Echinococcosis (hydatid disease)

It is contracted by ingestion of Echinococcus granulosus or Echinococcus multilocularis cestode eggs, which hatch into embryos in the small intestine, enter the circulatory system and form hydatid cysts in many organs (such as the lung). In cytologic specimens, the laminated hydatid cystic wall (staining positive with PAS and methenamine silver) can be seen containing […]

Benign cellular changes

Squamous cell changes Bronchial cell changes Bronchial reserve cell hyperplasia Repair Tipe II pneumocytes hyperplasia Squamous cells Squamous cells from the upper respiratory tract often contaminate specimens from the lower tract. Inflammatory conditions of the mouth may exfoliate atypical squamous cells which should not be misdiagnosed as squamous cell carcinoma. Cancer involving head and neck […]


Hodgkin and non-Hodgkin lymphomas occur as primary tumors of the lung, but spread from an extrapulmonary primary is more common. The most common primary lymphoma of the lung is low-grade extranodal marginal zone lymphoma (MALT lymphoma), followed by diffuse large B-cell lymphoma. Low grade lymphomas are typically incidental, solitary lung masses with an indolent clinical […]


The cytologic features of common inflammatory processes, such as organizing pneumonia, bronchiolitis obliterans obstructing pneumonia and diffuse alveolar damage, are considerably overlapping. Inflammatory cells are observed, such as macrophages, neutrophils, eosinophils and lymphocytes. Reactive pneumocytes are especially common in organizing pneumonia and diffuse alveolar damage. The lung is the most common site of sarcoidosis, which […]

Respiratory infections

Cytology plays an important role in diagnosing infectious diseases in immunocompromised patients. Conventional inflammatory response may be much reduced, absent or greatly altered in these patients. Viral infections Bacterial infections Fungal infections Pneumocystis carinii Echinococcosis (hydatid disease)

Bacterial infections

Bacterial infections present as pneumonias or abscesses. Acute pneumonia and lung abscesses are characterized by a neutrophilic exudate. Many bacteria, but not all, can be seen with Routine stains as well as with Gram stain. A specific identification of Legionella pneumophila can be made in BAL samples by immunofluorescent antibody staining. Infection by Mycobacterium tuberculosis […]

Preneoplastic changes of respiratory epithelium

Squamous cell carcinoma of the lung is preceded by precursor lesions, with a progression from benign squamous metaplasia, through dysplasia, to invasive cancer. Most authors acknowledge degrees (mild, moderate, severe) of dysplasia. The risk of developing bronchogenic carcinoma increases with the degree of atypia. Preinvasive lesions Squamous dysplasia Carcinoma in situ Atypical adenomatous hyperplasia Diffuse […]

Lung cancer and other malignant tumours

Carcinoma of the lung is one of the most common malignancies in both men and women. It accounts for about 16% of all cancers diagnosed (20% of male and 12% of female cancers) making it the commonest malignancy and third most common cause of death in the UK. Its incidence has increased over the past […]

Viral infections

Herpes simplex thacheobronchitis and pneumonitis usually affect immunocompromised patients. Multinucleated cells are commonly seen, usually with eosinophilic, intranuclear inclusions. The dignosis can be confirmed by immunoperoxidase studies. Cytomegalovirus often causes an opportunistic infection, with diffuse pulmonary infiltrates. Viral changes, which are the same as in other sites, are seen in bronchial cells or pneumocytes: the […]

Reporting terminology

As with other non-gynaecologic cytologic specimens, respiratory tract diagnoses are reported as “negative for malignant cells”, “positive for malignant cells”, “suspicious for malignancy” (in this case a comment is required to state whether reactive or neoplastic changes are favoured) or “unsatisfactory (non-diagnostic)”, followed by a description.