From the Guidelines
Pneumonia progresses through four distinct pathological stages, including early, progressive, peak, and absorption stages, as classified based on non-contrast enhanced chest computed tomography (CT) findings 1. The stages of pneumonia can be outlined as follows:
- Early stage (0-4 days): characterized by subpleural ground glass opacities (GGO) located in the lower lung lobes 1
- Progressive stage (5-8 days): demonstrates bilateral distribution of the infective process and diffuse GGO 1
- Peak stage (9-13 days): presence of dense consolidation, crazy-paving pattern, and residual parenchymal bands indicates transition into this stage 1
- Absorption stage (≥14 days): appears to demonstrate a better controlled disease process on CT, gradual resolution, and signs of recovery, which may last more than 26 days 1 Understanding these stages helps clinicians assess disease progression and response to treatment, with management typically involving appropriate antibiotics, supportive care, and monitoring for complications 1. Key features of each stage, such as the presence of ground glass opacities, consolidation, and parenchymal bands, can be identified through CT imaging, allowing for more accurate diagnosis and treatment planning 1.
From the Research
Pathological Stages of Pneumonia
The pathological stages of pneumonia can be categorized into several stages, including:
- Exposed stage: This stage is mentioned in the study 2 as one of the infection stages in infected individuals.
- Congestion stage: This stage is characterized by serous exudation with multiple cocci, as observed in 41% of cases in the study 3.
- Red hepatization stage: This stage is mentioned in the studies 3 and 4 as one of the histopathological patterns of lobar pneumonia, characterized by the presence of fibrin and neutrophils.
- Gray hepatization stage: This stage is mentioned in the study 3 as one of the histopathological patterns of lobar pneumonia, characterized by the presence of fibrin, neutrophils, and macrophages.
- Resolution stage: This stage is mentioned in the study 2 as one of the infection stages in infected individuals.
Histopathological Patterns
The histopathological patterns of pneumonia can be categorized into several types, including:
- Congestion or microbeous edema: This pattern is characterized by serous exudation with multiple cocci, as observed in 41% of cases in the study 3.
- Red hepatization: This pattern is characterized by the presence of fibrin and neutrophils, as mentioned in the studies 3 and 4.
- Gray hepatization: This pattern is characterized by the presence of fibrin, neutrophils, and macrophages, as mentioned in the study 3.
CT Manifestations
The CT manifestations of pneumonia can vary depending on the stage of the disease, including:
- Early stage: Scattered flaky ground glass opacities (GGOs) in various sizes, dominated by peripheral pulmonary zone/subpleural distributions, as mentioned in the study 5.
- Progression stage: GGOs increase in number and/or size, and lung consolidations may become visible, as mentioned in the study 5.
- Absorption stage: Interstitial change of both lungs, such as fibrous cords and reticular opacities, as mentioned in the study 5.