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Blood, 1 April 2003, Vol. 101, No. 7, pp. 2453-2453
EDITORIAL
A (blood) smear campaign
A 40-year-old patient (who insists on being called
Pete) is referred to you for evaluation of asymptomatic
thrombocytopenia discovered during preoperative blood testing for an
elective cholecystectomy. Except for cholelithiasis, he has no
significant medical history and no prior surgeries other than
uneventful extractions of molar teeth. The referring physician is
concerned about the platelet count of 50 000/µL and the fact that
"large platelets" were reported from the laboratory. He queries
whether a bone marrow examination is indicated for diagnostic purposes,
whether corticosteroids should be administered for presumptive
idiopathic thrombocytopenic purpura, and whether consideration should
be given to changing the operative plan and performing a combined
cholecystectomy and splenectomy. After conducting a history and physical examination, which reveal no
additional abnormalities, you examine the patient's peripheral blood
smear. You find that almost all of the platelets are very large, some
even larger than red blood cells, and many of the granulocytes contain
cytoplasmic Döhle body-like inclusions. You
unhesitatingly make the diagnosis of May-Hegglin anomaly, a form of
inherited thrombocytopenia due to mutations in nonmuscle myosin
heavy chain A.1 Then you clear the patient for
cholecystectomy, with recommendations to avoid aspirin and to have
platelet concentrates and autologous red blood cells available in the
unlikely event that they are needed. The surgical procedure is
undertaken without complications or the need for transfusions.
Subsequent evaluation finds that Pete is not the only member of his
family with asymptomatic macrothrombocytopenia: a sister and a
son are similarly affected. This case, although fictional, illustrates the value of examining the
peripheral blood smear in patients referred for hematologic consultation. The conventional Wright-Giemsa-stained blood smear is to
the hematologist what urine sediments are to the nephrologist or
eyegrounds are to the ophthalmologist: windows to the inner workings of
the body in health and disease. And it is arguably more pleasing to
look at! As Jandl put it in 1987 and it is still true, "more
information can be gained from examining the blood smear than from any
other single hematologic procedure." 2(p33)
While I know that all experienced clinical hematologists would agree with this sentiment, over the years I have occasionally seen
diagnoses missed and therapeutic plans misguided by the failure of
physicians responsible for patient care to personally review blood smears, especially when the workup suggests that there is a
hematologic problem. In this country, abnormalities in the peripheral blood smear are
frequently discovered by the clinical hematology laboratory, and they
are then vetted by a hematopathologist, who transmits this information
to the clinician. However, this sequence of events, although
appropriate, is no substitute for a careful review of the blood smear
by the patient's physician, whose responsibility it is to synthesize
information from the entire clinical and laboratory data base. Since
routine analysis of blood smears is a learned behavior and correct
interpretation is facilitated by experience, we owe it to the younger
generation of physicians, especially hematology trainees, to pass on
this skill. More pragmatically, proficiency in blood smear analysis is
a procedural requirement for certification in Hematology-Oncology by
the American Boards of Internal Medicine and Pediatrics. Given the importance of peripheral blood smears in hematology practice,
Blood has begun publishing illustrative blood smears and
occasional bone marrows, accompanied by short explanatory text. This
new series is called "Blood Work" (see page 2452 in this issue).
The goal is to highlight some of the diagnostic clues and raw beauty
inherent in blood smears, with an attempt to educate and perhaps even
to titillate, but not to be encyclopedic. Digital photomicrographs are
drawn from the Image Bank of the American Society of Hematology, whose
editorial board members have graciously helped to select images and
permit their use. Readers interested in accessing or contributing
high-quality images to the Image Bank are referred to
www.ashimagebank.org. So, trainees, temporarily eschew the microarray and microchip for the
microscope. Make it a practice to review blood smears, to become
proficient in their interpretation, and to record the results in the
patient record, for Pete's sake!
Sanford J. Shattil, MD
Editor-in-Chief
References
1.
Kunishima S, Kojima T, Matsushita T, et al.
Mutations in the NMMHC-A gene cause autosomal dominant macrothrombocytopenia with leukocyte inclusions (May-Hegglin anomaly/Sebastian syndrome).
Blood.
2001;97:1147-1149[Abstract/Free Full Text].
2.
Jandl JH.
Blood: Textbook of Hematology. 1st ed. Boston: Little, Brown and Company; 1987.
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