Myeloperoxidase is a lysosomal hemoprotein that is stored in the cytoplasmic azurophilic granules of neutrophils. Deficiency of myeloperoxidase may predispose the patient to disseminated fungal infections if certain conditions are present.


Conditions associated with deficient myeloperoxidase:

(1) hereditary deficiency (autosomal recessive trait with variable expression; deficiency may be partial or complete)

(2) acquired deficiency in myelodysplasia, CML or AML (M2, M3, M4)

(3) acquired deficiency in other conditions


Clinical findings:

(1) Usually the condition is asymptomatic.

(2) The patient may develop disseminated candidemia or other fungal infections if the patient:

(2a) has poorly controlled diabetes mellitus

(2b) becomes immunosuppressed

(3) The patient may be subject to recurrent bacterial or fungal infections if deficiency combined with other defects in neutrophil function.


Laboratory findings:

(1) The condition may be detected on a automated hematology analyzer that measures myeloperoxidase activity.

(2) Affected neutrophils show an absence of cytoplasmic azurophilic granules in the peripheral blood smear.

(3) Cytochemical stains for peroxidase are negative or shows markedly reduced staining.


Management includes:

(1) aggressive management if a fungal infection develops

(2) tight control of blood sugar if diabetic

(3) increased monitoring if immunosuppressed


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