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Parvovirus B19-associated hemophagocytic lymphohistiocytosis in a child with precursor B-cell acute lymphoblastic leukemia under maintenance chemotherapy.

Development of hemophagocytic lymphohistiocytosis (HLH) is quite rare among acute lymphoblastic leukemia (ALL) patients. We present a 3-year-old boy with precursor B-cell ALL, who was complicated by HLH because of parvovirus B19 infection during maintenance chemotherapy. Remarkable erythroid hypoplasia, giant normoblasts, and hemophagocytosed macrophages in bone marrow were important clues for the diagnosis. The patient was successfully treated with high-dose steroids and intravenous immunoglobulins. To our knowledge, this is the first report describing parvovirus B19-associated HLH in ALL. Our case highlights that parvovirus B19 can cause HLH, a potentially fatal disorder, and prolonged unexpected cytopenia in childhood ALL.