Here’s a case with a classic, almost unmistakeable histologic appearance. I love that. Take a look at the photo and the question, then scroll down for the answer.

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:

  • Case 1: 20-year-old male who died suddenly
  • Case 2: 72-year-old male with right calf mass
  • Case 3: 67-year-old female with pancytopenia
  • Case 4: 59-year-old male with severe headaches
  • Case 5: 38-year-old female with deep venous thrombi
  • Case 6: 13-year-old male with cerebellar mass
  • Case 7: 45-year-old male with pulmonary emphysema
  • Case 8: 38-year-old male with AIDS and headaches
  • Case 9: 25-year-old male with arm mass
  • Case 10: 57-year-old male with fatigue and left upper quadrant heaviness
  • Case 11: 62-year-old male with hepatosplenomegaly, skin lesions and cardiomyopathy
  • Case 12: 16-month-old infant with failure to thrive
  • Case 13: 36-year-old female with painless lower leg nodule
  • Case 14: 58-year-old female with several-year history of pelvic pain
  • Case 15: 52-year-old male with abdominal pain and bloody diarrhea