Anatomic Pathology: Cytopathology

• For a sputum sample to be considered adequate, alveolar macrophages must be present; otherwise, the specimen may consist of only saliva. There is no numerical cut-off point for macrophages in sputum; however, an adequate specimen should have numerous easily identifiable pulmonary alveolar macrophages. The presence of macrophages is also important in bronchoalveolar lavage (BAL) specimens. The presence of these cells confirms that the specimen originated from the deeper portions of the respiratory tract. The greater the number of pulmonary alveolar macrophages, the more likely it is that the respiratory sample is adequate.

• Although spontaneous sputum has limited value in the evaluation of pulmonary diseases, induced sputum may provide valuable information about benign (e.g., pneumocystis infection) and malignant pulmonary conditions.

• Bi-, tri-, and multinucleated macrophages may be seen in respiratory specimens and do not necessarily indicate a disease process.

• In conditions of chronic irritation, large numbers of goblet cells may be detected in bronchial brushings, bronchial aspirates, and sputum. For example, goblet cell hyperplasia may be seen in cases of asthma, chronic bronchitis, and bronchiectasis.

• Macrophages containing phagocytized lipid (lipophages) are increased in number in cases of lipoid pneumonia, the fat embolism syndrome, pulmonary aspiration (for example, in infants with aspiration pneumonia), and amiodarone pulmonary toxicity. These cells appear as small, finely vacuolated macrophages and are not readily identified in papanicolaou-stained preparations; however, stains for Oil Red-O or Sudan black performed on fresh (unfixed) specimens highlight the presence of lipid in the cells.

• Pulmonary alveolar macrophages containing phagocytized hemosiderin (siderocytes) are the result of hemorrhage in the pulmonary parenchyma. The hemosiderin appears in the cytoplasm as a golden brown crystalline pigment.