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

## TL;DR

A rare case of PRES in a transplant recipient showed an unusual MRI pattern called the 'lentiform fork sign', highlighting the need for tailored diagnosis and treatment.

## Contribution

Describes an atypical PRES manifestation with the 'lentiform fork sign' in a transplant recipient without typical metabolic issues.

## Key findings

- The patient showed a 'lentiform fork sign' on MRI, indicating bilateral symmetrical vasogenic edema in the basal ganglia.
- Clinical and radiological resolution occurred within 14 days after modifying immunosuppressive drugs and adding magnesium supplementation.
- The 'lentiform fork sign' was observed without typical metabolic disturbances, suggesting broader PRES manifestations.

## Abstract

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.

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.

Atypical posterior reversible encephalopathy syndrome (PRES) in transplant recipients. This study describes a case of PRES in a 19‐year‐old male following bilateral lung and liver transplantation. The patient presented with a bilateral tonic‐clonic seizure and exhibited an unconventional MRI pattern known as the “lentiform fork sign,” indicating bilateral symmetrical vasogenic edema in the basal ganglia. Management involving immunosuppressive drug modification and magnesium supplementation led to a significant clinical and neuroimaging resolution within 14 days. This case underscores the diverse manifestations of PRES, the pivotal role of neuroimaging in diagnosis, and the need for tailored management strategies in transplant recipients.