Neutrophilic infiltration in purulent meningitis
A classical example of pronounced leukocytic infiltration is purulent meningococcal meningitis. It is characterized by massive neutrophilic infiltration, which becomes a key diagnostic criterion when examining cerebrospinal fluid (CSF).
The main CSF changes include:
- Macroscopic picture: the cerebrospinal fluid becomes turbid, acquires a whitish or yellow-green tint, and flows out under increased pressure.
- Cytology: marked neutrophilic pleocytosis develops (500–1000 cells or more per 1 µl, with 60–100% being neutrophils). In severe cases, the cell count can reach 4- to 5-digit figures.
- Biochemistry: cellular-protein dissociation is observed — the protein level rises to 2–8 g/L, lactate concentration increases while glucose decreases simultaneously.
- Bacterioscopy: Gram-negative diplococci are visualized, which can be located both extracellularly and intracellularly (inside the neutrophils themselves).
In peripheral blood (hemogram), this process is accompanied by neutrophilic leukocytosis with a left shift of the leukocyte formula, thrombocytopenia, and elevated ESR. In cases of meningococcemia, neutrophilic hyperleukocytosis with a marked left shift is observed.
Infiltration in endometrial and intestinal pathologies
Leukocytic infiltration serves as an important morphological sign not only in classic inflammation, but also in hyperplastic processes.
In the endometrium: In simple (glandular or glandular-cystic) endometrial hyperplasia, there is an increase in the number of glands and a change in their shape. The stroma in this form of lesion is rich in fibroblasts and contains a relatively large number of lymphoid elements. Marked infiltration by lymphocytes and neutrophils is characteristic, accompanied by vascular congestion and the presence of thrombi within them. The process predominantly affects the functional layer of the mucous membrane, without division into compact and spongy layers.
In the gastrointestinal tract: In abdominal forms of a number of infectious diseases (for example, in catarrhal or catarrhal-ulcerative gastroenteritis, gastroenterocolitis, terminal ileitis), hyperplasia and ulceration of the intestinal lymphoid apparatus (Peyer's patches) are observed. In these cases, the intestinal wall is actively infiltrated by a polymorphic cellular composition, including neutrophils, lymphocytes, eosinophils, and plasma cells.
The Role of Infiltration in Heart Failure
In the myocardium, the appearance of a leukocyte infiltrate often indicates the development of decompensation against the background of long-standing pathologies.
In chronic diastolic heart failure, compensatory myocardial hypertrophy begins to combine with diffuse fibrosis and cellular (leukocyte) infiltration of the stroma. This morphological triad (cardiomyocyte hypertrophy, connective tissue proliferation, and inflammatory cell infiltration) leads to a decrease in ventricular wall compliance and, consequently, to a pathological increase in left ventricular end-diastolic pressure.
Class and exam questions
Which cells predominate in the cerebrospinal fluid in meningococcal meningitis?
Neutrophils predominate in the cerebrospinal fluid. Marked neutrophilic pleocytosis develops (500–1000 cells per 1 µL), with neutrophils accounting for 60–100%.
How does true meningitis differ from meningism in terms of cerebrospinal fluid composition?
In meningism, signs of inflammatory infiltration in the cerebrospinal fluid are absent. Macroscopy, biochemistry, and the cytogram remain normal; only a slight increase in cell count is permitted without massive leukocyte infiltration.
Which cells form the infiltrate in the intestinal wall during abdominal infections?
In abdominal forms of infections (for example, in terminal ileitis), the intestinal wall is infiltrated by neutrophils, lymphocytes, eosinophils, and plasma cells.
What else to study on this topic
- Protein-cytologic dissociation of cerebrospinal fluid in meningitis
- Differences between simple and complex endometrial hyperplasia
- Ultrastructural changes in cardiomyocytes during hypertrophy
- Reactive lymph node hyperplasia
- Differential diagnosis of purulent meningitis
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