Case Report of Pulmonary Sarcoidosis Suspected to be Pulmonary Metastasis in a Patient with Breast Cancer.

Standard endocrine therapy and chemotherapy can induce long-term remission in breast cancer patients; however, breast cancer can recur at any site. Pulmonary nodules with lymphadenopathy in advanced cancer patients are likely to be assumed as metastases. A 44-year-old woman with a history of breast cancer was presented to our institution with abnormal findings on 18-fluorodeoxyglucose positron emission tomography imaging, which suggested lung metastasis. She had previously been diagnosed with breast cancer (T1N2M0, Stage IIIa, intraductal carcinoma, triple negative cancer). Histological analysis of the mediastinal lymph node biopsy demonstrated sarcoidosis, showing a chronic, non-caseating, granulomatous inflammation. Our case highlights the need for non-malignant diagnoses in those with prior malignancies, and the need for histological evaluations in the event of first recurrence following potentially curative therapy.