Neuro-Myelomatosis of the Brachial Plexus – An Unusual Site of Disease Visualized by Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography (FDG-PET/CT): A Case Report

Patient: Female, 63 Final Diagnosis: Extramedullary involvement of multiple myeloma Symptoms: Right shoulder/upper arm, neuropathic pain Medication: High-dose dexamethasone therapy Clinical Procedure: FDG PET/CT Specialty: Hematology • Nuclear Medicine OBJECTIVE: Rare disease BACKGROUND: Peripheral or cranial nerve root dysfunction secondary to invasion of the CNS in multiple myeloma is a rare clinical event that is frequently mistaken for other diagnoses. We describe the clinical utility of (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET)/CT scanning for diagnosing neuro-myelomatosis. CASE REPORT: A 63-year-old woman whose chief complaints were right shoulder and upper extremity pain underwent MRI and (18)F-FDG PET/CT scan. MRI revealed a non-specific brachial plexus tumor. (18)F-FDG PET/CT demonstrated intense FDG uptake in multiple intramedullary lesions and in the adjacent right brachial plexus, indicating extra-medullary neural involvement associated with multiple myeloma, which was confirmed later by a bone marrow biopsy. CONCLUSIONS: This is the first reported case of neuro-myelomatosis of the brachial plexus. It highlights the utility of the (18)F-FDG PET/CT scan as a valuable diagnostic modality.