Triple negative invasive ductal carcinoma; Triple negative invasive ductal carcinoma; Ipsilateral right-sided node; Contralateral nodes/left sided; This literature-non-study case was reported in a literature article and describes the occurrence of INVASIVE DUCTAL BREAST CARCINOMA (Triple negative invasive ductal carcinoma), TRIPLE NEGATIVE BREAST CANCER (Triple negative invasive ductal carcinoma) and METASTASES TO LYMPH NODES (Ipsilateral right-sided node) in a 41-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.   LITERATURE REFERENCE:     Concurrent medical conditions included Breast cancer.    On an unknown date, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, the patient experienced INVASIVE DUCTAL BREAST CARCINOMA (Triple negative invasive ductal carcinoma) (seriousness criterion medically significant), TRIPLE NEGATIVE BREAST CANCER (Triple negative invasive ductal carcinoma) (seriousness criterion medically significant), METASTASES TO LYMPH NODES (Ipsilateral right-sided node) (seriousness criterion medically significant) and LYMPHADENOPATHY (Contralateral nodes/left sided). At the time of the report, INVASIVE DUCTAL BREAST CARCINOMA (Triple negative invasive ductal carcinoma), TRIPLE NEGATIVE BREAST CANCER (Triple negative invasive ductal carcinoma), METASTASES TO LYMPH NODES (Ipsilateral right-sided node) and LYMPHADENOPATHY (Contralateral nodes/left sided) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Biopsy breast: Core biopsies of the right breast mass revealed triple negative invasive ductal carcinoma and enlarged lymph node demonstrated findings concerning for malignant involvement.. On an unknown date, Breast scan: as a 1.5 cm round right breast mass with a 0.8 × 0.8 × 0.7 cm ipsilateral axillary lymph node.. On an unknown date, Magnetic resonance imaging breast: Breast MRI (Performed three weeks after whole body 18F-FDG PET/CT). Axial T1 weighted post-contrast image shows enhancing and enlarged lymph node with asymmetric cortical thickening and a biopsy clip in the right axilla. Axial T1 weighted post-contrast image, obtained slightly below the level of image in, shows a cluster of reactive lymph nodes in the left axilla with no significant enhancement or asymmetric cortical thickening. An additional right axillary node with asymmetric cortical thickening is also seen, highly suspicious for metastatic disease. and Contrast enhanced breast magnetic resonance imaging (MRI; MRI study was performed before and after IV gadolinium administration) approximately 5 weeks post-vaccination and prior to any treatment revealed stable bilateral axillary nodes. However, there were differences in imaging characteristics of lymph nodes. The right axillary lymph node demonstrated eccentric cortical thickening and contrast enhancement, whereas the left axillary lymph nodes showed clear delineation of fatty hila without discernable enhancement on post contrast images. The latter is typically suggestive of a benign etiology such as inflammation/infection.. On an unknown date, Physical examination: presented with palpable right breast lump and ipsilateral axillary nodal enlargement.. On an unknown date, Positron emission tomogram: (Preoperative imaging studies) Whole-body, 18F-FDG PET/CT, 3D MIP image shows intensely hypermetabolic malignant lesion in the right breast with SUV max 19.2, and ipsilateral involved 1.4 × 0.8 cm axillary node moderately hypermetabolic solitary lymph node in the right axilla with SUV max 5.0 [Deauville score = 5] and two mildly hypermetabolic lymph nodes in the left axilla nodes measuring 1.0 × 0.8 cm with SUV max 2.6. which was above the activity of mediastinal blood pool of SUV max 2.3, [Deauville score = 3] were identified.  Fused axial image shows the intense FDG avid malignant lesion in the right breast with SUV max of 19.2. Fused axial image shows a moderately hypermetabolic lymph node in the right axilla with SUV max of 5.0. Fused axial image shows two mildly avid lymph nodes in the left axilla with SUV max of 2.6. and Follow-up post operative whole-body 18F-FDG PET-CT 3D MIP image shows no residual hypermetabolic activity in the right breast, no hypermetabolic activity in the right axilla, and resolution of moderately hypermetabolic left axillary lymph nodes. Fused axial image shows resolution bilateral lymph nodes..     