Atypical posterior reversible encephalopathy syndrome: A lentiform fork sign following transplantation.

Key Clinical Message: Posterior Reversible Encephalopathy Syndrome, typically characterized by parieto-occipital vasogenic edema, can present atypically, as a bilateral symmetrical vasogenic edema in the basal ganglia, featuring the called "lentiform fork sign." Prompt recognition of such variations is crucial for accurate diagnosis and tailored management, highlighting the complexity of this syndrome's manifestations.

Abstract: Posterior Reversible Encephalopathy Syndrome (PRES) manifests as transient neurological symptoms and cerebral edema, commonly associated with immunosuppressive drugs (ISDs) in transplant recipients. ISDs can lead to endothelial dysfunction and compromise the blood-brain barrier. Typically, PRES exhibits identifiable MRI patterns, often demonstrating vasogenic edema in the bilateral parieto-occipital white matter. Identifying unique presentations, such as the recently observed "lentiform fork sign," commonly seen in uremic encephalopathy, emphasizes this syndrome's broad spectrum manifestations. A 19-year-old male, who underwent bilateral lung and liver transplantation, experienced a bilateral tonic-clonic seizure of unknown onset 47 days post-surgery. MRI findings revealed an unconventional PRES pattern, featuring the "lentiform fork sign" as bilateral symmetrical vasogenic edema in the basal ganglia, surrounded by a hyperintense rim outlining the lentiform nucleus bilaterally. Subsequent management, including ISD modification and magnesium supplementation, resulted in clinical and neuroimaging resolution. An almost complete clinical and radiological resolution was achieved after 14 days. The occurrence of PRES in transplant recipients highlights the intricate interplay among ISDs, physiological factors, and cerebrovascular dynamics, potentially involving direct neurovascular endothelial toxicity and disruption of the blood-brain barrier. Neuroimaging plays a pivotal role in diagnosis. The distinctive "lentiform fork sign" was observed in this patient despite the absence of typical metabolic disturbances. Management strategies usually involve reducing hypertension, discontinuing ISDs, correcting electrolyte imbalances, and initiating antiseizure drugs if necessary. Identifying the presence of the "lentiform fork sign" alongside typical PRES edema in a patient lacking renal failure emphasizes that this manifestation is not solely indicative of uremic encephalopathy. Instead, it might represent the final common pathway resulting from alterations in the blood-brain barrier integrity within the deep white matter. Understanding such atypical imaging manifestations could significantly aid earlier and more precise diagnosis, influencing appropriate management decisions.