If a patient with myeloma develops a symptomatic DVT or PE while on an immunomodulatory drug such as lenalidomide, would you stop the IMiD?   

In general I prefer using enoxaparin (most convenient LMWH in US) or apixaban (least renally dependent Xa inhibitor) in myeloma patients for IMiD-induced VTEs.  I don't generally wait 7-10 days as the anticoagulant effect is rapid for these agents.   While compliance is always challenging...