Idiopathic cytopenia of undetermined (or uncertain) significance (ICUS) was defined by a working conference of hematologists from around the world. The term was proposed by Dr. G. Mufti in 2005 at the 8th International Symposium on MDS.



(1) cytopenia of 1 or more lineages for >= 6 months

(1a) hemoglobin < 11 g/dL

(1b) absolute neutrophil count < 1,500 per µL

(1c) platelet count < 100,000 per µL

(2) absence of known cause after an extensive workup, including myelodysplastic syndrome


The suggested workup includes:

(1) a complete history including occupational, chemical and infectious exposures

(2) a complete listing of all medications

(3) a complete physical examination with assessment of splenic size

(4) peripheral blood smear examination

(5) bone marrow examination

(6) an evaluation for HCV, HIV, CMV, EBV and other viral pathogens

(7) chromosome analysis with FISH

(8) flow cytometry on peripheral blood and bone marrow

(9) additional molecular studies as indicated


The patient should be followed at regular intervals to see if the condition progresses, persists or resolves.


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