RESUMEN
BACKGROUND: A woman aged 75 years presented with a palpable left axillary lymph node. Mammography showed a spiculated mass in the left breast, demonstrated by biopsy to be triple-negative breast cancer. A positron emission tomography-computed tomography (PET-CT) scan was performed to evaluate the extent of the cancer and revealed an unrelated nonmetastatic, synchronous carcinoid in the left lung. The patient was a nonsmoker and presented with no symptoms of lung disease. DISCUSSION: Advanced imaging modalities used to evaluate the extent of locally advanced breast cancer have been a keystone in decreasing cancer mortality rates. Mammography is considered the gold standard for breast disease evaluation, but sonography is a valuable modality for correlating suspicious findings and evaluating lesions that might not be visible on mammograms. When a breast biopsy confirms metastasis to the axillary lymph nodes, PET-CT is the modality of choice for cancer staging and ruling out distant metastases. CONCLUSION: Imaging tools used to evaluate breast cancer can help determine whether distant metastasis has occurred and in rare cases can help discover other primary cancers. The patient in this case study was 1 of the few patients with an incidental finding of a second nonmetastatic primary malignancy in the lung detected using PET-CT. The risks associated with advanced imaging include exposing patients to additional tests and potentially invasive procedures based on the results. However, in some instances, imaging results can alter the treatment plan and increase survival rates. Further empirical research and case studies are needed to identify clinical outcomes for patients with a second primary cancer.