Neoplastic and nonneoplastic benign mass lesions of the lung.

While most lung neoplasms are malignant, a subset of true neoplasms are benign, the most common of which are pulmonary hamartomas. In addition, a substantial proportion of lung mass lesions are nonneoplastic; granulomas are among the commonly encountered nonneoplastic masses. There is also a group of relatively rare, mainly inflammatory and fibrous tumor-like lesions that are encountered on core biopsy and excisions of lung tissue.