Cyclic neutropenia is a rare cause of periodic fevers that occur during periodic drops in the absolute neutrophil count.


Inheritance: autosomal dominant (associated with a mutation at the elastase gene ELA2 on chromosome 19)


Onset is typically during infancy but the patient may present as an adult.


Diagnostic features:

(1) cyclic drop in absolute neutrophil count (usually every 21 days, range 14 to 35 days)

(2) minimum absolute neutrophil count <= 200 per µL during an episode (some may use <= 300 per µL)

(3) concurrent bacterial infections during an episode, resulting in periodic fevers (often gingivitis or mucosal infections)


Additional features:

(1) The condition tends to become less severe as the patient gets older.

(2) Most patients have a period of 3-5 days while the absolute neutrophil count is at a minimum.

(3) Aphthous ulcerations may occur.


False negative:

(1) failure to monitor absolute neutrophil count frequently enough to detect a transient drop in the count (recommended testing is 3 times a week for at least 8 weeks, depending on cycle duration)


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