Herein, we present a rare and diagnostically challenging case of neuro-Behcet disease (NBD) manifesting as a psuedotumoral brainstem mass. 

Psuedotumoral-NBD as a neurologic manifestation of Behcet’s disease is rare. Imaging is characterized by mass-like lesions that enhance with contrast, are hyperintense with T2-weighted and fluid-attenuated inversion recovery (FLAIR) and show restricted diffusion. The differential includes glial lesions, lymphomas, infectious and granulomatous lesions. 

A 33-year-old male of West-African descent with a history of Behcet’s disease, presented two years after his diagnosis with headaches, low-grade fever, genital ulcerations, and horizontal binocular diplopia. Imaging revealed a large right-sided T2/FLAIR hyperintense abnormality in the medulla with a central area of necrosis.  Cerebrospinal fluid revealed lymphocytic-predominant pleocytosis with 11·10⁶ cells/L (reference range 0-5), and high levels of interleukin-6. His vasculitis, infectious, paraneoplastic, flow cytometry, and autoimmune panels were negative. He tested positive for hepatitis-B core antigen, and latent tuberculosis. The etiology for his presentation was believed to be parenchymal NBD and he received a 3-day course of intravenous solumedrol (eventually transitioned to prednisone and azathioprine) with significant improvement. Imaging 1-week post-treatment revealed resolution of enhancement, and at 3 months he had near complete lesion resolution. 

NBD can rarely present with a psuedotumoral presentation, which can cause diagnostic uncertainty. A thorough radiologic/laboratory workup should be conducted to exclude other neurologic diagnoses; however, a high index of suspicion for NBD is required in similar cases and a spectacular response to steroids are invaluable in diagnosis.