REVERSIBLE ADULT-ONSET CYCLIC HEMATOPOIESIS WITH A CYCLE LENGTH OF 100 DAYS

Cyclic neutropenia is the most frequent of the cyclic haematopoietic disorders characterized by its regular 21 d cyclic fluctuations in the number of blood neutrophils, and in many cases simultaneous fluctuations in the other blood cell lines. In this paper we describe a 77-year-old woman with a cyclic pancytopenia including an the myeloid cell lines and to some extent the lymphocytes with a constant and predictable oscillation period of about 100 d. Serial bone marrow biopsies and plasma lactoferrin measurements indicated a similar fluctuating pattern in the bone marrow production of neutrophils. Serial measurements of plasma GM-CSF concentration pointed at a simple feed-back inhibitory system. The condition was present for at least 4 years, after which it gradually improved, although the thrombocyte count still showed a fluctuating tendency after.a further 4 years of observation. The clinical consequences were mild symptoms of anaemia and a few episodes of respiratory infections occurring during pancytopenic periods. We think this is the first case described in the literature with this variant of a cyclic haematopoietic disorder. The precise pathophysiological mechanism behind this condition is obscure, but probably it is due to a regulatory disturbance at a very early step in the haematopoietic stem cell hierarchy.