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered LYMPHADENOPATHY (Contralateral nodes/left sided) to be related. No further causality assessments were provided for INVASIVE DUCTAL BREAST CARCINOMA (Triple negative invasive ductal carcinoma), TRIPLE NEGATIVE BREAST CANCER (Triple negative invasive ductal carcinoma) and METASTASES TO LYMPH NODES (Ipsilateral right-sided node).    Concomitant medications were not provided.  No specific treatment medication reported.  Pre-menopausal patient presented with palpable right breast lump and ipsilateral axillary nodal enlargement. The left axillary lymph nodes were initially considered indeterminate for metastatic disease, but upon further review, they were attributed to the second dose of the Moderna mRNA COVID-19 vaccine which was administrated to the left arm sixteen days previously.  The patient completed neoadjuvant chemotherapy for triple negative disease, and a follow-up 18F-FDG PET/CT at approximately 6-months from her last 18F-FDG PET/CT showed complete resolution of the previously hypermetabolic bilateral lymph nodes. Patient underwent a right mastectomy and complete axillary node dissection, the final surgical specimen demonstrated complete histopathological response to neoadjuvant systemic therapy with treatment-related changes.  Author concluded nodal enlargement persisted beyond 6 weeks. Current expert recommendations for follow-up are ongoing and include follow-up of the affected axilla at least 6-weeks after the second dose of the vaccination, with consideration for lymph node sampling if suspicion remains. The follow-up to resolution particularly in those with known underlying malignancies should warrant careful consideration, and documentation of vaccination should be included to assist the interpreting radiologist.  Company comment: This literature non-study case concerns a 41 year old pre-menopausal woman with concurrent condition of breast cancer, who experienced the unexpected serious (medically significant) events of Invasive ductal breast carcinoma, Triple negative breast cancer and Metastases to lymph nodes, after the recent (16 days) administration of the second dose of mRNA-1273 vaccine. The patient presented with palpable right breast lump and ipsilateral axillary nodal enlargement post recent vaccination. This was subsequently confirmed by breast imaging as a 1.5 cm round right breast mass with a 0.8 × 0.8 × 0.7 cm ipsilateral axillary lymph node. Core biopsies of the right breast mass revealed triple negative invasive ductal carcinoma and enlarged lymph node demonstrated findings concerning malignancy. Staging 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) showed an intensively FDG avid right axillary tail breast primary and ipsilateral involved 1.4 × 0.8 cm axillary node (SUVmax 5.0, [Deauville score = 5], Additionally, mildly FDG avid left axillary nodes measuring 1.0 × 0.8 cm (SUVmax 2.6, which was above the activity of mediastinal blood pool of SUVmax 2.3, [Deauville score = 3] were identified. The left axillary lymph nodes were initially considered indeterminate for metastatic disease, but upon further review, they were attributed to the second dose of the Moderna mRNA COVID-19 vaccine which was administrated to the left arm sixteen days previously. Contrast-enhanced breast magnetic resonance imaging approximately 5 weeks post-vaccination and prior to any treatment revealed stable bilateral axillary nodes. However, there were differences in imaging characteristics of lymph nodes. The right axillary lymph node demonstrated eccentric cortical thickening and contrast enhancement, whereas the left axillary lymph nodes showed clear delineation of fatty hila without discernable enhancement on post contrast images. The latter is typically suggestive of a benign etiology such as inflammation/infection. The patient completed neoadjuvant chemotherapy for triple negative disease, and a follow-up 18F-FDG PET/CT at approximately 6-months from her last 18F-FDG PET/CT showed complete resolution of the previously hypermetabolic bilateral lymph nodes. She underwent a right mastectomy and complete axillary node dissection, the final surgical specimen demonstrated complete histopathological response to neoadjuvant systemic therapy with treatment-related changes. Authors concluded that ipsilateral axillary nodal reactivity is a common observation after administration of the second dose of COVID-19 mRNA vaccines, with the potential persistence up to several months. In the current case, nodal enlargement persisted beyond 6 weeks. Authors concluded