A 42 year-old female presents with tinnitus and hearing loss, and is found to have a mass at the cerebellopontine angle. A biopsy section is shown here.

 PS unknown 16-1

What is the most likely diagnosis?

A. Meningioma
B. Glioblastoma
C. Schwannoma
D. Medulloblastoma
E. Ependymoma






(Scroll down for the answer)








The diagnosis in this case is Schwannoma. Most schwannomas occur at the cerebellopontine angle, attached to the eighth nerve. In this setting, the tumor is often referred to (inaccurately) as an acoustic neuroma. It’s not a neuroma – it’s a tumor of nerve sheath cells (a schwannoma!). But old names die hard.

Schwannomas are usually well-circumscribed masses that are easily separated from the nerve to which they are attached. Yay! Good prognosis. Clinically, they are a common component of neurofibromatosis type 2 (but they can occur sporadically too).

Histologically, the appearance is very cool-looking and very characteristic. If you get this in an unknown conference, you’ll know it (now that you’ve seen it).

Schwannomas have a mixture of two architectural patterns: a densely cellular “Antoni A” pattern and a less cellular “Antoni B” pattern.

In the Antoni A pattern (as shown below), you see these elongated cells arranged in rows (fascicles) around a central zone containing cytoplasmic processes. Those central zones of processes between the regions of nuclear palisading are called Verocay bodies.

PS unknown 16-3

The Antoni B areas are less cellular and have a myxoid background, as shown below (you can see a little Verocay body on the right – but most of the field shows an Antoni B pattern):

PS unknown 16-2

Malignant change is extremely rare in these tumors, and the prognosis is excellent.

If you liked this case, and want to test yourself with other unknown cases, here are some to try:

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