Contributed by Daniel Martinez, MD and Nidhi Aggarwal, MD
A 3 month previously healthy female with no significant family history presented with a 2 day history of fever (38.8 °C) abdominal distention and tachypnea. Initial laboratory evaluation demonstrated pancytopenia with absolute neutropenia, elevated liver function tests, prolonged coagulation times, hyperlactatemia and elevated ferritin levels (Table 1). An infectious workup was negative (EBV, CMV, Adenovirus, Influenza, Parainfluenza, RSV, Chlamydia, Mycoplasma, Anaplasma and all cultures). A bone marrow biopsy was performed and demonstrated histiocytes with hemophagocytosis (Figure 1). Further testing demonstrated elevated soluble IL-2 receptor levels (>20000 pg/mL (Reference range: 622 to 1619 pg/mL). Subsequently genetic testing ordered was positive for biallelic mutations in PRF1.