Malignant squamous cell carcinoma arising in a previously resected cerebellopontine angle epidermoid
- Department of Neurosurgery, Women's and Children's Hospital, North Adelaide, Australia
- Department of Anatomical Pathology, SA Pathology, Adelaide, Australia
- Department of Neurosurgery, Royal Adelaide Hospital, Adelaide, Australia
Department of Neurosurgery, Royal Adelaide Hospital, Adelaide, Australia
DOI:10.4103/sni.sni_99_17Copyright: © 2017 Surgical Neurology International This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
How to cite this article: Annika Mascarenhas, Alyssa Parsons, Caroline Smith, Cindy Molloy, Alistair Jukes. Malignant squamous cell carcinoma arising in a previously resected cerebellopontine angle epidermoid. 10-Aug-2017;8:186
How to cite this URL: Annika Mascarenhas, Alyssa Parsons, Caroline Smith, Cindy Molloy, Alistair Jukes. Malignant squamous cell carcinoma arising in a previously resected cerebellopontine angle epidermoid. 10-Aug-2017;8:186. Available from: http://surgicalneurologyint.com/surgicalint-articles/malignant-squamous-cell-carcinoma-arising-in-a-previously-resected-cerebellopontine-angle-epidermoid/
Background:Malignant squamous cell differentiation of an epidermoid cyst can carry a significantly poor prognosis and very little is known about this entity.
Case Description:We present the case of a 35-year-old lady, with primary malignant squamous cell carcinoma (SCC) arising from a previously partially resected cerebellopontine angle epidermoid cyst almost 5 years after initial resection. We also review the relevant literature.
Conclusion:The imaging findings, histopathology, and management of a malignant SCC arising from a benign epidermoid cyst are discussed with recommendation for increased surveillance and follow-up, even for classically accepted benign lesions.
Keywords: Cerebellopontine angle tumour, Epidermoid, Squamous cell carcinoma, Malignant transformation
Epidermoid cysts are benign, slow growing, extra-axial tumors that account for ~1% of all intracranial tumors. Embryologically, they are derived from ectodermal inclusions during neural tube closure.[
The patient originally presented in 2010 with headaches. Neurological exam was unremarkable. Magnetic resonance imaging (MRI) demonstrated a CP angle lesion that was lobulated and predominantly of low signal intensity in the prepontine and right ambient cistern, with a few small foci of increased signal intensity on diffusion imaging, which was consistent with an epidermoid along with a small left-sided acoustic neuroma. At that time, a right retrosigmoid craniotomy was performed with the intention of decompressing the brainstem and cranial nerves. The right CP angle lesion was partially resected with a small residual left coating the anterior brainstem in the prepontine cistern. Histology demonstrated an epidermoid tumor with typical histological features of lamellar keratin and benign squamous epithelium. The small residual was monitored with serial MRI scans. Approximately 5 years later, routine follow-up MRI demonstrated marked growth of the residual lesion with development of a multilobulated enhancing cystic component. The patient complained of a 6-month history of right-sided facial numbness. After discussion with the patient, the decision was made to reoperate and resect this lesion. A repeat right retrosigmoid craniotomy was performed. Intraoperatively, the lesion was cystic with an anteromedial solid component adhering to the lateral aspect of the brainstem. There appeared to be a dural attachment which was resected. The patient awoke well initially, however, subsequently developed a House–Brackmann grade 5 facial palsy on day 2 [
(a) MRI T2 CIS axial demonstrating pre-pontine and ambient cistern lesion in 2010. (b) MRI T1 post gadolinium in 2010 demonstrating no significant enhancement. (c) MRI T1 post gadolinium in 2015 demonstrating no significant enhancement. (d) MRI T1 post gadolinium in 2016 demonstrating lobulated, enhancing mixed cystic/solid lesion
Histology demonstrated SCC with areas of poorly differentiated sarcomatoid elements. The squamous component comprised large epithelial cells with hyperchromatic, pleomorphic nuclei, and abundant, dense eosinophilic cytoplasm. Keratinization and intercellular bridges were present. There were no benign squamous cellular features. An acellular keratin pearl was present. The sarcomatoid component comprised highly atypical spindle cells displaying hyperchromatic, pleomorphic nuclei, and brisk mitotic activity. Areas of necrosis were also present. Immunohistochemistry was performed. The squamous cell component was positive for CK5/6, and had positive nuclear staining for P63. Some of the sarcomatoid spindle cells showed positive staining for cytokeratin markers AE1/3 and CK5/6 and P63. They were negative for CD34, S100, desmin, GFAP, CD31, and myogenin. The previous histology was reviewed which showed benign squamous cyst wall and keratin. There were no malignant features [
(a) first histology H and E staining demonstrating benign squamous cyst wall and keratin with no malignant features. (b) Second resection histology H and E staining showing metastatic squamous cell carcinoma features. (c) and (d) immunohistochemistry staining demonstrating malignant squamous cell markers of CK 5/6 and positive nuclear staining for P63
Malignant transformation of an epidermoid tumor into SCC is a rare but described phenomenon.[
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Conflicts of interest
There are no conflicts of interest.
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