A Rare Case of Hemophagocytic Lymphohistiocytosis and Macrophage Activation Syndrome in Settings of Etanercept Use and Epstein-Barr Virus Infection.

Hemophagocytic lymphohistiocytosis (HLH) is a rare syndrome in which widespread activation of the immune system leads to a state of excessive inflammation causing tissue damage. While this condition is mainly established in the pediatric population; due to its rarity, physicians often do not suspect this condition in adults. However, while diagnostic criteria are based on protocols tailored for the pediatric society, recognizing this condition in a timely manner in adults is utterly important to prevent a dismal prognosis. In instances where a concomitant rheumatological disorder is present, the syndrome is referred to as macrophage activation syndrome (MAS). This report describes a case of an adult patient who presented with mucosal bleeding and abdominal pain who was later diagnosed with MAS.