Idiopathic Dysplasia of Unknown Significance (IDUS) is one of the conditions that can give rise to an unexplained hematologic disorder in an older adult. It is associated with risk for progression.

Features of IDUS:

(1) older adult (typically >= 65 years of age)

(2) cytopenias are absent

(3) dysplasia in hematopoietic cells is present in one or more lineages

(4) clonal or molecular aberration: absent

(5) cytogenetic abnormalities: variable

(6) bone marrow blasts less than 5%

(6) not explained by other hematologic or non-hematologic disorder


Dysplastic features that can be seen in the peripheral blood smear may include:

(1) pseudo-Pelger-Huet anomaly

(2) increased band forms

(3) hypogranulated neutrophils

(4) unexplained macrocytosis

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