BACKGROUND: Acquired hemophagocytic syndrome (AHPS) is a severe inflammatory disorder often caused by Epstein-Barr virus (EBV). Proliferation of activated macrophages produces uncontrolled cytokine production. Thrombocytopenia is common in AHPS, previously attributed to inadequate or ineffective marrow platelet (PLT) production. PLT transfusion response is not well reported. Two patients with fatal AHPS developed unexplained PLT transfusion refractoriness before definitive diagnosis.

CASE REPORTS: PLT refractoriness was noted during the care of two patients. The refractoriness was determined to be nonimmune and both demonstrated various clinical signs and laboratory findings consistent with AHPS. The first patient's AHPS was attributable to EBV infection. In the other patient, no underlying cause could be found. Both patients had an aggressive clinical course and succumbed to this relatively rare syndrome. The PLT refractoriness was evident before the AHPS diagnosis was made.

DISCUSSION: AHPS is not generally a consideration in the evaluation of nonimmune PLT refractoriness. However, these illustrative cases make an argument for its consideration in the differential diagnosis of PLT refractoriness in severely ill patients. Once present, it is unclear if the refractoriness can be reversed by AHPS-targeted therapy.