[Morphological diagnosis and classification of lung tumors]

Morphologic examination is mandatory for distinction between benign and malignant pulmonary lesions and separation of primary tumors from metastatic disease. Tumors are classified as to their type and grade by histology and/or cytology. Differences in behavior and response to treatment make the distinction between small cell carcinoma [SCLC] and non-small cell carcinoma [NSCLS] the single most important decision the pathologist must make when examining a lung tumor. The considerable cellular heterogeneity of bronchogenic carcinoma may be the source of problems and pitfalls in morphologic classification of these tumors, discussed in this review together with the concept of neuroendocrine neoplasms.