Axillary lymphadenopathy; This is a spontaneous report from a contactable nurse (parent). A 12-year-old female patient received BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE; solution for injection; lot number: EWD189), via an unspecified route of administration, administered in the right arm on 26Jun2021 (at the age of 12-years-old) as dose 2, single for COVID-19 immunization. The patient has no relevant medical history and no concomitant medications. The patient previously received BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE; lot number: EWD186) administered in the right arm on 05Jun2021 for COVID-19 immunization. On 03Jul2021, the parent noticed that the patient had swelling under the right underarm area, which was the same arm the vaccine was administered in. It was protruding and it was very noticeable from her underarms. It was a soft mass and it felt like it was fluid filled but it was tender and then it also protruded like it was pushing out a little bit. Even with her arm down you can see it. They did do a follow up visit with the pediatrician on 07Jul2021, and the patient was diagnosed with axillary lymphadenopathy. Chest x-ray and blood work were performed, and everything was fine. The pediatrician recommended for the patient to reduce her sodium intake and sitting up as much as she can and then it appeared to dissipate or go down. But then on 15Aug2021, the parent noticed that it was starting to enlarge again, and the patient was reporting tenderness. The parent did not take the patient back to the pediatrician and has been trying to monitor it, but she would like some feedback. The parent knows that this has occurred before but she just wants some feedback from Pfizer. She was told from the CDC and the pediatrician to see if Pfizer has any feedback on what they should be doing. She says this time it looks the same as the original time when they saw it the first time. It looks the same but it did go down. They were following the follow-up visit with the provider and then this week it enlarged again and looks the same as the initial time her daughter had it. The parent stated that it doesn't appear to be life-threatening. It was concerning but they have no regrets with the patient being vaccinated but it was concerning cosmetically for a pre-teen and then just what else could be going on. It was only medically significant. The parent mentioned that the patient has been healthy, and she can barely count on one hand the amount of times that the patient has had any colds that require antibiotics. The patient has been seen annually, she is healthy. She has been underweight, but because of COVID and being home she has gained a little, but she was still being healthy but basically she has been at a normal weight her entire life. The outcome of the event was not recovered.; Sender's Comments: Based on the current available information and the plausible drug-event temporal association, a possible contributory role of the suspect product BNT162B2 to the events lymphadenopathy cannot be excluded   The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to regulatory authorities, Ethics Committees, and Investigators, as appropriate