To illustrate an atypical presentation of neurosarcoidosis, a known mimicker of several well-known neurological conditions.

50-year-old African-American female with no significant past medical history presented with three months of worsening vision in the left eye.  Visual acuity was 20/100 OS with an afferent pupillary defect, severe disc edema, hyperemia, and few disc hemorrhages. The rest of her clinical examination was unremarkable. MRI orbit showed left optic nerve enhancement. MRI brain revealed minimal, scattered, nonspecific T2 hyperintensities not consistent with multiple sclerosis. MRI C-Spine showed a 1.6 cm intradural, extramedullary, enhancing mass at the C5 level with spinal cord displacement but no cord signal change. Similar masses were seen at the T4, T10 and L3 levels, some of which extended into the neural foramina and along nerve roots.  Serologic testing for HIV and tuberculosis were negative. Basic CSF studies and cytology were normal. Serum ACE levels were normal.  IgG4 was low (IgG subclasses were normal). ANA was 1:640 with a homogeneous pattern.  CT chest was normal.

Neuro-ophthalmology examination revealed the presence of an infiltrative lesion on the optic nerve head, consistent with an infiltrative optic neuropathy.  Radiographic differential diagnosis for the spinal masses included schwannomas, paragangliomas, meningiomas and neurofibromas. IgG4 syndrome was considered, but she did not have prior history of thyroid disease, pancreatitis or lymphadenopathy. She was treated for optic neuritis with 5 days of IV methylprednisolone followed by an oral steroid taper. Biopsy of a spinal mass was scheduled.

Biopsy of a thoracic nerve root spinal mass showed neural tissue with associated non-caseating granulomatous inflammation.  This confirmed the diagnosis of neuro-sarcoidosis, and the patient was started on Methotrexate.

Unusual CNS masses or infiltrative lesions should prompt an aggressive approach for a tissue diagnosis. Neuro-sarcoidosis is known to mimic several well-known neurological conditions, as illustrated in this case.