Haematology question - Help.

[Phloston]

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This isn't even a matter of debating the actual answer for this particular question as much as it is a recognition of an apparent disagreement between Kaplan QBook and First Aid.

The question from p.242 of Kaplan QBook, 5th edition:

A 13-year-old boy presents to the ED with a deep skin abrasion on his knee. He states that it has not stopped bleeding since it happened during recess approximately 20-30 minutes ago. Physical examination reveals a well-developed, well-nourished adolescent. There are multiple purport over his legs and arms and a few scattered petechiae on his chest and gums. His bleeding time = 22 minutes, platelets = 300,000/mm^3 and haemoglobin = 11 g/dL. A trial of cryoprecipitate transfusion does not improve his bleeding time, but a normal platelet transfusion does. Which of the following is the correct diagnosis?

A) Bernard-Soulier syndrome (should be disease, but Kaplan says syndrome)
B) Henoch-Schonlein purpura
C) Idiopathic thrombocytopenic purpura
D) Thrombotic thrombocytopenic purpura
E) Von Willebrand disease

Kaplan says the answer is A.

Not only is this guy's platelet count normal, but in the explanation, it says "Bernard-Soulier syndrome is an autosomal recessive disease of platelet adhesion that causes prolonged bleeding times in the presence of normal platelet counts."

P. 387 of FA has a down arrow for platelet count for Bernard-Soulier disease. In fact, one of the biggest ways to differentiate BSD from Glanzmann's thrombasthenia is based on the latter demonstrating a normal PC, whereas the former yields a P paucity.

The other answers are evidently not correct, but I'm just left uncertain as to what platelet count should be for BSD (i.e. down or normal, or possibly either).

When I read this question, before even looking at the answer choices, I thought it was Glanzmann's.

Any thoughts here?

Cheers,


Just found a good article on PubMed:

Arch Pathol Lab Med. 2007 Dec;131(12):1834-6.
Bernard-Soulier syndrome: an inherited platelet disorder.
Pham A, Wang J.

Abstract says: Bernard-Soulier syndrome is an inherited platelet disorder, which is transmitted in an autosomal recessive manner. This syndrome is characterized by variable thrombocytopenia and large defective platelets...

 

[lemonade90]

I think if you administered the platelets the disorder would correct because 1b binds to the wvF/collagen at the site of injury. If you give normal platelets, they would have normal 1b and so would be able to bind as there isn't a problem with the wvF/collagen.

As for the platelet count, its the first time I have heard they are normal in BS. I have always read/learned that it was down.

 

[tjquinn]

The arrow on p. 387 may be overstating the truth. It is most definitely not an absolute reduction in platelets for Bernard-Soulier (it is mild decrease, if even that). However, of all of the answer choices, A is the right one. It doesn't matter that this scenario may fit Glanzmann's better (this reminds of Dr. Goljan discussing what would increase surfactant production in a baby born at 32 weeks, everyone was looking for steroids of some sort, but that choice wasn't there... so, some people "wrote in steroids" as an answer choice).

Now, if Glanzmann's and Bernard-Soulier were both answer choices, then the above information would lead to you pick Glanzmann's. Alternatively, if they still wanted you to pick Bernard-Soulier, then they would mentioned a peripheral smear demonstrating oversized platelets (Bernard-Soulier - Big Suckers), which is another characteristic. The platelet count may be decreased in Bernard-Soulier (due to an overall decrease in lifespan of platelets, or inefficient thrombopoeisis), but that absence of a low platelet count does not seem to be enough to exclude it as an answer choice and choose any of the others.

 

[Phloston]

I think if you administered the platelets the disorder would correct because 1b binds to the wvF/collagen at the site of injury. If you give normal platelets, they would have normal 1b and so would be able to bind as there isn't a problem with the wvF/collagen.

As for the platelet count, its the first time I have heard they are normal in BS. I have always read/learned that it was down.

Good call.

 

[Phloston]

Just searched PubMed, and apparently the thrombocytopenia for BSD is variable. I've posted the article above (one of many).

 

[TooMuchResearch]

I think B-S disease/syndrome has a mild thrombocytopenia, but as we were often taught, "The patients/diseases don't always read the textbooks," so without the low platelet count, if Glanzmann isn't a listed choice, Bernard-Soulier is the best answer by far.

Lemonade is correct on the correction with normal platelets.

 

[Phloston]

The arrow on p. 387 may be overstating the truth. It is most definitely not an absolute reduction in platelets for Bernard-Soulier (it is mild decrease, if even that). However, of all of the answer choices, A is the right one. It doesn't matter that this scenario may fit Glanzmann's better (this reminds of Dr. Goljan discussing what would increase surfactant production in a baby born at 32 weeks, everyone was looking for steroids of some sort, but that choice wasn't there... so, some people "wrote in steroids" as an answer choice).

Now, if Glanzmann's and Bernard-Soulier were both answer choices, then the above information would lead to you pick Glanzmann's. Alternatively, if they still wanted you to pick Bernard-Soulier, then they would mentioned a peripheral smear demonstrating oversized platelets (Bernard-Soulier - Big Suckers), which is another characteristic. The platelet count may be decreased in Bernard-Soulier (due to an overall decrease in lifespan of platelets, or inefficient thrombopoeisis), but that absence of a low platelet count does not seem to be enough to exclude it as an answer choice and choose any of the others.

I had always had the impression that GT and BSD were also differentiated based on PC in addition to size and clumping. Perhaps it's therefore safe to say that the down arrow for BSD in FA should be changed to "down or -."

 

[tjquinn]

I had always had the impression that GT and BSD were also differentiated based on PC in addition to size and clumping. Perhaps it's therefore safe to say that the down arrow for BSD in FA should be changed to "down or -."

Yeah, I have noticed that FA sometimes (well often) makes pretty bold statements about things that can be quite variable or depend on the patient and their current progression in the disease, but I guess they do that to avoid the neutral stance and as a way to not have to add qualifying statements to the summary tables.