Recurrent Epidermoid Cyst With Malignant Transformation Into Squamous Cell Carcinoma -Case Report-

Abstract

A 50-year-old male presented with a recurrent epidermoid cyst with malignant transformation into squamous cell carcinoma. The patient was first hospitalized for intermittent seizures in 2000. Computed tomography (CT) showed a hypodense lesion with enhanced capsule but no peripheral edema in the right temporal lobe. Craniotomy was performed and the lesion was completely removed. The histological diagnosis was epidermoid cyst. Six years later, the patient experienced blurred vision and hemiparesis in the left extremities. CT showed a hyperdense mass with peripheral edema in the right temporal lobe. Repeat CT 2 months later revealed a larger mass. The recurrent lesion was removed, and the histological diagnosis was squamous cell carcinoma. Intracranial epidermoid cyst is a benign tumor which often appears hypodense on CT, so change to hyperdensity in the recurrent tumor may indicate malignant transformation.

Clinical characteristics and diagnostic imaging of epidermoid tumors

“…17 Cyst contents are generally described as white, soft, structure-less, waxy/ cheesy debris, although epidermoid fluid has also been documented as thick, brown and viscous. 9,18 The lesion has a slow linear growth rate of one generation per month, similar to the turnover of normal human skin. 2,3,[19][20][21] However, rapid enlargement has been noted in unique cases of malignant transformation and hemorrhage.…”

“…Although the tumor effects are dependent upon lesion location, tumor extension and mass effect on adjacent vital structures, their presentation ranges from mild headaches to seizures and rare fatal events. 14,18,19,22,27,32 However, acute onset of symptoms is atypical, with a median duration of two to four years prior to presentation. 22 Trigeminal neuralgia is reported to be a primary symptom in 40% of cerebellopontine angle epidermoid cysts, as the lesion extends into the surrounding cisterns which are rich in neurovascular structures.…”

“…3,9,18,51 Hyperdense cysts (also referred to as ''white epidermoids'') are also uncommonly seen, with various etiologies suggested to describe their occurrence: increases in protein content, saponification of keratinized debris to calcium soaps, abundance of polymorphonuclear leukocytes, inclusion of blood components, and lipid debris. 6,14,18 New et al demonstrated an association between CT density and the protein concentration of cystic fluid. It has been further suggested that this increase in protein content is due to recurrent small leaks through the cyst wall which cause a proliferative and exudative response.…”

Epidermoid cyst of the posterior fossa: a case report

“…The lining epithelium of epidermoid cyst is immunoreactive for cytokeratins and epithelial membrane antigen (EMA). In contrast to cysts of neuroglial origin there is no immunoreactivity of the lining epithelium with antibodies to glial fibrillary acidic protein (GFAP) (2,4,6,8,13,14) .…”

Malignant transformation of an intramedullary epidermoid cyst in the thoracic region of the spinal cord

“…3 Malignant transformation of ECs to squamous cell carcinomas (SCCs) in the CNS is exceedingly rare and has only been described in intracranial ECs. 1,2,[5][6][7]10,12,14,15,20,23 We describe an intramedullary EC in the thoracic region that underwent malignant transformation 3 years after its removal. To our knowledge, this is the first reported case of a spinal EC undergoing malignant transformation.…”