Primary immune thrombocytopenic purpura (ITP)

(Blood 2010;115:168)

• Isolated thrombocytopenia due to immune plt destruction (auto-Ab to plts) & ↓ production (auto-Ab to megakaryocytes) without precipitant

• Clinical manifestations: insidious onset of mucocutaneous bleeding; ♀:♂ = 3:1

Diagnosis of exclusion

(r/o 2° ITP); no robust clinical or lab parameters, but typically:

• CBC: isolated ↓ plt (<100,000/µL); 10% have ITP + AIHA = Evans syndrome
• Peripheral smear: large platelets (not specific), r/o pseudothrombocytopenia
• BM bx: ↑ megakaryocytes, nl cellularity. Consider if other CBC or smear abnl or diagnostic uncertainty (Blood 2011;117:4910).
• ✓ HBSAg & anti-HBc prior to rituximab (and before IVIg, which could alter results)

Treatment

• rarely indicated if plt >50,000/µL unless bleeding, trauma/surgery, anticoag.
• Treatment of Primary ITP in Adults

Post-splenectomy vaccinations needed. (Blood Adv 2019;3:3829; Eur J Haem 2018;100:304)