Malignant transformation six months after removal of intracranial epidermoid cyst: a case report

Abstract

Intracranial epidermoid cysts are uncommon benign tumors of developmental origin; malignant transformation of benign epidermoid cysts is rare, and their prognosis remains poor. We report a case of squamous cell carcinoma arising in the cerebellopontine angle. A 52-year-old man presented with left facial paralysis and cerebellar ataxia. He had undergone total removal of a benign epidermoid cyst six months previously. Postoperative magnetic resonance imaging of the brain revealed a heterogeneous and cystic lesion in the left cerebellopontine angle with hydrocephalus. The cyst wall was enhanced by gadolinium. He underwent ventricle-peritoneal shunt and removal again; the histopathological examination revealed a squamous cell carcinoma possibly arising from an underlying epidermoid cyst. This entity is being reported for its rarity. The presence of contrast enhancement at the site of an epidermoid cyst combined with an acute, progressive neurological deficit should alert the neurosurgeon to the possibility of a malignant transformation.

Figure 1

Axial (a) and sagittal (b) T1-weighted MRI with gadolinium and axial (c) T2-weighted MRI before surgery revealing a large cystic lesion of left CPA with enhancement of lower portion of the lesion and severe compression of forth ventricle and brainstem.

Figure 2

Axial (a) T1-weighted MRI with gadolinium and coronal; (b) T2-weighted MRI after the first surgery showing growth of the heterogeneous lesion with predominant enhancement and invading the surrounding structures.

Figure 3

Malignant squamous cell carcinoma arising from the epidermal cyst, with mitotic activity and cellular atypia (hematoxylin and eosin, original magnification ×400).