Benefit of a second opinion: From metastatic disease to resectable lung cancer with sarcoid-like reaction

Background: Mediastinal lymphadenopathy in combination with lung cancer is suggestive for lymph node metastases but can also have other origins. Case report: We describe a patient diagnosed with stage IV lung cancer presenting with parenchymal lesions and enlarged mediastinal lymph nodes. A second opinion including FDG-PET scan review and a mediastinoscopy followed by surgery revealed tumor specimens originating from a single primary tumor with a sarcoid-like reaction in the mediastinal lymph nodes, changing the diagnosis from metastasized to resectable lung cancer. Discussion: PET positive lesions are not always synonymous with metastatic disease in the presence of a malignant tumor. Conscientious review of FDG-PET scans and tissue sampling are therefore mandatory to determine definitive staging and subsequent interventions.