Multiple Lung Cancers: Independent Primary Tumors or Intrapulmonary Metastases, A Case Report

Abstract Background The prevalence of multiple primary lung cancers is rising, highlighting the need for tools to distinguish independent primary tumors from metastases. Molecular markers and hisopathologic comparison are useful to aid in this distinction, but they have significant limitations. Case Presentation A 76-year old woman presented with recurrent bronchorrhea, non-productive cough, and dyspnea upon exertion. She was a former smoker (15 pack-year history). Computerized tomography imaging revealed multiple lung masses: 1.9 × 2.3 cm nodule in the right upper lobe, and a 6.5 cm mass in the right lower lobe. Histologic examination of the tumors showed that the right lower lobe mass was an adenosquamous carcinoma with a mucinous adenocarcinoma component. This tumor showed visceral pleural invasion, and direct invasion of one intrapulmonary peribronchial lymph node. The upper lobe lesion was characterized by pure invasive mucinous adenocarcinoma with no squamous component. Abdominal and pelvic imaging was performed to rule out alternative primary sites, and no evidence of disease was identified outside of the chest. A cancer mutation and rearrangement panel on the adenosquamous carcinoma did not reveal any mutations. Conclusions In this interesting case, a patient presented with two lung tumors which had some morphologic similarities, but also some important differences, and no specific genetic mutations were present to establish the relationship between the tumors. Although current tools are useful, this case highlights an example of a case where it remains extremely difficult to determine whether two lung cancers are independent primary tumors or intrapulmonary metastases.