Intracranial epidermoid cysts/ tumors were first described by Bailey and Cushing in the early 1920s.
These account for 0.2– 1.8 % of all intracranial neoplasms and approximately 50 % of intracranial epidermoid cyst occurred in the cerebellopontine angle,
followed by parasellar region,
basal cistern,
sylvian,
pineal region and ventricle systems.
It is postulated to originate from epithelial remnants that remain after neural tube closure,
rarely acquired lesions are also reported.
It is usually benign unless is ruptured.
A lot of research has been done on these.
It has been found that these benign tumors are formed between third to fifth week of embryonic life.
It is due to displaced epithelial remnants.
These persist after neural tube closure.
Whenever two ectodermal surfaces fuse with eachother such as the skin,
epidural,intradiploic and epicranial surfaces,
these are formed.
These occur in isolation most of the times.
Their most common location is cerebellopontine angle which is found to be 37% but in our experience they are found most commonly in the region of fourth ventricle i-e rhomboid fossa.
Their second most common location is suprasellar region(31%),
diploic space(16%),
rhomboid fossa(11%) and spinal canal(5%).
Other lesser common locations are the pineal region,
thalami,
septum pellucidum and other intraparenchymal location.
They have been reported in lateral ventricle and we have reported one such case too.
Apart from these we found them in lacrimal gland too.
These have a benign and slow growth pattern.
They remain asymptomatic until and unless these cause obstruction.
The symptoms generally appear around 20-40 years of age.
The symptoms depend on the location of the lesion ranging from seizures,
dementia,
hydrocephalus to asymptomatic.
In case these are symptomatic,
main treatment is surgery.
Endoscopic debulking through suction catheter is performed in certain centres.
The surgery is simple as these are avascular but is difficult due to their complex locations.
Malignant degeneration is reported in epidermoids rarely and is detected due to contrast uptake of the remnant lesion. Hamlat et al. ,
reported that from the seventeen cases undergoing malignant degeneration,
six showed enhancement at the time of the initial CT study, indicating that post-contrast enhancement is an important indicator of aggressive change.
Uptil now a death of five patients is reported due to surgical complication by Roy et al.
Other complications include chemical meningitis,
cerebellar dysfunction and in few patients cranial nerve dysfunction.
Thus epidermoids are benign intracranial tumors which at times become a surgical dilemma due to their location.