Erythromelalgia presenting with posterior reversible encephalopathy syndrome: A pediatric case report

Background: Erythromelalgia is a rare disorder characterized by erythema, warmth, and burning pain in the extremities. We report a pediatric case of erythromelalgia in a patient who developed posterior reversible encephalopathy syndrome (PRES), without any cutaneous signs.
Case presentation: A previously healthy 12-year-old girl presented to our pediatric clinic with burning extremity pain that had persisted for 6 weeks. The patient was treated with analgesics; however, the pain was refractory to these agents. Seven days after the first visit, she developed afebrile seizures and was transferred to our hospital. Her initial blood pressure was 139/105 mmHg (+2.0 SD), and brain magnetic resonance imaging revealed high intensity areas in the bilateral parietal and occipital lobes, leading to a diagnosis of PRES. Her blood pressure was difficult to control with anti-hypertensive agents. Burning pain in her extremities was relieved by cooling and worsened by warming. Although erythema was not observed in her hands or legs, erythromelalgia was suspected based on the characteristic nature of her pain. Intravenous lidocaine was administered for diagnosis, which was dramatically effective. After initiating mexiletine, the burning pain in her extremities disappeared, and hypertension improved. A final diagnosis of erythromelalgia with PRES was made.
Conclusion: A history of temperature-dependent pain relief and deterioration are important indicators of disease diagnosis, even if patients indicate a lack of erythema or warmth. Physicians should be aware that persistent pain due to erythromelalgia can lead to refractory hypertension and development of PRES.