A case of multiple myeloma (IgA-lambda) with marked granulocytosis, wh
ich measured up to 9.9x10(4)/mm(3), is described. Matured neutrophiles
were predominant and blasts were not found in the peripheral blood. T
he serum granulocyte colony-stimulating factor (G-CSF) was notably ele
vated. The disease ran a chronic course and granulocytosis and elevate
d serum G-CSF continued. The patient developed atelectasis and broncho
pneumonia, and died of respiratory failure. At autopsy, bone marrow sh
owed marked myeloid hyperplasia in varying states of differentiation.
The enlarged spleen also disclosed numerous myeloid cells of varying d
ifferentiation. Small aggregations of atypical plasma cells were prese
nt in the marrow and spleen. Immunohistochemically, atypical plasma ce
lls were positive for anti-G-CSF antibody, which indicated G-CSF secre
tion from the myeloma cells. To our knowledge, this is the first repor
ted case of G-CSF-producing multiple myeloma.