PTGS2 and fibrodysplasia ossificans progressiva: Cyclooxygenase-2 inhibitors are used after steroid is stopped or when it is used to manage the symptoms.10 It is not advisable to use steroid for minor flares or flares involving the back or trunk as these are usually longer duration and are recurring in nature.27 Mast cells are seen frequently in the pre-osseous phase of soft tissue swelling and its depletion showed improvement in HO lesions in a mouse model of FOP.30 Imatinib which is a C-kit inhibitor, causes mast cell apoptosis and depletion.