Bilateral Axillary Lymphadenopathy; fever; chills; pain at the injection site; The initial case was missing the following minimum criteria: unspecified suspect product. Upon receipt of follow-up information on 19Apr2023, this case now contains all required information to be considered valid.  This is a literature report.  A 62-year-old male patient received BNT162b2 (BNT162B2), on 12Jan2021 as dose 2, single (Batch/Lot number: unknown) at the age of 62 years, in right arm for covid-19 immunisation. The patient's relevant medical history included: "well-controlled hypertension" (unspecified if ongoing); "gastroesophageal reflux" (unspecified if ongoing). The patient's concomitant medications were not reported. Vaccination history included: pfizer-biontech coviD-19 vaccine (BNT162b2) (Dose 1, single, intramuscularly in right upper extremity), administration date: 22Dec2020, for COVID-19 immunisation, reaction(s): "pain at the injection site"; Bacillus calmette-guerin (bcg) vaccination (when he was a child); Influenza vaccinations (annually received).  The following information was reported: INJECTION SITE PAIN (non-serious) with onset 12Jan2021, outcome "unknown", described as "pain at the injection site"; CHILLS (non-serious) with onset 13Jan2021, outcome "recovering"; PYREXIA (non-serious) with onset 13Jan2021, outcome "recovering", described as "fever"; LYMPHADENOPATHY (hospitalization, medically significant, life threatening) with onset 14Jan2021, outcome "recovering", described as "Bilateral Axillary Lymphadenopathy"; SEROMA (medically significant), outcome "recovered" (2021), described as "left-sided fluid collection where the axillary mass was removed/seroma recurred". The patient underwent the following laboratory tests and procedures: Biopsy lymph gland: (unspecified date) preliminary report while in operating room, notes: revealed a fatty lymph node negative for malignancy; Blood cholesterol (normal high range 200): (2021) 173 mg/dl, notes: Reference interval: low, <200; Blood pressure diastolic: (unspecified date) 68 to 82 mmHg; Blood pressure systolic: (unspecified date) 108 to 136 mmHg; Blood test: (24May2021) unknown results; Blood triglycerides (200-499): (2021) 272 mg/dl, notes: Reference interval: high, 200-499; Computerised tomogram: (24May2021) no axillary lymphadenopathy, notes: However, soft tissue swelling was observed with calcified encapsulation; Electrophoresis: (2021) all immunoglobulins were within normal limits; Haematocrit (41-50): (2021) 46.9 %; Haemoglobin (13-18): (2021) 16.2 g/dl; Heart rate: (unspecified date) 72 to 89 beats per minute; High density lipoprotein (normal low range 40): (2021) 40 mg/dl, notes: Reference interval: desirable, >40; Histology: (unspecified date) Left axillary mass, one benign lymph node with, notes: benign lipomatosis; Immunology test: (2021) all immunoglobulins were within normal limits; Low density lipoprotein (normal high range 100): (2021) 88 mg/dl, notes: Reference interval: optimal, <100; Platelet count (150-400): (2021) 147 x10 9/l; SARS-CoV-2 antibody test (normal high range 0.8): (2021) 929 IU/ml, notes: Unit: u/ml, suggesting adequate antibody creation to the virus after the administration of the vaccine. Reference interval: negative result, <0.8; Ultrasound scan: (2021) unknown results; White blood cell count (4.5-10.5): (2021) 8.7 x10 9/l. Therapeutic measures were taken as a result of lymphadenopathy, seroma, pyrexia, chills.  Clinical course: The patient was reported to be a registered nurse who received his first dose of Pfizer-BioNTech COVID-19 vaccination on 22Dec2020. At this time, the FDA issued the first emergency use authorization for the use of the Pfizer-BioNTech COVID-19 vaccine. This vaccine was recommended for people aged 16 years and older. Healthcare personnel and long-term care facility residents were offered COVID-19 vaccination first (phase 1a). Immediately following the vaccination administration intramuscularly in his right upper extremity, the patient experienced pain at the injection site with no additional adverse side effects. Twenty-one days later, on 12Jan2021, the patient was inoculated again in his right upper extremity with the second dose of the Pfizer-BioNTech COVID-19 vaccine. After receiving the second dose, the patient started to experience his unique side effects. Beginning on day 0, the day the second dose of the vaccine was administered, the patient noted slight pain at the injection site. This localized pain was less when compared to the first injection received 21 days prior. On day 1 after the second vaccine, the patient felt subjective fever and chills and took 800 mg of acetaminophen every six hours for a total of two doses and noted improvement. On day 2, the patient had self-identified painless lymphadenopathy under his right axilla and was initially noted to be small and mobile, with an estimated size of 1 cm x 1 cm. Over the next 30 days, the patient noticed axillary lymphadenopathy starting to develop in his left axilla as well, contralateral to the side of the injection. Over the next three to four months, bilateral axillary masses gradually grew larger with the left becoming slightly tender to palpation and increasing in firmness. It was also important to note that the patient had never experienced side effects like this in the past following vaccinations. Since the patient was a healthcare worker, he annually received influenza vaccination with no similar side effects. The patient also received the Bacillus Calmette-Guerin (BCG) vaccination when he was a child, again with no similar side effects of lymphadenopathy. Four months after his second vaccination, when it was apparent that the patient's bilateral axillary lymphadenopathy was not self-limiting, he decided to seek