A 55-year-old woman presents with progressive unilateral sensorineural hearing loss, tinnitus, and imbalance. MRI reveals a well-circumscribed, enhancing mass at the cerebellopontine angle extending into the internal auditory canal. Histology shows alternating hypercellular Antoni A areas with Verocay bodies and hypocellular Antoni B areas. Which immunostain is most specific for this tumor?
- A GFAP
- B S100 ✓
- C EMA
- D Synaptophysin
Correct answer: B. S100
Explanation
This describes vestibular schwannoma (acoustic neuroma), a benign nerve sheath tumor arising from Schwann cells of CN VIII. S100 is strongly and diffusely positive in schwannomas, unlike neurofibromas which are patchy. GFAP marks glial tumors. EMA marks meningiomas and perineuriomas. Synaptophysin is a neuroendocrine marker. Schwannomas are associated with NF2 when bilateral.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.