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Retired NBME 20 Answers

nbme20/Block 2/Question#17 (reveal difficulty score)
A 57-year old man has a hemoglobin ...
Chronic obstructive pulmonary disease ๐Ÿ” / ๐Ÿ“บ / ๐ŸŒณ / ๐Ÿ“–
tags: hemeonc polycythemia

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 +17  upvote downvote
submitted by โˆ—hayayah(1212)
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This is reactive polycythemia vera, which is due to high altitude or lung disease. SaO2 is low, and EPO is increased.

Another way to approach the question is looking at the blood smear. It's pretty normal (no megakaryocytes, no increased number of platelets, no rods, nothing blue, etc). A blood smear from a COPD patient will be normal. Just an increased number of RBCs due to the increased EPO leading to increased Hgb.

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mbourne  You shouldn't call it reactive polycythemia "vera", as polycythemia vera is a seperate disease with entirely different etiology. This is Reactive Polycythemia, or as another poster said, appropriate absolute polycythemia secondary to chronic hypoxia. +24
j44n  i jumped on myelodysplastic thinking it was PV due to the jak w mutation but you technically get elevated everything in that mutation so it would be more than just RBC's +
beetbox  I also thought it was PV. How can we tell reactive polycythemia from actual PV, if PV does not show other kinds of blood cell counts raised but just an isolate of RBC rise? +1
l0ud_minority  I got this wrong but here my rationale Based off the information in the passage how can How can you differentiate this from inappropriate absolute polycythemia? Paraneoplastic syndrome is associated with cancers such as Hepatocellular Carcinoma. Hereditary hemochromatosis can leave to liver cirrhosis. That's why I chose C. But I was wrong. +1
epiglotitties  I'm confused, Polycythemia Vera wasn't in the answer choices, D) was myelodysplastic syndrome which I don't think is the same as myeloproliferative disorders- which include PV, Essential Thrombocythemia and Myelofibrosis-. Or are they the same thing?? Also @beetbox, the way to tell reactive polycythemia from PV is by looking at EPO. In reactive it is elevated and is what is leading to the increase in RBCs, and in PV the increase in RBCs is due to neoplastic transformation of RBC precursos NOT excess EPO. +



 +9  upvote downvote
submitted by โˆ—alexb(53)
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I confused myelodysplastic syndrome with primary myelofibrosis because I thought 2-3 of those RBCs looked like teardrop cells. Just like when they show an image for bullous pemphigoid and there's some weird second rip through the dermal/subdermal layer making me think it's not BP even though I don't know what else it would be. fml

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whoissaad  Made the same mistake +9
targetusmle  i thought exactly the same!! 2 cells looked like tear drop cells :/ +2
ilovemypuppies2295  I thought there were tear drop cells too. Seemed like it should be a metaplasia then. Oh well +
lynn  I did the same, but looking at FA19 pg 423 it says "ineffective hematopoiesis --> defects in cell maturation of nonlymphoid lineage." You can get bilobed neutrophils, or if it progressed to AML you'd see auer rods. Nothing about tear drop cells. Then on pg 406 tear drop cells would be seen in myelofibrosis, and possibly thalassemias +
waterloo  I thought the same, but I think that would be myelofibrosis, not myelodysplastic. Hb is really high here too. Pretty tricky for them to put that there, easy knee jerk. +1
jawnmeechell  Interestingly enough, agnogenic myeloid metaplasia is the old name for myelofibrosis, with "agnogenic" being synonymous with "idiopathic." (or did everyone already know this) +1
bfinard1  Primary myelofibrosis is a myeloproliferative disorder not a myelodysplastic syndrome +



 -6  upvote downvote
submitted by โˆ—strugglebus(189)
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Pt has polycythemia vera (myeloproliferative disorder) due to chronic hypoxia induced by COPD. Myeloid metaplasia is extra medullary hematopoiesis due to myelofibrosis. Hereditary hemochromatosis would have been proven by a prussian blue stain. Hypersplenism would have caused decreased RBCs, and myelodysplasic syndrome would have shown Auer rods or blasts.

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neonem  Right, I think this would be just called "appropriate absolute polycythemia", whereas polycythemia vera is due to a malignant JAK2 mutation and would be termed a type of chronic myeloproliferative disorder. +14
utap2001  Myelodysplastic syndromes (MDS) is also called Preleukemia, myelodysplasia. in MDS, your bone marrow doesn't make enough of these healthy blood cells. Instead, it makes abnormal cells that aren't fully developed (immature). As the condition develops, your bone marrow gets gradually taken over by the immature blood cells, which don't work properly. The condition can develop slowly (indolent) or quickly (aggressive), and in some people it can develop into a type of leukaemia called acute myeloid leukaemia (AML). +



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