Microfilariae in bone marrow aspirate of a case of myelofibrosis: A cause or coincidence?

Filariasis is among the common parasitic infestations found in India, with Wuchereria bancrofti being the most common causative organism. Presentation ranges from clinically asymptomatic to profound elephantiasis. It is also detected incidentally in diagnostic samples such as body fluids, fine needle aspirates, peripheral blood smears, and other cytological smears. Its detection in bone marrow aspirates with an associated hematolymphoid neoplasm is rare, with only a few case reports. We report one such case of young male who presented with leukocytosis of 253 × 109/L with basophilia and massive splenomegaly. Bone marrow aspirate smears showed the presence of microfilariae along with other features of a myeloproliferative neoplasm (MPN). The present case is probably the first case of finding a microfilaria in a case of MPN.