New paraneoplastic syndrome in chronic basophilic leukemia.

Chronic basophilic leukemia (CBL) is an extremely rare disorder. A female patient presented with recurrent attacks of chills, fever and abdominal pain was found to have simultaneous cyclic oscillation in leukocyte counts and C-reactive protein values. She was initially diagnosed with familial Mediterranean fever and treated with colchicine. Diagnosis of CBL was established by morphologic studies of peripheral blood and bone marrow. Her febrile attacks recurred with marked elevation in serum interleukin-6 (IL-6) level when basophil counts climbed to peak levels during cyclic oscillation. Molecular studies by real-time PCR showed IL-6 gene expression in neoplastic basophils separated by magnetic-activated cell sorting infiltrating the bone marrow, suggesting that IL-6 is released by neoplastic basophils of an underlying CBL, resulting in a new paraneoplastic syndrome that mimics autoinflammatory disorders.