Here is the second of three installments of a really nice quiz one of our readers sent (the first installment is here , and the third one is coming up). This is a quiz he recently gave to his residents (from medicine, pediatrics and pathology) rotating through hematopathology. Give it a try and see how many you get right! Make sure you check out the answers and nice explanations (if I do say so myself) at the end.
1. Smudge cells may be seen on the peripheral blood smear in which of the following?
2. The erythroblasts in acute erythroleukemia (AML- M6) are usually positive for which of the following?
D. All of the above
3. The rare Bombay phenotype is seen in people who have blood type :
4. Cryoprecipitate contains which of the following factors?
A. Factor VIII
B. Factor IX
C. Factor II
D. Factor VII
5. The major hematopoietic site in the human embryo is:
D. Yolk sac
6. POEMS syndrome includes all of the following EXCEPT:
D. Skin abnormalities
7. The most common class of immunoglobulin produced by the malignant cells in multiple myeloma is:
8. Which of the following is true with respect to hemophilia A ?
A. Inheritance is autosomal dominant
B. It is more common in females
C. It never manifests before puberty
D. Patients are deficient in factor VIII
9. The cells of which of the following have a “fried-egg” appearance on bone marrow sections?
A. Hairy cell leukemia
B. Follicular lymphoma
C. Acute promyelocytic leukemia
D. Burkitt’s lymphoma
10. Which of the following immunophenotypic markers is a pan-B-cell marker?
Scroll down for the answers…
1. A. Smudge cells (also called ghost cells or basket cells) are actually damaged lymphocytes rather than a unique type of cell. Lymphocytes are more fragile than myeloid cells (like neutrophils) – so when you make a blood smear in a patient with a lymphoid disorder (like chronic lymphocytic leukemia), there are likely to be a bunch of smudge cells.
2. D. CD71 and CD117 are both erythroid markers. Erythroblasts in AML-M6 will often stain positively with the PAS (periodic acid schiff) stain (which stains glycogen and mucopolysaccharides). Normal erythroblasts are generally not PAS positive though.
3. A. People with the Bombay phenotype don’t make H antigen. What’s H antigen, you say? It is the antigen that you make first, before you create A or B antigens. To make A and B antigens, you start with a protein precursor (sticking out of the red cell membrane). You add fucose to make what’s called the H antigen. Then, if you have the A gene, you add N-acetylgalactosamine to the H antigen, which makes it an A antigen. If you have the B gene, you add galactose to the H antigen, which makes it a B antigen. If you don’t have either A or B (in other words, if you are type O), then you just leave the H antigen as is, and you don’t make either A or B antigens.
So…people with the Bombay phenotype do not make the H antigen (they stop at the protein precursor stage). They therefore don’t make A or B antigens, either (so they are type O). If a person with the Bombay phenotype needs a transfusion, you need to find Bombay blood – because if you give any other type (regular A, B, AB or O), that blood will have some H antigen in it, and the patient will bust open all those donor red cells (not a good thing to have happen!).
4. A. Cryoprecipitate is a plasma product that contains fibrinogen, von Willebrand factor, and factors VIII and XIII.
5. D. Ok, kind of a gimme.
6. B. POEMS is a rare syndrome that includes a plasma cell dyscrasia (usually myeloma) and a bunch of other stuff. The acronym covers some of the main features: polyneuropathy, organomegaly, endocrinopathy or edema, M-protein, and skin abnormalities (including hyperpigmentation and hypertrichosis). There are other potential complications, though – and not every patient with POEMS has all five features.
7. C. The most common class is IgG. The rarest is IgM. Some people argue that an IgM myeloma doesn’t exist; others say that it exists but is super super rare. Either way, if you get a plasma cell thing that expresses IgM, the first thing you should think of is Waldenstrom’s – myeloma would be way, way down on the list.
8. D. In hemophilia A, patients are deficient in factor VIII (in hemophilia B, it’s factor IX that is deficient). Inheritance is X-linked recessive (though up to 30% of cases arise spontaneously!). As any X-linked recessive disorder, it is more common in males. It often manifests in childhood.
9. A. The hairy cells in hairy cell leukemia have been described as having a “fried egg” appearance because they have these long cytoplasmic processes (“hairs”) that push the cells apart from each other. So the little cell nuclei look like the yolks of eggs, with egg whites (cytoplasm) around them.
10. B. CD19 is a marker present on most B cells (so it’s a “pan” B-cell marker). CD3 is a T-cell marker; CD33 is a myeloid cell marker, and CD56 is a natural killer cell marker.