Sarcoidosis is a systemic disease with the multi-organ involvement. However, the lung involvement with hilar lymphadenopathy is the hallmark of the disease. Despite this, subtle clinical signs of sarcoidosis and non-spesific involvement of the chest by many different disorders often confound the diagnosis of this insidious disease. Therefore, it is essential to investigate common diseases of chest carefully before establishing the absolute diagnosis of sarcoidosis. In this article, we present a case of a 65 year-old woman who was admitted to the hospital with a fatigue lasting six weeks, together with a generalized body pain and left-sided chest pain propagating to the back. The patient reported anorexia with a weight loss of 4kg in this period. The initial evaluation revealed a transaminase elevation and interstitial radioopacities on the chest x-ray. The high resolution computer tomography of the chest showed the interstitial involvement and bronchiectasis. The angiotensin converting enzyme level was elevated. The bronchoalveolar lavage CD4/CD8 lymphocyte ratio was 3.39 and supported the diagnosis of sarcoidosis. The bronchoscopic biopsies were taken from airways and paratracheal lymph nodes to establish definitive diagnosis. Unlike our expectations, the biopsy revealed a breast cancer. The PET-CT, abdominal and cranial imaging showed metastases by the time of diagnosis. The trastuzumab therapy was started but the patient died as a consequence of the septic shock.