Background: Sarcoidosis is an inflammatory disease that affects multiple organs in the body, especially the lungs and lymph nodes. The coexistence of sarcoidosis and breast cancer has been reported, but the coexistence of both diseases in the same patient often leads to misdiagnosis. Case: We report a case of a 36-year-old woman who presented with concerns of a lump in her left breast along with pain and discharge from the nipple. On examination a 3-cm hard and tender mass was noted in the upper medial quadrant of the left breast with no palpable axillary lymph nodes. The patient was diagnosed with an infiltrating ductal cell carcinoma of the left breast with T2N0M1 Stage IV disease, due to positive mediastinal lymphadenopathy on positron emission tomography scan. The biopsy of mediastinal lymph nodes allowed us to diagnose sarcoidosis and correctly stage her disease as T2N0M0 Stage IIA breast cancer. The patient underwent lumpectomy followed by adjuvant chemo radiotherapy and hormonal therapy - corticosteroids given for sarcoidosis up to 1 year. The patient is doing well 18 months later without recurrence of disease. Conclusion: The simultaneous occurrence of both diseases in the same patient is the risk for misdiagnosis and mismanagement, therefore it is of utmost importance to correctly stage the disease with appropriate investigations and histologic confirmation prior to initiate the treatment for breast cancer.