A 22-year-old woman develops psychiatric symptoms, seizures, dyskinesias, and autonomic instability over two weeks. CSF studies show lymphocytic pleocytosis, and antibodies against the NMDA receptor are detected. Pelvic ultrasound reveals a unilateral adnexal mass containing fat and calcification. What is the most likely underlying lesion?

• A Serous cystadenocarcinoma of the ovary
• B Granulosa cell tumor of the ovary
• C Dysgerminoma of the ovary
• D Mature cystic teratoma of the ovary ✓

Explanation

Anti-NMDA receptor encephalitis is a classic paraneoplastic neurologic syndrome associated with mature cystic teratomas of the ovary, in which neural tissue within the teratoma expresses NMDA receptor subunits and triggers autoantibody production. Fat and calcification on imaging are characteristic of a dermoid cyst. Dysgerminoma is associated with elevated LDH and OCT3/4 positivity but not this syndrome, which eliminates option C.

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.