[Polycythemia vera with an inhibitor against factor XII]

Area of Science:

• Hematology
• Oncology
• Immunology

Background:

• Polycythemia vera is a myeloproliferative neoplasm characterized by erythrocytosis.
• Acquired inhibitors of coagulation factors are rare but can cause significant bleeding or thrombotic complications.

Observation:

• A 60-year-old female presented with erythrocytosis and hepatosplenomegaly, diagnosed with polycythemia vera.
• Initial laboratory findings revealed decreased factor XII activity without a history of bleeding.
• Plasma analysis confirmed the presence of an inhibitor against factor XII, identified within the IgG fraction.

Findings:

• The patient was diagnosed with polycythemia vera based on established criteria.
• An acquired inhibitor targeting factor XII was identified in the patient's plasma.
• Treatment with phlebotomy, PLAC (a cytosine arabinoside derivative), and Busulfan led to gradual correction of factor XII activity.

Implications:

• This case highlights a rare association between polycythemia vera and an acquired factor XII inhibitor.
• The findings suggest that certain treatments for polycythemia vera may influence coagulation factor activity.
• Further research is warranted to understand the mechanisms underlying this association and its clinical significance.