RT Journal Article SR Electronic T1 Castleman disease with follicular dendritic cell sarcoma presenting with pseudotumor cerebri and myasthenia gravis (P5.189) JF Neurology JO Neurology FD Lippincott Williams & Wilkins SP P5.189 VO 88 IS 16 Supplement A1 Fein, Alexander A1 Bittar, Humberto Trejo A1 Shende, Manisha A1 Scalzetti, Ernest A1 Ko, Melissa YR 2017 UL http://n.neurology.org/content/88/16_Supplement/P5.189.abstract AB Objective: This case highlights a rare combination of pseudotumor cerebri (PTC), myasthenia gravis (MG), and Castleman disease (CD).Background: Castleman disease is a lymphoproliferative disorder that has previously been associated with PTC or MG. This is a rare case of CD with follicular dendritic cell sarcoma (FDCS) presenting with PTC and subsequently MG.Design/Methods: Case study report.Results: A 21-year-old woman presented with headache, blurred vision and pulsatile tinnitus in the setting of recent weight gain. On exam, she demonstrated VA: 20/20-1 OU, bilateral optic disc elevation, and noted blind spot enlargement OD. MRI brain was within normal limits. Lumbar puncture showed an elevated opening pressure of 38 cm of water with normal CSF composition and a diagnosis of pseudotumor cerebri was made. Acetazolamide was initiated along with a weight loss regimen. On follow-up, she had lost 18 lbs with resolved symptoms and papilledema. However, she reported new symptoms including facial asymmetry and fatigue with extended speech and reading. Due to worsening dysphagia and facial weakness, acetylcholine receptor antibodies were obtained and noted to be elevated. A diagnosis of myasthenia gravis was made, and pyridostigmine was initiated. A CT thorax with contrast was obtained revealing a posterior mediastinal mass. Upon resection, histology of the mass showed follicular dendritic cell sarcoma in the setting of hyaline vascular Castleman disease. The patient has been asymptomatic following treatment with IVIG, pyridostigmine and acetazolamide.Conclusions: To our knowledge, this is the first reported case of unicentric CD with FDCS presenting with PTC and MG. A potential unifying pathophysiology could involve the elevation of interleukin-6, which has been previously described to contribute to lymphoproliferation associated with cases of CD and CD with MG. Elevated IL-6 levels in serum and CSF have been noted in PTC, which may be a linking factor to CD or an epiphenomenon.Disclosure: Dr. Fein has nothing to disclose. Dr. Trejo Bittar has nothing to disclose. Dr. Shende has nothing to disclose. Dr. Scalzetti has nothing to disclose. Dr. Ko has nothing to disclose.