A 49-year-old male patient manifested acute onset increased imbalance, quadriparesis, and speech impairment 1 month after undergoing ventricular-peritoneal shunt for normal pressure hydrocephalus (although magnetic resonance imaging [MRI] of the brain with contrast was otherwise normal), which showed improvement afterward. He had hypercalcemia and elevated erythrocyte sedimentation rate. Repeat brain MRI revealed pachymeningitis coupled with rhombencephalitis, while cerebrospinal fluid study unveiled only increased protein level without evidence of active infection. Given these findings, neurosarcoidosis was preliminarily considered a plausible cause of the recent clinical manifestations, and the patient was prescribed methylprednisolone, which led to significant improvement. However, the steroid treatment was discontinued on the revelation that the patient grappled with severe sepsis. Despite an initial improvement following a post-management of sepsis, his condition deteriorated, and he became lost to follow-up after 4 months of initial presentation. An infective etiology was ruled out since his condition improved with steroid. Precluding vasculitis or demyelinating disorder left the physicians with primary central nervous system (CNS) lymphoma or sarcoidosis as a proper diagnosis based on the fact that the patient experienced deterioration when steroid was excluded from the treatment regimen. This case study portrays a need to conduct a more specific and elaborate investigation, driven by a strong perception to both primary CNS lymphoma and sarcoidosis, to optimize clinical diagnosis, which facilitates the formulation of an appropriate treatment regimen.