a lump/has a lump under her arm; she noticed where her thighs join her torso or crotch area was tender on the right side as well, with a tiny bit to the left; swelling under her right arm; This is a spontaneous report received from a contactable reporter(s) (Consumer or other non HCP) from medical information team. The reporter is the patient.  A 64 year-old female patient received bnt162b2 (BNT162B2), administered in arm left, administration date 12Oct2021 (Lot number: FF2590, Expiration Date: 13Nov2021) at the age of 64 years as dose 3 (booster), single for covid-19 immunisation. The patient's relevant medical history was not reported. There were no concomitant medications. Vaccination history included: Bnt162b2 (Dose 1, LOT: EN6206 , Expiry date 30Jun2021), administration date: 15Mar2021, when the patient was 63 years old, for Covid-19 Immunization; Bnt162b2 (Dose 2, NDC was not provided for this dose, EXP: 31Jul2021 , LOT: ER8733), administration date: 08Apr2021, when the patient was 64 years old, for COVID-19 immunization. The following information was reported: SWELLING (non-serious) with onset 2021, outcome "unknown", described as "swelling under her right arm"; AXILLARY MASS (non-serious), outcome "unknown", described as "a lump/has a lump under her arm"; TENDERNESS (non-serious), outcome "unknown", described as "she noticed where her thighs join her torso or crotch area was tender on the right side as well, with a tiny bit to the left". Therapeutic measures were not taken as a result of swelling, axillary mass, tenderness.  Additional information: It was reported that Caller is a 64-year-old female who received the primary vaccination series and the booster dose of the Pfizer COVID-19 vaccine. She received the booster dose on 12Oct2021. She received all three doses in her left arm. However she developed swelling under her right arm with a lump for almost three weeks. Caller wants to know if this is a common side effect reported with Pfizer COVID-19 vaccine. She also wants to know how long the side effects last. She noticed where her thighs join her torso or crotch area was tender on the right side as well, with a tiny bit to the left. Consumer says she was wondering because she had Pfizer COVID-19 vaccine, two doses and a booster, and she seems to be having swelling under one of her arms. She says she noticed that lymph node swelling is listed as a possible side effect on the vaccine fact sheet, so she was wondering if this could be one of the side effects. Caller says the under arm swelling started just about 3 weeks ago, and it has stabilized, she has a lump under her arm that after about a week reached the size it is now. She says it stabilized and is still there, and has been about three weeks. She says it was a bit uncomfortable, but not painful, it is under her right arm. She says when it first started she noticed where her thighs join her torso or crotch area was tender on the right side as well, with a tiny bit to the left, but she can't say she wasn't just projecting, though it was surely on the right side then went away. AE Treatment: Queried, caller said no, started to say something and then changed her mind and didn't finish what she was saying. Follow-up attempts are completed. No further information is expected.  No follow-up attempts are possible. No further information is expected.