosin stain, ×200). CPA : cerebellopontine angle.

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