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Objective: Collision tumors of the skull base are rare lesions that frequently arise in neurofibromatosis-2
(NF2) patients. They are known to exhibit accelerated growth rates and behave more
aggressively. Gross total resection is not often feasible due to the high morbidity
of cranial nerve palsies. Management from a technical and decision-making standpoint
can be very challenging, though little research or guidance is available on this topic.
Methods: Consecutive patients with an intracranial, skull base tumor treated by the senior
author were queried using a prospective database at a tertiary care medical center.
Dates ranged from January 2009 to March 2023. Those that had at least two distinct
masses found to have a histological diagnosis consistent with a collision tumor and
were 4 cm or greater in size were included. Collision tumors 4 to 4.99 cm were categorized
as “giant” while tumors 5 cm or greater were categorized as colossal.
Results: A total of 26 surgeries were performed on 11 patients. Most were in the third decade
of life at the time of evaluation (mean: 26 years, range: 19–35). Mean tumor size
was 5 cm (range 4–7.7 cm); 4 (36%) were considered colossal and 7 giant (64%). Sixty-four
percent had either prior radiation or surgery at the skull base before initial evaluation.
Gross total resection was not feasible in any of the cases. Eight revision surgeries
were performed, which averaged every 4.6 years (range: 0.8–14.6, median: 3.9 years).
Kaplan–Meier estimates for 5-year revision-free time after surgery was 65% and 10-year
survival was 88%. The majority of patients had a Karnofsky score of 70% (6/11) at
the time of most recent follow-up ([Figs. 1]–[4]).
Conclusion: Gross total resection was not feasible for NF2 patients without significant morbidity
for colossal and giant collision tumors of the skull base. We found a strategy of
palliative, serial debulking afforded sufficient time between repeat surgeries and
with an acceptable quality of life.
