Master the board step 3

Master the Boards: USMLE Step 3
Treatment
Localized disease (Stages I and II) without “B” symptoms is treated predominantly
with radiation and lower-dose chemotherapy. More advanced stage
disease (Stages III and IV) is treated exclusively with chemotherapy:
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HD: ABVD (Adriamycin [doxorubicin], bleomycin, vinblastine, dacarbazine)
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NHL: CHOP (cyclophosphamide, hydroxyadriamycin, Oncovin [vincristine],
prednisone). Also, test for anti-CD20 antigen; if present, add rituximab,
which adds efficacy to CHOP.
Coagulation Disorders
Von Willebrand’s Disease (VWD)
VWD presents with bleeding from platelet dysfunction—superficial bleeding
from the skin and mucosal surfaces, such as the gingiva, gums, and vagina.
Epistaxis is consistent with platelet dysfunction. The question may say the bleeding
is worse with the use of aspirin. The platelet count is normal in VWD.
A case of VWD is likely to
present with epistaxis and/
or petechiae.
The aPTT can be elevated in up to 50 percent of patients with VWD, because
VWF deficiency destabilizes factor VIII.
Diagnostic Testing
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Most accurate tests: Ristocetin cofactor assay and von Willebrand’s factor
(VWF) level. VWF carries factor VIII in the blood.
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If the level of VWF is normal, ristocetin testing will tell if it is working
properly.
Treatment
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First-line treatment: Desmopressin or DDAVP. This will release subendothelial
stores of VWF and factor VIII, which will stop the bleeding.
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If DDAVP is not effective, the next best step in management is to use factor
VIII replacement. Factor VIII replacement has both VWF and factor VIII.
Basic Science Correlate
Mechanism of Ristocetin Testing
Ristocetin acts as an artificial endothelial lining. If VWF is present, platelets
will stick to it. Ristocetin is a functional test of VWF activity.
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