Pericarditis/myocarditis; Pericarditis/myocarditis;   This is a non-interventional study report received from a contactable reporter (Physician).  A 36-year-old female patient received BNT162b2 (Pfizer Covid-19 vaccine), as dose 3, single (Batch/Lot number: unknown) intramuscular for covid-19 immunization. The patient's relevant medical history included: "Adult-onset Still's disease" (ongoing); "Macrophage activation syndrome" (ongoing); "Pneumonia", start date: 06Sep2021 (unspecified if ongoing). The patent took the following concomitant medications: Salbutamol (ALBUTEROL) 90mcg inhaled, for shortness of breath,  Anakinra for immune suppression, calcium 600 mg/vitamin D 400 units, cetirizine, clobetasol 0.05% ointment, dextran 70/glycerol 0.02%/hypromel 0.3%, diclofenac 1% topical gel for pain, dextromethorphan (DM)10/guaifenesin 100mg/5ml, for cough, fluticasone for allergy symptom, omeprazole, prednisone, tocilizumab 162mg autoinjector, carboxymethylcellulose 1% opth gel apply 1 drop to both eyes, three times per day, acetaminophen 500mg by mouth every 8 hours, biotin, doxepin, fish oil, and levonorgestrel; all ongoing (reported active medicines). The following information was reported: Pericarditis/myocarditis" (hospitalization) with onset 05Sep2021. "Clinical course: The patient with Adult-Onset Still's Disease (AOSD), Macrophage Activation Syndrome, who presented to the hospital with shortness of breath and fevers 1 week after being given her 3rd dose of Pfizer's COVID-19 vaccine. The patient was diagnosed with pneumonia as well as concomitant myopericarditis. She was noted to have elevated cardiac biomarkers which then resolved over time with treatment of both the pneumonia and the myopericarditis. The patient recovered from the event without significant adverse sequelae. In follow-up, in the outpatient setting, her Rheumatologist's opinion was that the episode occurred as a result of the third dose of vaccine. The reporter became aware of this case while reviewing charts for patients as part of a project looking at the association between the Pfizer Covid-19 vaccine and incidence of pericarditis/myocarditis. In the reporter's opinion, the possible causes for the episode included pericarditis associated with the patient's episode of pneumonia, a flare of AOSD or exposure to the vaccine (due to the close temporal relationship). The patient was seen at the hospital on Sep2021 and it was unknow if an adverse reaction was reported to Pfizer for this patient at the time of the event as the reporter reviewed the events, it occurred less than 8 months after the illness occurred. The patient underwent the following laboratory tests and procedures: Troponin (0.0-0.3): (06Sep2021) 4.86 ng/ml; (07Sep2021) 4.94 ng/ml; (19Oct2021) less than 0.02 ng/ml. The action taken in response to the event was not applicable (not reported). Outcome of the event was recovered on unspecified date.  The reporter considered "pericarditis/myocarditis" related to third dose of BNT162b2, but not related to concomitant medications.; Sender's Comments: Based on known drug safety profile, there is reasonable possibility of causal association between the events pericarditis and myocarditis and BNT162B2.