Squamous Cell Carcinoma Arising in a Remnant of an Extirpated Cerebellopontine Angle Epidermoid Tumor: Case Report and Literature Review

Objective: The authors present the case of a woman with a cerebellopontine angle (CPA) epidermoid tumor with malignant transformation into a squamous cell carcinoma. Primary intracranial squamous cell carcinoma is a rare occurrence. When encountered, they often appear to arise from a preexisting benign epidermoid cyst.

Patient: In May 2012, a 73-year-old woman presented to Thomas Jefferson University Hospital for Neuroscience. She had previously undergone subtotal resection of a right CPA epidermoid tumor in 1999. This was followed by fractionated sterotactic radiotherapy for a total dose of 50.4 Gy from December 2000 to February 2002 due to reoccurrence of the tumor as seen on imaging. The patient was asymptomatic until May 2012, at which time she presented with progressive neurologic symptoms including; dysarthria, dysphagia, hoarseness, and stridor. MRI demonstrated a new enhancing mass in the right CPA with extension to C1.

Intervention/Results: A far-lateral craniectomy and a right C1 hemi-laminectomy were performed to relieve the mass effect on the brainstem, as well as a subtotal resection of the recurrent CPA tumor. Histological analysis of the excised tumor revealed squamous cell carcinoma with focal adenosquamous differentiation. Postoperatively, it was suggested that she undergo re-irradiation to the area; however, the patient died shortly thereafter.

Conclusion: Malignant degeneration of CPA epidermoid tumors should be considered in the presence of rapidly progressing neurologic deficits and MR enhancement on imaging. Although the tumor can be temporized with a combination of surgery, external beam radiotherapy, and stereotactic radiosurgery, long-term prognosis remains poor.