Purpose of review
Neutropenia lasting for at least for 3 months and not attributable to drugs or a specific genetic, infectious, inflammatory, autoimmune or malignant cause is called chronic idiopathic neutropenia (CIN). CIN and autoimmune neutropenia (AIN) are very similar and overlapping conditions. The clinical consequences depend upon the severity of neutropenia, but it is not considered a premalignant condition.
Recent findings
Long-term observational studies in children indicate that the disease often lasts for 3–5 years in children, then spontaneously remits, but it rarely remits in adult cases. The value of antineutrophil antibody testing in both children and adults is uncertain. Most recent data suggest that CIN and AIN are immune-mediated diseases, but there are no new clinical or genetic tests to aid in diagnosis. Treatment with granulocyte colony stimulating factor (G-CSF) is effective to increase blood neutrophils in almost all cases; this treatment is reserved, however, for patients with both neutropenia and evidence of recurrent fevers, inflammatory symptoms and infections. There is little or no evidence to indicate that G-CSF treatment predisposes to myeloid malignancies in this population.
Summary
It is important to recognize CIN and AIN, the most common causes of chronic neutropenia in both children and adults. If the neutropenia is not severe, that is more than 0.5 × 109/l, most patients can be observed and not treated prophylactically with antibiotics or a growth factor. When neutropenia is severe, treatment with G-CSF is often beneficial.
