Progressive headache for 6 months.
MRI shows a well-circumscribed homogeneous mass lesion in pre-pontine and pre-medullary cistern with indentation on ventral surface of pons. The mass lesion shows homogenous hyperintense signal on T1W (Fig. 1) and hypointense signal on T2W images (Fig. 2). On DWI images, it demonstrates restricted diffusion (Fig. 3).
Intracranial epidermoid cysts are relatively common lesions, which account for approximately 0.2- 1.8% of all intracranial tumours. They result from inclusion of ectodermal elements at the time of neural tube closure. The cerebello-pontine angle is the most common location, but they are also seen in the 4th ventricle, sellar and para-sellar region.
The majority of patients are asymptomatic; however, headache, cranial nerve deficits, seizure and cerebellar symptoms are the usual complaints in symptomatic patients.
On CT scan they appear as hypodense, non-enhancing mass lesion with density similar to CSF, calcification may be present in 10-25% of patients.
MRI shows hypointense to isointense signal on T1 (isointense to CSF) and hyperintense signal on T2 weighted images, they do not suppress completely on FLAIR sequence. DWI images demonstrate characteristic restricted diffusion (appear bright). No enhancement is noted in the majority of epidermoid cysts, however, some may shows thin peripheral rim enhancement .
Complete surgical excision of the cyst was done in our patient. Histopathological examination showed features of epidermoid cyst (Keratinizing squamous epithelium in laminated pattern with fibrous connective tissue).
White epidermoid is an unusual version of epidermoid cyst. Due to high triglyceride and unsaturated fatty acid contents, it shows hyperintense signal on T1W MRI images as opposed to hypointense signal shown by the usual variety of epidermoid cysts [1, 2].
The majority of patients do not require any treatment, but in case of symptoms, surgical excision is the treatment of choice.
Differential Diagnosis List