Cranial Nerve III Palsy as the First Sign of Carcinomatous Meningitis From Non-Hodgkin's Lymphoma.

Carcinomatous meningitis (CM) is characterized by the multifocal dissemination of malignant cells into the cerebrospinal fluid (CSF), pia mater, and subarachnoid space. Involvement can occur in the advanced stage of malignancy, causing multifocal involvement and a wide array of symptoms. Diagnosis requires suspicions and a multimodal approach that includes imaging, lumbar puncture, and diagnostic laboratory evaluation. This case represents a female with a history of non-Hodgkin's lymphoma (NHL) and venous thromboembolism on chronic anticoagulation who presented due to acute encephalopathy, hallucinations, and right cranial nerve III palsy for 10 days before arrival. Computed tomography (CT) and angiography of the brain did not show any intracranial abnormalities. Subsequent magnetic resonance imaging (MRI) was without signs of infarction, hemorrhage, or abnormal enhancement, with the MRI of the orbits showing asymmetric linear enhancement anterior to the superior pons and midbrain on the right. Initial differential included a paraneoplastic syndrome, but there was no obvious evidence of pathological enhancement on MRI. Due to progressive bulbar symptoms, a lumbar puncture was performed with cerebrospinal fluid diagnostic workup with cytology showing monoclonal B-cell proliferation consistent with lymphoma. This case illustrates a rare but specific finding of CM as cranial nerve III palsy symptoms in this patient who did not have imaging findings that would reflect her symptoms on the initial MRI of the brain. Furthermore, diagnosing CM is complex and involves a combination of multiple diagnostic and treatment modalities. It is important to recognize the condition early to improve the patient's quality of life, prolong survival, and stabilize neurological deterioration.