Neurolymphomatosis mimicking a Guillain-Barré syndrome triggered by COVID-19 vaccination.

Guillain-Barré syndrome (GBS) is an acute disorder of the peripheral nervous system, causing flaccid paralysis, areflexia, and variable sensory involvement. Proximal as well distal muscles of the limbs can be involved, and in most severe and advanced cases progresses to respiratory failure and death. GBS is considered an autoimmune disease, and at the basis of the attack at the peripheral nervous system different mechanisms have been recognized, in particular viral infections or other immune stimulations. Cranial nerve involvement in patients with diffuse large B-cell lymphoma (DLBCL) and primary central nervous system lymphoma are rare conditions that could present with similar clinical features. Here we present a case of a 36-year-old man hospitalized for acute polyradiculoneuritis of the cranial nerves and lumbar roots that arose a 14 days after severe acute respiratory syndrome COVID-19 2 (Sars-CoV-2) vaccination. Most of the main criteria for the diagnosis of GBS were met, including clinical and electrophysiological criteria. Albuminocytologic dissociation and high protein level in cerebrospinal fluid were also found. Therefore, the patient was treated with a cycle of intravenous immunoglobulin (IVIG) with notable improvement of symptoms and gradual recovery of motility. A five months later, following SARS-CoV-2 infection, the patient presented with worsening of neurological symptoms and was readmitted to the hospital. He underwent instrumental tests again and was treated with repeated cycles of IVIG and then with a cycle of plasmapheresis without any improvement. In the following 10 days he developed very serious conditions; he was transferred to intensive care unit and deceased after 6 days. The cause of the neurological syndrome was determined only after autoptic analysis, which revealed the presence of primary peripheral nervous system (PNS) DLBCL. The reported case highlights that GBS-like presentation always requires a careful differential diagnosis, and physicians should also consider the possibility of an occult cancer.