The role of cytopathology in the early diagnosis of malignancies
When a physician suspects the presence of cancerous disease, he or she may request a cytological examination: an analysis of cells isolated or in small groups, taken from body fluids (such as urine, pleural fluid) or from lesions by needle aspiration. Once collected, these cells are fixed on slides and sent to the anatomic pathology laboratory.
And that is where the pathologist comes in, who, by observing slides under a microscope, plays an essential role in the early identification of cancerous pathologies.
And that is where the pathologist comes in, who, by observing slides under a microscope, plays an essential role in the early identification of cancerous pathologies.
What does the pathologist look for on cytology slides?
Cytological examination is based ondirect observation of cells. Unlike histology (which analyzes tissue), cytology assesses cell morphology, offering a rapid and often crucial first response to guide the diagnostic or therapeutic course.
Here are the main features that the pathologist observes:
1. Presence of abnormal cells: The first step is to assess whether the cells on the slide are normal, reactive (i.e., modified by inflammation or noncancerous lesions) or atypical or frankly neoplastic. Cancer cells are distinguished by specific morphological changes.
2. Nuclear features: The cell nucleus is often the first indication of abnormality. The pathologist evaluates:
- Increased nucleus/cytoplasm ratio: nuclei are large relative to the volume of the cell.
- Irregularity of nuclear contour: nuclei not round, with irregular margins.
- Hyperchromasia: dark nuclei due to increased DNA content.
- Presence of prominent nucleoli: a sign of replicative activity.
- Mitosis: cell divisions, especially if atypical or numerous.
These indices help determine whether cells are suspicious or malignant.
3. Cellular architecture (when present): Although no actual tissue is observed in cytology, the pathologist assesses any cellular groupings:
- Papillae, three-dimensional aggregates, single isolated cells.
- Cell cohesion, typical in some tumors (e.g., small cell carcinoma).
These aspects help suggest tumor type (adenocarcinoma, squamous cell carcinoma, urothelial carcinoma, etc.).
4. Cellular context: The pathologist also observes the "background" of the slide:
- Blood, necrosis, inflammatory cells may accompany neoplastic cells.
- The presence of reactive mesothelial cells or inflammatory cells may help in the differential diagnosis.
2. Nuclear features: The cell nucleus is often the first indication of abnormality. The pathologist evaluates:
- Increased nucleus/cytoplasm ratio: nuclei are large relative to the volume of the cell.
- Irregularity of nuclear contour: nuclei not round, with irregular margins.
- Hyperchromasia: dark nuclei due to increased DNA content.
- Presence of prominent nucleoli: a sign of replicative activity.
- Mitosis: cell divisions, especially if atypical or numerous.
These indices help determine whether cells are suspicious or malignant.
3. Cellular architecture (when present): Although no actual tissue is observed in cytology, the pathologist assesses any cellular groupings:
- Papillae, three-dimensional aggregates, single isolated cells.
- Cell cohesion, typical in some tumors (e.g., small cell carcinoma).
These aspects help suggest tumor type (adenocarcinoma, squamous cell carcinoma, urothelial carcinoma, etc.).
4. Cellular context: The pathologist also observes the "background" of the slide:
- Blood, necrosis, inflammatory cells may accompany neoplastic cells.
- The presence of reactive mesothelial cells or inflammatory cells may help in the differential diagnosis.
Conclusion
By analyzing a few cells on a slide, the pathologist can give a quick and reliable diagnosis, directing an early course of treatment. Thanks to increasingly sophisticated technologies, including advanced staining, immunocytochemistry, and artificial intelligence, cytopathology is now a powerful and precise tool in the fight against cancer.
