Abstract Number: PB0989
Meeting: ISTH 2022 Congress
Background: Factor V is synthesized in the liver and is a cofactor to the prothrombinase complex that converts prothrombin to thrombin. Inhibitor formation against factor V is rare and has been associated with infections, antibiotics, surgery, malignancy, and autoimmune disorders. Factor V inhibitor has a wide range of clinical manifestations: from being asymptomatic to major bleeding.
Aims: To describe a case of an acquired factor V inhibitor associated with metastatic cancer.
Methods: Retrospective case review.
Results: This case involves an 85-year-old gentleman with distant history of right ileocolic stage II colon cancer, h/o of atrial fibrillation on apixaban, and TURBT for a high-grade noninvasive papillary urothelial carcinoma followed by intravesical BCG. He underwent a TAVR complicated by incision site infection treated with cephalosporins. The pre-procedure lab work revealed normal PT and aPTT. Following the TAVR, the patient had gradually increasing pelvic and pulmonary nodules with rising CEA concerning for metastatic disease. A biopsy was planned and pre-biopsy laboratory testing revealed a remarkably elevated PT. Clinically, the patient exhibited signs of minor bleeding (epistaxis and bruising). Apixaban was discontinued once lab work revealed elevated PT and mixing studies showed lack of correction consistent with immediate acting inhibitor. Other labs include Factor V assay < 1% and Factor V Inhibitor of 4.1 Bethesda units. Due to the risk of bleeding and the patient’s preference to not consider any systemic chemotherapy, the planned biopsy was abandoned. The factor V inhibitor was likely related to metastatic disease. The patient was treated with Rituximab and subsequently IVIG resulting in a stepwise increase of factor V levels and simultaneous drop in factor V inhibitor.
Conclusion(s): Acquired factor V inhibitor can be associated with metastatic cancer and in the absence of being able to treat the underlying cause such as cancer, it can be treated with rituximab and IVIG.
To cite this abstract in AMA style:Dhami D, Changizzadeh P, Solowiej Singh C, Dhami S, Muttana S. Acquired Factor V Inhibitor In a Patient With Metastatic Cancer [abstract]. https://abstracts.isth.org/abstract/acquired-factor-v-inhibitor-in-a-patient-with-metastatic-cancer/. Accessed September 26, 2022.
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