Human parvovirus B19-induced acquired pure amegakaryocytic thrombocytopenia Acquired pure amegakaryocytic thrombocytopenic purpura is a relatively rare bone marrow failure disorder characterized by severe thrombocytopenia with total absence or marked reduc- tion of bone marrow megakaryocytes in the absence of other haematological abnormalities (Hoffman, 1991). We report a case of acquired pure amegakaryocytic thrombocytopenia secondary to parvovirus infection, which was treated with intravenous immunoglobulin. A 9-month-old male child was noticed to have skin purpura in late November 2003, of 2 weeks duration, followed by epistaxis and haematochezia. He had developed a cough a week prior to the other symptoms. The child developed an intracerebral bleed and was found to have a platelet count of less than 10 · 10 9 /l. Blood counts: Hb 10.9 g/dl, reticulocyte counts 0.4%, white blood cells (WBC) 9.8 · 10 9 /l, neutrophils 44%, absolute neutrophil count (ANC) 4.31 · 10 9 /l, platelet counts 9 · 10 9 /l. Bone marrow examination showed the absence of megakaryocytes with a prominence of lymphoid cells and a large number of haematogones with normal erythroid and myeloid precursors. Treatment was started with steroids and intravenous immunoglobulin (IVIG). Further investigations showed a positive Parvovirus B19 serology for both IgG and IgM by enzyme-linked immunosorbent assay (ELISA) and the bone marrow was positive for parvo DNA by polymerase chain reaction (PCR). Haemoglobin electro- phoresis showed : Hb F 1.7%, Hb A2: 2.8%, Hb A 85.2%. Glucose-6-phosphate dehydrogenase was normal. A peripheral blood smear showed normocytic normochromic red cells, no spherocytes or fragmented cells and no evidence of haemolysis. Immunoglobulin levels were normal. Screening for human immunodeficiency virus (HIV) type 1 and 2, toxoplasma, rubella, herpes simplex virus 1 and 2, and cytomegalovirus (IgM) were negative. Repeat bone marrow in January 2004 showed few megakaryocytes with a platelet count of 450 · 10 9 /l and normal Hb and WBC count but parvovirus serology and PCR were still positive. Oral steroids were stopped and IVIG was continued once in 3 weeks for five cycles. The blood counts remained normal. In June 2004, bone marrow aspir- ation showed a normal population of megakaryocytes. The parvovirus B19 DNA was negative by PCR in both bone marrow and serum, while serology (IgM) was negative by ELISA. IVIG was stopped and the child was well at the last follow-up. Blood counts in September 2004 were: Hb 11.7 g/dl, reticulocytes 0.9%, WBC 11.8 · 10 9 /l; neutrophils 35%, ANC 4.13 · 10 9 /l, lymphocytes 60%, monocytes 3%, eosinophils 2%, platelets 180 · 10 9 /l. The association of thrombocytopenia with parvovirus infection is uncommon, and is usually combined with other cytopenias or associated with aplastic crises of haemolytic anaemias (Saunders et al, 1986). There is one case report of transient erythroblastopenia of childhood with megakaryocytopenia associated with parvovirus B19 infection, which resolved spontaneously (Nagai et al, 1992). To our knowledge, no case of human parvovirus-induced pure amegakaryocytic thrombocytopenia has been reported so far in the literature. Our case is unique as there was no underlying haematological abnormality or immunocompromised state. The diagnostic criteria of parvovirus infection are PCR positivity and IgM positivity in serology (Gallinella et al, 2003, Young & Brown, 2004), both of which were present in our patient. On follow-up, the negative PCR and fall in IgM suggest that the virus was eradicated, with a possible role for IVIG. Parvoviruses have a remarkable tissue tropism for erythroid elements in the bone marrow and are known to cause transient aplastic crisis in patients with various haemolytic anaemias (Young & Brown, 2004) but their relationship to platelets is not well documented. In vitro exposure of human bone marrow cells to parvovirus has been shown to significantly suppress megakaryocyte colony forma- tion (Srivastava et al, 1990). This may be the mechanism of amegakaryocytic thrombocytopenic purpura secondary to parvovirus. Parvovirus should be considered as a possible aetiological agent in amegakaryocytic thrombocytopenia, and IVIG may be of benefit. Jina Bhattacharyya 1 Rajat Kumar 1 Seema Tyagi 1 Janak Kishore 2 Manoranjan Mahapatra 1 V. P. Choudhry 1 1 Department of Haematology, All India Institute of Medical Sciences, New Delhi, India, and 2 Department of Microbiology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, India. E-mail rajatkr@hotmail.com References Gallinella, G., Zuffi, E., Gentilomi, G., Manaresi, E., Venturoli, S., Bonvicini, F., Cricca, M., Zerbini, M. & Musiani, M. (2003) Relevance of B19 markers in serum samples for a diagnosis of correspondence doi:10.1111/j.1365-2141.2004.05252.x ª 2004 Blackwell Publishing Ltd, British Journal of Haematology, 128, 128–129