that current expert recommendations suggest follow-up of the affected axilla at least 6-weeks after the second dose of the vaccination, with consideration for lymph node sampling if suspicion remains. The follow-up to resolution particularly in those with known underlying malignancies should warrant careful consideration, and documentation of timing and location of the vaccination and imaging characteristics should all be considered. Concurrent condition of breast cancer could be confounding the events Invasive ductal breast carcinoma, Triple negative breast cancer and Metastases to lymph nodes. The benefit-risk relationship of mRNA-1273 is not affected by this report.   Most recent FOLLOW-UP information incorporated above includes: On 01-Dec-2022: Live follow up received by safety on 02-DEC-2022 has Email with FTA received and contains significant information: Reporter information, literature information, medical history, laboratory details, product details and event details were updated.; Sender's Comments: This literature non-study case concerns a 41 year old pre-menopausal woman with concurrent condition of breast cancer, who experienced the unexpected serious (medically significant) events of Invasive ductal breast carcinoma, Triple negative breast cancer and Metastases to lymph nodes, after the recent (16 days) administration of the second dose of mRNA-1273 vaccine. The patient presented with palpable right breast lump and ipsilateral axillary nodal enlargement post recent vaccination. This was subsequently confirmed by breast imaging as a 1.5 cm round right breast mass with a 0.8 × 0.8 × 0.7 cm ipsilateral axillary lymph node. Core biopsies of the right breast mass revealed triple negative invasive ductal carcinoma and enlarged lymph node demonstrated findings concerning malignancy. Staging 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) showed an intensively FDG avid right axillary tail breast primary and ipsilateral involved 1.4 × 0.8 cm axillary node (SUVmax 5.0, [Deauville score = 5], Additionally, mildly FDG avid left axillary nodes measuring 1.0 × 0.8 cm (SUVmax 2.6, which was above the activity of mediastinal blood pool of SUVmax 2.3, [Deauville score = 3] were identified. The left axillary lymph nodes were initially considered indeterminate for metastatic disease, but upon further review, they were attributed to the second dose of the Moderna mRNA COVID-19 vaccine which was administrated to the left arm sixteen days previously. Contrast-enhanced breast magnetic resonance imaging approximately 5 weeks post-vaccination and prior to any treatment revealed stable bilateral axillary nodes. However, there were differences in imaging characteristics of lymph nodes. The right axillary lymph node demonstrated eccentric cortical thickening and contrast enhancement, whereas the left axillary lymph nodes showed clear delineation of fatty hila without discernable enhancement on post contrast images. The latter is typically suggestive of a benign etiology such as inflammation/infection. The patient completed neoadjuvant chemotherapy for triple negative disease, and a follow-up 18F-FDG PET/CT at approximately 6-months from her last 18F-FDG PET/CT showed complete resolution of the previously hypermetabolic bilateral lymph nodes. She underwent a right mastectomy and complete axillary node dissection, the final surgical specimen demonstrated complete histopathological response to neoadjuvant systemic therapy with treatment-related changes. Authors concluded that ipsilateral axillary nodal reactivity is a common observation after administration of the second dose of COVID-19 mRNA vaccines, with the potential persistence up to several months. In the current case, nodal enlargement persisted beyond 6 weeks. Authors concluded that current expert recommendations suggest follow-up of the affected axilla at least 6-weeks after the second dose of the vaccination, with consideration for lymph node sampling if suspicion remains. The follow-up to resolution particularly in those with known underlying malignancies should warrant careful consideration, and documentation of timing and location of the vaccination and imaging characteristics should all be considered. Concurrent condition of breast cancer could be confounding the events Invasive ductal breast carcinoma, Triple negative breast cancer and Metastases to lymph nodes. The benefit-risk relationship of mRNA-1273 is not affected by this report.