A 77-year-old male presented with 8 months of progressive left facial pain and weakness. His medical history was significant for CLL diagnosed 9 years prior. He was treated with chemotherapy, with his CLL felt to be inactive for the last 8 years.  

His neurologic exam was significant for impaired pinprick sensation of the left half of the face, with left facial weakness in a lower motor neuron pattern. MRI brain with and without contrast was ordered, revealing a 2 x 1 cm area of enhancement within the left Meckel’s cave, extending into the left prepontine cistern, with adjacent pachymeningeal enhancement. LP was completed with normal CSF analysis including flow cytometry and cytology. A CT of the chest/abdomen/pelvis showed widespread lymphadenopathy, with later lymph node biopsy consistent with SLL. Despite negative CSF flow cytometry, he was diagnosed with SLL with CNS involvement based on imaging characteristics and clinical history.