What happened, in summary

A 49-year-old woman had a history of left breast cancer treated 7 years earlier, when she was 38. The breast cancer was pT2N2M0, Stage IIIA. She underwent left modified radical mastectomy followed by adjuvant chemotherapy with doxorubicin, cyclophosphamide, and docetaxel, plus regional radiotherapy. This later presentation did not demonstrate Stage IV breast cancer or lung metastasis. Seven years after her breast cancer treatment, she developed general malaise, and chest imaging showed increasing infiltration in the left lung field. CT demonstrated ground-glass opacity in the left lower lung. After 1 year, she developed dry cough and chest discomfort, and repeat CT showed that the ground-glass opacity had progressed. Because the appearance raised concern for malignancy, including bronchioloalveolar carcinoma, she underwent thoracoscopic lobectomy of the left lower lung. Pathology did not show breast cancer recurrence or a new lung cancer. Instead, it showed chronic inflammatory cells and alveolar spaces filled with CD163-positive foamy histiocytes and proteinaceous exudates, consistent with lipid pneumonia. At 1 year after surgery, she was asymptomatic. Surveillance CT showed newly developed mixed consolidation and ground-glass opacity in the right middle lung, so ongoing imaging follow-up was planned. Her clinical status is best understood as survivorship after completed breast cancer treatment with a benign lung mimic, not metastatic breast cancer with lung spread. She had no history of oil ingestion, and the suspected lung cancer diagnosis was resolved only after surgical pathology. Because new right-lung opacity remained under surveillance, the situation remained completed breast cancer treatment with continued imaging follow-up rather than definitive proof of a new malignancy.