biopsy of the left axillary lymph node yielded metastatic invasive lobular carcinoma/breast; This is a literature report for the following literature source(s):  An 81-year-old female patient received BNT162b2 (BNT162B2), as dose 1, single (Batch/Lot number: unknown), in left arm for covid-19 immunisation. The patient's relevant medical history and concomitant medications were not reported. The following information was reported: INVASIVE LOBULAR BREAST CARCINOMA (medically significant), 12 days after the suspect product(s) administration, outcome "recovering", described as "biopsy of the left axillary lymph node yielded metastatic invasive lobular carcinoma/breast". The patient underwent the following laboratory tests and procedures: Biopsy: interval clinical resolution of the left breast, notes: edema and skin thickening, but a new lump in the left upper outer breast was found that corresponded to a 10.8 x 7.1 x 10.0 mm irregular hypoechoic mass on targeted ultrasound; breast mass yielded estrogen, notes: receptor-positive, progesterone receptor-positive, HER2-negative invasive lobular carcinoma; Computerised tomogram thorax: no findings, notes: to suggest a systemic cause or fluid overload; obtained to exclude systemic fluid overload show, notes: obtained to exclude systemic fluid overload show multiple enlarged left axillary lymph nodes, largest node pulmonary artery; measuring 26 x 16 mm; left breast skin thickening, notes: measuring 26 x 16 mm; left breast skin thickening (arrow, C); and left breast and axillary edema (star) without fluid collection or abscess; Diagnostic aspiration: metastatic invasive lobular carcinoma, notes: of the left axillary lymph node; Echocardiogram: no evidence of cardiac abnormality; Human epidermal growth factor receptor negative: negative; Magnetic resonance imaging: A, Axial postcontrast subtraction image shows, notes: 21 x 13 x 18 mm mass in left upper central breast containing susceptibility artifact from biopsy clip. Level I axillary lymph nodes are partially evident. Axial postcontrast subtraction image shows multiple enlarged left level I axillary lymph nodes more clearly than does A. More posterior lymph node is biopsied lymph node and contains biopsy clip. Axial STIR image shows asymmetric left breast skin edema and parenchymal edema; Mammogram: showed diffuse left breast swelling,, notes: skin thickening, parenchymal edema, and ipsilateral left axillary lymphadenopathy; Right breast has no abnormal imaging findings; unremarkable, notes: (BI-RADS category 1); Oestrogen receptor assay: Positive; Pathology test: was invasive, notes: lobular carcinoma and metastatic invasive lobular carcinoma within axillary lymph node; Physical examination: revealed no redness,, notes: warmth, or pain; Progesterone receptor assay: positive; Ultrasound breast: showed diffuse left breast swelling,, notes: skin thickening, parenchymal edema, and ipsilateral left axillary lymphadenopathy; Ultrasound Doppler: shows no associated hypervascularity, notes: Overall BI-RADS category was 4, and biopsy of suspected lymph node was recommended; shows internal, notes: hypervascularity of mass; Ultrasound scan: new lump show 10.8 x 7.1 x 10.0 mm irregular, notes: hypoechoic mass; persistent enlarged cortex measuring 8.0 mm; new lump in the left upper outer, notes: breast was found that corresponded to a 10.8 x 7.1 x 10.0 mm irregular hypoechoic mass on targeted ultrasound; enlarged node, notes: measuring 18.9 x 15.8 x 15.1 mm and exhibiting fatty hilum.  Clinical course: The patient presented with 3 days of diffuse left breast swelling. She had received the first dose of COVID-19 vaccination (Pfizer-BioNTech) in the left arm 12 days before presentation and had no personal or family history of breast cancer or ovarian cancer. Digital diagnostic mammography with tomosynthesis and complete left breast ultrasound showed diffuse left breast swelling, skin thickening, parenchymal edema, and ipsilateral left axillary lymphadenopathy. Screening mammography performed 7 years previously had been unremarkable (BI-RADS category 1). The patient had no findings to suggest a systemic cause or fluid overload on chest CT, and there was no evidence of cardiac abnormality at recent echocardiography. The patient returned for biopsy 6 weeks after the diagnostic imaging (biopsy was delayed by patient-related factors rather than a clinical recommendation). At biopsy, the patient had interval clinical resolution of the left breast edema and skin thickening, but a new lump in the left upper outer breast was found that corresponded to a 10.8 x 7.1 x 10.0 mm irregular hypoechoic mass on targeted ultrasound. Ultrasound- guided core biopsy of the breast mass yielded estrogen receptor-positive, progesterone receptor-positive, HER2-negative invasive lobular carcinoma, and fine-needle aspiration biopsy of the left axillary lymph node yielded metastatic invasive lobular carcinoma. Breast MRI performed 3 weeks after breast biopsy showed the index malignancy and multiple abnormal left axillary lymph nodes. Sender's Comments: As there is limited information in the case provided, the causal association between the reported event INVASIVE LOBULAR BREAST CARCINOMA with the suspect drug BNT162B2 cannot be excluded. The case will be reassessed once new information is available. The impact of this report on the benefit/risk profile of the Pfizer drug 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.