Non-neoplastic conditions

In many benign disorders, effusions show a non-specific cytologic picture. However, some conditions are characterized by specific cytologic features which may be helpful in the differential diagnosis.

• Acute serositis
• Eosinophilic effusions
• Tuberculosis pleuritis
• Rheumatoid pleuritis
• Systemic lupus erithematosus (SLE)

Effusions due to pulmonary infarct

• Reactive mesothelial cells (often)
• Mitoses
• Haemosiderinophages
• Eosinophils (up to 60%)
• Lymphocytes and neutrophils