RESUMEN
Neurolymphomatosis, the infiltration of the peripheral nervous system (PNS) by malignant lymphatic cells, is a rare condition whose prognosis and treatment are not fully characterized. The authors report the case of a 69-year-old, previously healthy man who had a 1-month history of progressive pain in his right arm and associated weakness of several muscles of the right upper extremity when they first examined him. Initial MR imaging of the right brachial plexus showed no abnormalities, but over 3 months, symptoms gradually progressed to almost complete plegia of his right upper extremity. Subsequent MR imaging of his right brachial plexus showed an enhancing mass of the posterior cord of the plexus that encroached on the other cords. Positron emission tomography confirmed the presence of a hypermetabolic lesion in the right axillary region and also detected an asymptomatic hot spot in the gastric wall. Biopsy of the gastric lesion demonstrated a CD20+, diffuse large B-cell lymphoma that was immunohistochemically positive for BCL-6 and negative for p16. The patient underwent 6 cycles of dose-adjusted etoposide-vincristine-doxorubicin-cyclophosphamide-prednisone (EPOCH) and rituximab, intermixed with 3 cycles of high-dose intravenous and intrathecal methotrexate, and followed by 6 monthly doses of rituximab for consolidation. Follow-up MR imaging and PET of the plexus showed complete radiological response after 3 months of treatment, as demonstrated by normalization of brachial plexus caliber, contrast enhancement, and metabolic activity. Twenty-eight months after symptom onset and 20 months after beginning therapy, the patient was disease-free, had recovered most upper extremity neurological function, and had only minimal remaining weakness of the right wrist and finger extension.