Background: Lung is the third most frequent identified site of malignancy and lung cancer is the most lethal type of cancer in the world. Several benign lung diseases or proliferations may mimic lung carcinoma in its clinical, pathological, and radiological presentation, which makes the differential diagnosis life changing. This case series was designed to describe the main diagnosis encountered in a multidisciplinary emergency hospital during the last years in Romania. Results: The most challenging cases encountered during the recent years were those of lung hamartoma associated with eosinophilic pneumonia because of the multicentricity of the disease and the suspicion for metastasis in the clinical setting, pulmonary aspergillosis that presented as a cystic lesion with a 9 mm mural nodule, actinomycosis discovered as firm nodule showing aspects of false pleural invasion, cryptococcosis -a hilar mass for which a pneumectomy was prepared, pulmonary parasitosis that presented as a nodule with irregular borders, causing pleural retraction, one case of inflammatory myofibroblastic tumor of the lung, one case of tumorlet type neuroendocrine lesion in a patient with history of melanoma and renal oncocytoma, admitted under the suspicion of lung metastasis. Conclusions: These are some of the main mimickers of primary or secondary lung cancers and one must be aware of these similitudes to avoid higher cost procedures, psychological stress for the patient and higher mortality.