the right arm is roughly 2" bigger than the left arm around it.; inflamed; Thought it was dry skin. That area is prone to dry skin.; pretty tired; shortness of breath; chest pain; rash/rash around right arm; Redness in right arm at mastectomy site, and warm to touch; Welts; red bumps; Itching; Nauseated; This is a spontaneous report from a contactable consumer (patient). A 53-year-old female patient received the second dose of BNT162B2, via an unspecified route of administration in left deltoid on 19Apr2021 14:30 at single dose for COVID-19 immunisation. Medical history bipolar disorder, breast cancer, and slightly high blood pressure. Patient had a right mastectomy and had lymph nodes removed from the right side. In the spring, when everyone was mowing grass and it was real humid outside, she got welts on her body. It was temporary and went away. Patient would get really itchy. Concomitant medications included letrozole for breast cancer (the tumor in her breast was powered by hormones. This drug suppressed hormones) from 2017 and ongoing, omeprazole for constant heartburn from an unspecified date and ongoing, propranolol hydrochloride (PROPANOLOL) for anxiety from 2016 and ongoing, clonazepam for anxiety from 2016 and ongoing, and venlafaxine hydrochloride (EFFEXOR) for bipolar disorder from an unspecified start date and ongoing. Patient previously received the first dose of BNT162B2 in left deltoid on 29Mar2021 11:30 for COVID-19 immunisation and was really tired after the first vaccine. When she was a kid, her doctor put her on steroids. Never happened after age 12. Patient also got the influenza vaccine (flu shot) a couple of years before. The patient experienced redness in right arm at mastectomy site, and warm to touch, welts, red bumps, itching, and nauseated on 20Apr2021. Patient had a right mastectomy and had lymph nodes removed from the right side. In the area where that occurred, it had become red, inflamed, and a little welty. Not all of the welts were raised, they look like they were in the skin. There was redness and it was like someone scratched her and was kind of itchy. She took 2 diphenhydramine hydrochloride (BENADRYL). Patient was very sensitive to allergies, but was not allergic to anything. Sometimes she broke out in welts in the spring. Patient got the injection in the left side but the reaction was occurring in the right side. Patient was pretty tired, but she was concerned about the rash. Patient was concerned that the right arm was roughly 2" bigger than the left arm around it. Patient had been measuring the circumference, because nurses were paranoid about things like that. It was usually not 2" more around. Patient woke up this around 10:00 am. Around roughly 12:20 pm, or probably 10 after 12, she looked in the mirror and said there it was. She noticed the itching and thought it was dry skin. That area was prone to dry skin. The welty points of redness that were raised. It looked like someone had scratched across the area. It was red, and might be the end of one red scratchy area might be a bump. It looked like, if were to put hand where the nipple used to be and open up the area. That would all be covered. It included the upper arm and the inside of the shoulder, like the front side of the shoulder. It was raised and welty redness. Not all areas were raised and was bumpy. It was all pretty red and warm to the touch. The itchiness started more after she saw it, which was terrible. Patient took diphenhydramine hydrochloride because she was concerned about an allergic reaction. She also had scheduled medications that she took in the morning. Patient took 50 mg diphenhydramine hydrochloride this morning. Patient took at 12:10 pm when noticed these things. At first, she didn't think anything, she didn't think like it was the Pfizer shot or anything. It was just a normal day. Diphenhydramine hydrochloride had done nothing for the welts yet. Patient then felt kind of nauseated. It started when we first got on the phone. She couldn't put her finger on it. Patient went to the emergency room last Monday. The incident had nothing to do with any vaccine. She had chest pain and shortness of breath. They drew all of the labs. If she wanted to know if anything in the labs was different from then and now, she could. Everything was normal. She got an inhaler. They though it might be related to all of her allergies. The only way she would go see a doctor, is if she saw that the arm was getting much bigger, like it grew 2" more. If she had a hard time breathing, she would call 911. Patient had rash around right arm on 20Apr2021, in area of past breast mastectomy. Patient first noticed itching and the redness around 12:20 pm on 20Apr2021. Had gotten progressively worse. Patient did not see in the emergency department and was not hospitalized. Patient was not admitted to an Intensive Care Unit. Multiorgan were involved. Patient just noticed new area that formed. There were lines coming out of the area and came below the sleeve line. The red rash was spreading. It looked like something invisible scratched it. There was a triangle of three dots with a little scratch mark below the sleeve. There was another dot area on the forearm that itches, just like the other stuff did. Stomach had been feeling a little jumpy. Patient had already eaten breakfast. It was not horrible. Patient would watch it and drink ginger ale. Patient was asking what parameters should be for calling 911. She was home alone. This was not life threatening but if it turned into something bigger or if she noticed getting a bigger rash, she might have to call 911. Outcome of the events was unknown.  No follow-up attempts are needed; information about lot/batch number cannot be obtained.