text: Post COVID 19 exacerbation of fibrodysplasia ossificans progressiva with multiple flare ups and extensive heterotopic ossification in a 45 year old female patient Fibrodyplasia ossificans progressiva FOP is a rare hereditary disease which has a variable course characterized by occasional flare ups of heterotopic ossification HO in soft tissues that are followed by swelling stiffness pain and warmth Here we report for the first time a case of a 45 year old female patient with known FOP recovering from COVID 19 with disease progression potentially linked with the viral illness In December 2020 the patient contracted a mild form of COVID 19 infection without need for hospital admission Since January 2021 the patient felt unwell with occasional abdominal pain which progressively intensified In March 2021 she presented with new onset of HO complaining of pain swelling and thickening sensation in the lower abdomen and left part of the neck Computerized tomography CT and cytokine analysis were performed CT scan revealed new heterotopic bone formation in multiple soft tissue areas of the neck indicating clear radiological progression Radiotherapy which has proven to be an efficient tool to control HO in this patient was not able to halt HO formation after COVID 19 infection Cytokine analysis of a plasma sample obtained during a flare up after COVID 19 infection showed a significantly elevated pro inflammatory cytokines compared to a flare up panel prior to infection Of the 23 analyzed levels of cytokines a staggering number of 21 were above normal levels This case is the first confirmation of uncontrolled post COVID 19 effects in a FOP patient which manifested with flare ups followed by progressive HO possibly caused by a thus far never described form of post COVID syndrome 