A case report of synchronous breast and lung cancer with three different pathologic diagnoses.

Background: Multiple primary malignant tumors (MPMTs) pose a significant clinical challenge, denoting the occurrence of two or more distinct malignant tumors with differing histological characteristics, all diagnosed within a 6-month timeframe. MPMT is a rare condition and due to the unique treatment requirements for each specific cancer type, it is crucial for healthcare professionals to accurately differentiate between metastatic growth and distinct primary tumors. Case Description: In this case report, we present a 41-year-old female patient who received diagnoses of three separate synchronous primary tumors. The patient presented for evaluation of a right breast mass that had been present for 1 year. Initial diagnostic tests, including mammography and ultrasound, did not provide any conclusive results. Subsequent magnetic resonance imaging (MRI) of the breast prompted an ultrasound-guided biopsy which confirmed moderately differentiated invasive ductal carcinoma (IDC). During pre-surgical testing, a suspicious opacity was detected on a chest X-ray, prompting further investigation with a computed tomography (CT) scan of the chest to distinguish between metastatic disease and a potential new primary tumor. Clinical and pathological examinations revealed the presence of bilateral masses originating from two different origins: invasive mucinous pulmonary adenocarcinoma in the left lower lobe and a neuroendocrine carcinoma in the right middle lobe of the lung. Conclusions: Cases of this nature present a complex challenge to physicians and underscore the critical importance of maintaining a high level of clinical suspicion to ensure the delivery of high-quality care. Effective management of such patients requires a multidisciplinary collaboration among breast surgeons, thoracic surgeons, and medical and radiation oncologists.