Cyclical eosinophilia: a manifestation of periodic haemopoiesis?

A patient is described who has had a marked eosinophilia of unknown cause for 9 years in association with episodic facial swelling. Weekly blood counts for 8 months showed cyclical variations in eosinophils, neutrophils and monocytes (mean cycle length 35 d). Marrow culture studies showed fluctuation in the incidence of granulocyte-macrophage colonies (GM-CFC), and the proportion of eosinophil colonies was higher than the values reported for normals. The blood lymphocyte T4/T8 ratio was reversed, due to an increase of T8+ cells. It is suggested that this condition is a rare form of periodic haemopoiesis.