What is the most likely diagnosis?
From which nerve do these usually arise?
Vestibular portion of the vestibulocochlear nerve (CN VIII)
What are two possibilities if these are present bilaterally?
Most likely the patient has neurofibromatosis type II (NF2). Some cases can be familial.
When these tumours are resected, what are the two most common surgical approaches, and what (largely) determines which is chosen?
Retrosigmoid approach is used when some hearing is preserved. This approach does struggle to get to the fundus of the acoustic meatus. Translabyrinthine approach sacrifices hearing.
MRI of the brain with contrast demonstrates a mass in the right cerebellopontine angle. It is heterogeneous in signal, enhances vividly, and extends a tongue of tissue into the internal acoustic meatus. It appears to be an isolated abnormality.