RPES has been identified in a wide range of hematologic conditions in adults and children, such as thrombotic thrombocytopenic purpura, hemolytic uremic syndrome (HUS), and also in acute or chronic renal failure, autoimmune diseases, and vasculitis [11]. Early clinical suspicion of RPES is crucial for early diagnosis, effective treatment, and good prognosis [12, 13].

The exact pathophysiology of PRES has yet to be clarified. About 70–80% are known to develop secondary to uncontrolled hypertension. Severe hypertension results in impaired cerebrovascular autoregulation, vasodilatation, and vasogenic edema. Literature reviews on hypertension and PRES widely discuss the “endothelial hypothesis” as the pathophysiological cause for a patient’s hypertension [14].

Notably, our patient was normotensive at presentation and on repeated blood pressure measurements throughout the duration of admission. The patient did not have any evident cerebral anoxia but had received PRBCs transfusion preceding this event.

Although the exact mechanism of PRES after blood transfusion is not clear, in chronic anemic conditions, rapid transfusion of large blood volumes is thought to induce PRES due to vascular autoregulation disruption, hyper-perfusion, and hyper-oxygenation, leading to cerebral harm [15]. In addition, high blood viscosity as well as long-standing hypoxia-induced vasodilatation results in an increase in the vascular resistance and may evoke an acute vascular endothelium dysfunction [15]. Nandi et al. [8] reported PRES after blood transfusion in 5-year-old child with hemoglobin E (HbE) β-thalassemia. Similar cases of PRES after blood transfusion were reported [5, 9, 10, 12, 16], and a case series in Japan [17], but none associated with β-thalassemia major.

MRI of our patient showed T2-FLAIR hyper-intensities typically symmetrical and bilateral involving parieto-occipital regions. However, involvement of the anterior brain, brainstem, basal ganglia, thalamus, and cerebellum has been previously reported (atypical MRI findings) [1,2,3].

The development of RPES in thalassemia might be multifactorial, and it is difficult to determine the role of each factor in precipitating its development and challenging to identify the exact underlying pathophysiology. In our patient, in the absence of hypertension, we speculate that blood transfusion was the underlying culprit of RPES (Fig. 3).

Postulated pathophysiology of PRES in thalassemia

The acute presentation and the complete recovery of our patient are noteworthy.

This highlight the fact that although PRES is considered a serious life-threatening disorder, it has an excellent prognosis with complete resolution if appropriate management is provided in the acute stage. More vigilance is crucial to early identify similar cases in practice. Further studies are still needed to investigate the exact pathogenesis and non-hypertensive mechanisms involved in this PRES, focusing on high-risk children with thalassemia.