The role of cytology in the diagnosis of local inflammation
Assessment of cellular composition plays a key role in analyzing effusions and purulent discharge. For example, when acute purulent inflammation of a synovial bursa (bursitis) is suspected, a puncture with aspiration of the exudate is performed. Subsequent cytological and bacteriological examination of the pus is necessary to identify specific pathogens (gonococcus, Brucella) and choose treatment tactics.
In dentistry, laboratory assessment of smears and punctates is performed strictly according to indications. The study of oral fluid, pathological exudate, and scrapings is used for the differential diagnosis of oral mucosa diseases, periodontal disease, salivary gland lesions, and the verification of tumors.
In deep corneal inflammations (keratitis) accompanied by purulent ulcers, cellular infiltration naturally spreads to the iris and ciliary body. As a result, hypopyon—an accumulation of purulent exudate—forms in the anterior chamber of the eye. To make an accurate diagnosis, a complex of laboratory methods is used: microscopic examination of the smear, bacteriological culture, and specific cytological examination of conjunctival scrapings.
Cellular reactions in lymph nodes
The peripheral lymphoid system (including tonsils, Peyer's patches, spleen, and lymph nodes) acts as the main staging ground for the cellular inflammatory response. Structural changes in these organs directly reflect the nature of the impaired immune response.
In acute reactive lymphadenitis, the node parenchyma is heavily infiltrated with serous exudate, and the tissue loosens. Edema blocks the outflow of peripheral lymph, creating ideal conditions for a massive accumulation of lymphocytes and phagocytes. The organ implements its barrier function by sequestering pathogens.
The transition of inflammation to a chronic stage is accompanied by hyperplasia of lymphoid elements. Gradually, they die off, the capsule thickens, and specific cells are replaced by fibrous connective tissue.
Reactive changes in cellular composition (lymphadenopathies) develop according to several scenarios:
- Hyperplasia of benign lymphocytes in specific zones.
- Sinus histiocytosis (a sharp increase in the number of macrophages).
- Massive tissue infiltration by inflammatory cells during infectious aggression.
- Accumulation of macrophages overloaded with metabolic products.
- Malignant cell proliferation in situ.
Cytological picture in viral and systemic lesions
Normally, lymphoid tissue has a clear division into T-zones (paracortical area) and B-zones (follicles and germinal centers). Selective cytological lesion of one of the zones corresponds to a specific immune defect.
The most studied model of cellular transformation is lymph node involvement in HIV infection. At the first stage of the process (follicular hyperplasia), cytological and histological analysis reveals characteristic features:
- Light centers of follicles are filled with macrophages and large cells with signs of active division (mitotic figures).
- The paracortical area is heavily infiltrated with immunoblasts with high mitotic activity.
- Sinus lumens are expanded, accumulating neutrophils and large mononuclear macrophages.
- At the final stage of this phase, desquamated endothelium and multinucleated giant cells (symplasts), morphologically similar to those appearing in measles, are identified.
In other pathologies, such as sarcoidosis, immunological shifts (decreased T-lymphocyte count, polyclonal B-cell activation) are accompanied by the formation of specific granulomas. To precisely confirm the nature of the cellular shift, cytological examination of a lymph node punctate remains an irreplaceable method.
To memorize the composition of cells in the sinus lumens during viral lymph node hyperplasia, use the acronym MENS: Macrophages, Endothelium (desquamated), Neutrophils, Symplasts (multinucleated cells).
Class and exam questions
Why is a cytological examination performed when purulent bursitis is suspected?
Analysis of the purulent exudate obtained from bursa puncture makes it possible to assess the nature of the cellular infiltrate and identify specific microorganisms (e.g., gonococcus).
How does a lymph node change in the acute stage of inflammation?
Serous exudate accumulates in the parenchyma. Due to the cessation of lymph drainage, a massive accumulation of lymphocytes and phagocytes forms in the node to ensure the barrier function.
What specific cells are identified in the lymph node sinuses at the initial stage of HIV infection?
Clusters of neutrophils, macrophages, desquamated endothelium, as well as characteristic multinucleated giant cells—symplasts—are detected.
What else to study on this topic
- Morphological characteristics of the stages of lymphoid tissue depletion in immunodeficiencies.
- Differential diagnosis of inflammatory periodontal diseases (gingivitis and periodontitis).
- Associated reactions of the vascular tunic of the eye in deep keratitis.
- Outcomes of keratitis and mechanisms of compensatory corneal vascularization.
- Oral hygiene indices and markers of oral mucosal inflammation.
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