It is interesting that some errors in hematology laboratory can give sign and clue to disease diagnosis: in this review we have gathered some of these common errors.

  For example: lymphocytosis in association with smudged cell can be helpful in diagnosis of chronic lymphocytic leukemia. Smudged cell is a lab artifact that is produced by spreader pressure during smear preparation.

  Extreme false thrombocytosis in presence of microcytic and hypochromic anemia strongly suggest hemoglobin H disease.

  The platelet satellitism that is an in vitro phenomenon, is sometimes accompanied with antiphospholipid syndrome.

  Turbidity of drabkin solution in hemoglobin measurement can lead to suspecious of hemoglobinopathies.