[Pulmonary tumors]

Pulmonary nodules may be caused by true neoplasms of the airways, respiratory epithelium, vessels and connective tissue which are mainly malignant or metastatic. They may, however, also represent mainly inflammatory benign pseudotumours. Non-small cell lung cancer (NSCLC) usually presents as an ill-defined soft-tissue pulmonary nodule or mass, often without lymphadenopathy; endobronchial lesions are less common. Small cell lung cancer (SCLC) commonly presents with extensive lymph node and hematogenous metastases. Carcinoid tumors typically manifest as endobronchial lesions with secondary obstruction. Sarcomas are rare and show variable morphology. Metastases most commonly present as basal, peripheral, well-defined nodules. Granulomas often exhibit typical calcifications; hamartoma may also contain popcorn-type calcifications as well as fat. Pulmonary arteriovenous malformation is characterised by feeding artery and draining vein. Inflammatory nodules are well vascularized and may regress spontaneously; their differentiation from malignant lesions, however, is usually difficult.