Cytology is the study of the origin, structure, function, and pathology of cells. In clinical practice, cytological examinations are generally performed to detect cell changes resulting from neoplastic or inflammatory conditions. Sputum specimens for cytological examinations may be collected by expectoration alone, by suctioning, by lung biopsy, during bronchoscopy, or by expectoration after bronchoscopy. A description of the method of specimen collection by bronchoscopy and biopsy is found in the monograph titled “Biopsy, Lung.”