1/10

Case
76 Yo M With...

Metadata

• Author: @WilliamAird4 on Twitter
• Full Title: 1/10
  Case
  76 Yo M With...
• Category: #tweets
• URL: https://twitter.com/WilliamAird4/status/1634181115098324992

Highlights

• 1/10
  CASE
  76 yo M with Waldenstrom's macroglobulinemia (WM; IgM 3000-5000 mg/dL), treated in past with rituximab, dexamethasone and cytoxan, presents with iron deficiency anemia. Colonoscopy and OGD negative. Capsule study shows multiple jejunal AVMs.
  Ring any bells?
  (View Tweet)
• 2/10
  OK, a hint:
  PT 11.5
  aPTT 48.7
  (aPTT 2 years ago was normal)
  2 approaches:
  1. Type 1 thinking - SPOT diagnosis (no conscious thought involved)
  2. Type 2 thinking - what is the ddx of an elevated aPTT and which if any cause fits with the patient's presentation?
     (View Tweet)
• 3/10
  Differential diagnosis of elevated aPTT:
  Since the aPTT measures the integrity of the intrinsic pathway, the ddx includes deficiency of, or inhibitor against one or more components of the intrinsic pathway, including FXII, FXI, FIX, and FVIII.
  (View Tweet)
• 4/10
  Since the aPTT in the past was normal, we are dealing with an acquired condition. Highest on the list:
  1. FVIII inhibitor associated with (a/w) WM
  2. avWD a/w WM
  3. Lupus anticoagulant (incidental)
     ... wait, why is vWD on the list - it's not part of the clotting cascade. (View Tweet)
• 5/10
  Because vWF carries and protects FVIII from clearance. Low vWF --> low FVIII --> elevated aPTT
  The results for FVIII and vWD are shown in the graphic - the data are most consistent with acquired vWD.
  What about the GI bleeding? Is there a connection with the WM/avWD?
  (View Tweet)
• 6/10
  YES!!
  Acquired vWD is associated with the formation of AVMs in the GI tract (probably related to loss of vWF-mediated suppression of VEGF activity). (View Tweet)
• 7/10
  avWD - DEFINITION
  avWD is a rare bleeding disorder caused by reduced levels and/or function of vWF that is not directly inherited but typically as a consequence of other medical disorders. (View Tweet)
• 8/10
  avWD - CAUSES
  1. Lymphoproliferative disorders (like our patient)
  2. Plasma cell dyscrasias
  3. MPN
  4. Cardiac conditions
  5. Autoimmune disorder
  6. Hypothyroidism (View Tweet)
• 9/10
  avWD - MECHANISMS
  1. Immune (antibody clearance or inhibition of vWF - like in our patient)
  2. Shear-stress induced proteolysis
  3. Absorption of vWF to cells
  4. Decreased vWF synthesis (View Tweet)
• 10/10
  avWD - TREATMENT
  1. Hemostatic (e.g. vWF concentrates) for bleeding
  2. Treatment of underlying disease
     For infographic on avWD see:
     https://t.co/NfaO8lageJ (View Tweet)