Infection-associated haemophagocytosis: the tropical spectrum.

Reactive proliferation and inappropriate activation of mature histiocytes with haemophagocytosis (HP) may occur in association with a wide variety of infections, neoplasms, collagen vascular diseases, and acquired and inherited immunodeficiency states. The association with infections is particularly important because overwhelming HP can obscure the typical clinical features of the primary disease and negatively affects outcome. A high index of suspicion is required for early recognition of associated HP as the cause of cytopenias. Institution of specific therapy is crucial for survival. This study highlights the wide spectrum of tropical diseases that can have associated reactive HP. Thirty cases with documented prominent HP on bone marrow aspiration smears were reviewed. Twenty-one (69%) of the marrows were from patients who had common tropical infections: malaria, typhoid and visceral leishmaniasis and 11 of 15 patients (73%) who were followed up improved on specific infection-directed and supportive measures. The presence of severe HP in bone marrow smears correlated with marked cytopenias. Recognition of HP in this geographical region should stimulate the search for one of these infections as early institution of specific therapy is crucial for patient survival.