Henoch-Schonlein Purpura with thrombocythaemia: an abnormality in Smad4 expression?

We discuss a patient with Henoch-Schonlein Purpura (HSP) and a thrombocythaemia which was diagnosed as a coincidental Essential Thrombocythaemia. We suggest that deficiencies in Smad4 expression may allow for escape thrombocythaemia under the influence of the high levels of TGF-beta found in HSP. With normal Smad4 expression TGF-beta provides inhibition of thrombocyte proliferation. While this needs further elucidation, it could lead to a new approach to classification and management of HSP.