Please note that whilst 'InterruptibleRegion' is referenced in UML-2.5.1 and fUML-1.4, there is no metaclass InterruptibleRegion. Visit also InterruptibleActivityRegion.
Although fUML and Magic Model Analyst® (Cameo Simulation Toolkit®) do not support InterruptibleActivityRegion, one can still interrupt a StructuredActivityNode using a basic AcceptEventAction or a AcceptEventAction with a TimeEvent. Simply have a ControlFlow from the "interrupting" AcceptEventAction to an ActivityFinal within the StructuredActivityNode, or a ControlFlow from the "interrupting" AcceptEventAction to outside the StructuredActivityNode.