medical attention from his primary care physician. It was recommended that the patient obtain a non-contrast chest computed tomography (CT) scan of the left axilla along with routine blood work. The imaging study was performed, and blood samples were collected on 24May2021, four months after the administration of the second dose of the COVID-19 vaccination. The CT scan identified no axillary lymphadenopathy. However, soft tissue swelling was observed with calcified encapsulation. Initially, there was a concern for malignancy such as lymphoma or leukemia, multiple myeloma, any other systemic disease, or infection. Complete blood count (CBC) with differential was within normal limits, including a white blood count of 8.7 × 10 9/L, hemoglobin of 16.2 g/dL, hematocrit of 46.9%, and platelets of 147 × 10 9/L. Serum immunofixation (IFE) and electrophoresis (EP) revealed that all immunoglobulins were within normal limits as well. The cholesterol panel was grossly unremarkable with cholesterol at 173 mg/dL, triglycerides elevated at 272 mg/dL, high-density lipoprotein (HDL) at 40 mg/dL, and low-density lipoprotein (LDL) at 88 mg/dL. The results of the SARS-COV-2 antibodies identified a level of 929 u/mL, suggesting adequate antibody creation to the virus after the administration of the vaccine; it is considered a negative interpretation if the value is <0.8 u/mL. Seven months after the second dose of the Pfizer-BioNTech COVID-19 vaccine, the bilateral axillary lymphadenopathy continued to remain stable in size with no regression noted and no significant changes identified. The bilateral axillary lymphadenopathy was measured, and it was estimated that the right axillary mass externally measured 9 cm x 5 cm, and the left axillary mass externally measured 7 cm x 6 cm. The patient reported no additional symptoms except the ones previously mentioned. With the seemingly normal laboratory findings and imaging, the patient's primary care physician was starting to narrow their differential. It still could not be fully ruled out that this was a potential malignancy due to the uncharacteristic nature of the persistent, non-self-limiting, bilateral axillary lymphadenopathy. It was then that the patient sought out further medical attention, in the form of a general surgeon. The general surgeon recommended surgical resection of the left axillary mass with the specimen being sent to pathology as a frozen section to verify and rule out malignancy. Upon arrival at the operating room, a complete history was obtained. The procedure was performed under general anesthesia. For induction, fentanyl 100 mcg, propofol 150 mg, and rocuronium 50 mg were given. The patient was easy to mask ventilate and was intubated with direct laryngoscopy using a Mac-3 blade and insertion of a size 7.5 endotracheal tube; a grade 1 view was observed during intubation. Throughout the entirety of the case, the patient was maintained on volatile anesthetics, a combination of sevoflurane (2%-3%) and nitrous oxide (50%) with oxygen (50%) at a flow rate varying from 2 to 3 L. The patient remained extremely hemodynamically stable throughout the case with a systolic blood pressure (SBP) ranging from 108 to 136 mmHg, a diastolic blood pressure (DBP) ranging from 68 to 82 mmHg, and a heart rate (HR) ranging from 72 to 89 beats per minute. The patient tolerated the procedure well, and immediately following the removal of the right axillary lymph node, it was sent to pathology. The preliminary report while in the operating room revealed a fatty lymph node negative for malignancy. Once the incision closure was completed, the patient was fully reversed with neostigmine 4 mg and glycopyrrolate 0.8 mg. The patient was ready for extubation and noted to have adequate minute ventilation, sustained head lift, and sustained tetanus. The patient was extubated without any complications and subsequently taken to the post-anesthesia care unit (PACU) where he was then observed for the next 60 minutes and was discharged the same day. The patient had a follow-up appointment with the general surgeon one week later, where his surgical incision was healing well and the sutures were removed. The official pathology report was also available at this time and identified the mass as one benign lymph node with benign lipomatosis. It was reported as the surgical pathology report of the frozen section left axillary mass that was surgically excised showed left axillary mass, one benign lymph node with benign lipomatosis. At the one-week follow-up appointment, it was also noted that there was a left-sided fluid collection where the axillary mass was removed. A sterile needle was inserted, and the fluid collection was drained, removing a total of 50 cc of clear fluid that was determined to be a seroma. The patient was then seen weekly by the surgeon for close monitoring and further evaluation of the left axillary region. At the next four weekly visits, the seroma recurred and each time was drained with 50 cc removed. On the final weekly evaluation, the seroma was again drained, but only 10 cc of fluid was removed. Six weeks after the surgical procedure, there was no recurrence of the seroma. At his three-month follow-up appointment with the general surgeon and primary care physician, the patient did not have any recurrence of the left-sided axillary lymphadenopathy or seroma formation, and his surgical site was well-healed. The right axillary lymphadenopathy continued to remain present with no signs of regression.; Sender's Comments: Based on the information provided, a causal relationship between suspect drug BNT162b2 and the reported event 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,Linked Report(s) : US-PFIZER INC-202300164523 Same article/patient and different drug/event;