Summary
Venous thrombosis typically involves the lower extremity circulation. Rarely, it can
occur in the cerebral or splanchnic veins and these are the most frightening manifestations
because of their high mortality rate. A third site of rare venous thrombosis is the
deep system of the upper extremities that, as for the lower extremity, can be complicated
by pulmonary embolism and post-thrombotic syndrome. The authors conducted a narrative
review focused on clinical manifestations, risk factors, and treatment of rare venous
thromboses. Local risk factors such as infections or cancer are frequent in thrombosis
of cerebral or portal veins. Upper extremity deep-vein thrombosis is mostly due to
local risk factors (catheter- or effort-related). Common systemic risk factors for
rare venous thromboses are inherited thrombophilia and oral contraceptive use; chronic
myeloproliferative neoplasms are closely associated with splanchnic vein thrombosis.
In the acute phase rare venous thromboses should be treated conventionally with low-molecular-weight
heparin. Use of local or systemic fibrinolysis should be considered in the case of
clinical deterioration in spite of adequate anticoagulation. Anticoagulation with
vitamin K-antagonists is recommended for 3–6 months after a first episode of rare
venous thrombosis. Indefinite anticoagulation is recommended for Budd-Chiari syndrome,
recurrent thrombosis or unprovoked thrombosis and permanent risk factors. In conclusion,
the progresses made in the last couple of decades in diagnostic imaging and the broadened
knowledge of thrombophilic abnormalities improved the recognition of rare venous thromboses
and the understanding of pathogenic mechanisms. However, the recommendations for treatment
mainly derive from observational studies.
Keywords Cerebral vein thrombosis - Budd-Chiari syndrome - extrahepatic portal vein thrombosis
- mesenteric vein thrombosis - upper-extremity deep venous thrombosis