It is an honor for having been invited to write a commentary/guest editorial to the
published paper titled, “Analysis of giant intraventricular and extraventricular epidermoids,
defining risk factors for recurrence, an institutional experience.”[[1]] The current paper explicitly explains risk factors for recurrence in multi-compartment
epidermoid tumors. The authors have provided a well-designed study and analysis to
determine valuable preoperative information. Such information would clearly help surgeons
to make timely decisions while attempting surgery on such critical cases. The patients
were categorized into three groups including multi- and single-compartmental lesions.
Tumors with preoperative capsular enhancement, multi-compartmental distribution in
vertebrobasilar territory, large size, and presence of calcification have been cited
as strong predictors for recurrence. It has also been claimed that endoscope-assisted
surgery could reduce the risk of morbidity; however, the recurrence rate was not changed.[[1]]
According to the contemporary literature, there is no effective chemotherapy; moreover,
radiotherapy has indication only in recurrent unresectable cases and furthermore carries
the risk of malignant transformation of the residual tumor into squamous cell carcinoma.
Therefore, surgical resection remains the mainstay of treatment.[[2]],[[3]]
Epidermoid tumors typically occur and expand within cisterns and fissures, spreading
through various corridors, often along the skull base.[[2]] The capsule is adherent to neurovascular structures in the majority of cases, which
mandates conservative management. Therefore, the capsule would be left without manipulation
to prevent major deficits and recurrence becomes inevitable. Sometimes, surgical resection
of the recurrent tumor could be really challenging.[[2]],[[3]]
Natural history plays a significant role. Considering the age of the patients is critical
in decision-making and subtotal resection would be justified in old cases with severe
comorbidities. Some claim that total removal of the capsule prevents or delays recurrence
and minimizes complications and improves long-term outcomes.[[2]],[[4]] Therefore, preoperative planning and intraoperative decision-making are valuable
in such patients. Moreover, several factors would assist in the prediction of recurrence.
Mass reduction of cyst contents in most cases usually results in marked improvement
of the symptoms. However, although the number of the cases is limited, the strangulation
of the affected nerves by the tumor capsule, not the cyst pressure, causes distortion
of the nerve axis and nerve atrophy distal to the strangulation site, resulting in
preoperative rapid and severe dysfunction. This mechanism has been reported with the
sixth and seventh cranial nerves in cerebellopontine angle epidermoid cyst,[[5]] and young age and rapidly progressive neurological deficit might be the characteristics
for strangulation of the affected nerves by the cyst capsule. A similar strangulation
mechanism causing the trigeminal neuralgia as well has been reported.[[6]] In such cases, immediate decompression and release of the strangulating band of
the epidermoid cyst wall might be essential to ameliorate the rapidly evolving deficit.
It is important to understand ways to optimize the extent of epidermoid tumor resection
in an effort to prevent a recurrence. Some claim that total removal (gross total resection
[GTR]) of epidermoid would decrease the overall rate of morbidity. Others believe
that aggressive resection of tumor capsule challenges GTR.[[2]],[[3]] It seems that the removal of proliferative capsules minimizes the risk of regrowth.
This has been supported by the significant difference in recurrence rates between
subtotal and GTRs.[[3]]
Moreover, there is a high risk of aseptic meningitis and cranial nerve injury which
challenge modern microsurgical techniques and surgical expertise. Intraoperative monitoring
and intraoperative magnetic resonance imaging are important adjuncts to improve the
visualization of tumor and extent of surgical resection.[[3]],[[4]] Furthermore, the use of the endoscope has been of tremendous help in visualizing
the tumor along the skull base, especially in multi-compartmental lesions.[[4]]
On the other hand, scar tissue and adhesions increase the risk of recurrent surgery.
The capsule could be totally removed in about 70% of primary cases, in comparison
to 17% of reoperations.[[3]],[[4]] Therefore, decision-making about the resection of capsule requires an individualized
decision-making. GTR with capsule resection is achievable in the majority of patients;
however, safe and maximal resection is always a justified and coveted goal.
