Volume 15 Issue 02, February 2025
Impact factor: 2019: 4.679 2020: 5.015 2021: 5.436, 2022: 5.242, 2023:
6.995, 2024 7.75
http://www.internationaljournal.co.in/index.php/jasass
151
MORPHOLOGICAL AND PATHOLOGICAL CHANGES IN THE LUNGS DUE TO
COVID-19
Scientific Advisor
: Xolieva Nigora Khudayberdievna
Mahkamova Mohbegim Aziz kizi
Abdullayev Baxtiyor Abdumannop o'g'li
Rakhmatullayeva Sabrina Kamolovna
Students of Tashkent Medical Academy
Abstract:
The COVID-19 pandemic has significantly impacted not only global healthcare
systems but also the human div. The SARS-CoV-2 virus damages both the upper and lower
respiratory tracts, leading to severe inflammatory processes in the lungs. The acute and chronic
phases of this disease can cause serious pathological conditions such as alveolar damage,
microthrombosis, and fibrosis.
This article provides a comprehensive review of the morphological and pathological changes in
the lungs due to COVID-19, explaining how the virus affects alveolar cells, triggers
inflammatory processes, and leads to long-term complications.
Keywords:
COVID-19, SARS-CoV-2, lung pathology, alveolar damage, fibrosis, thrombosis,
cytokine storm, microthrombosis, diffuse alveolar damage (DAD), pulmonary fibrosis.
Main Section
Mechanism of COVID-19 Entry and Damage to the Lungs
COVID-19 is transmitted through airborne droplets and reaches the lungs via the upper
respiratory tract. The virus binds to ACE2 receptors and primarily infects alveolar epithelial cells.
This process occurs in the following stages:
1. Entry of the Virus into Alveolar Cells
The S-spike protein of the SARS-CoV-2 virus binds to type II pneumocytes in the alveoli.The
virus enters the cells, replicates its RNA, and destroys them.
2. Immune Response and Inflammation
Cytokines (IL-6, IL-1β, TNF-α) released by infected cells initiate an inflammatory
response.Neutrophils and macrophages migrate to the alveoli to eliminate the pathogens.
3. Microthrombosis and Vascular Damage
The inflammatory process damages endothelial cells, leading to thrombosis. This disrupts blood
circulation in the alveoli, causing hypoxemia and respiratory failure.
Volume 15 Issue 02, February 2025
Impact factor: 2019: 4.679 2020: 5.015 2021: 5.436, 2022: 5.242, 2023:
6.995, 2024 7.75
http://www.internationaljournal.co.in/index.php/jasass
152
4. Pulmonary Fibrosis and Long-Term Damage
After the acute inflammation phase, fibroblasts become activated in the alveoli. The
accumulation of connective tissue leads to pulmonary fibrosis, resulting in long-term breathing
difficulties.
Morphological Changes in the Lungs Due to COVID-19
COVID-19 induces various pathological processes in lung tissue. The most significant ones
include:
1. Diffuse Alveolar Damage (DAD)
DAD is one of the main pathological features of COVID-19 pneumonia. It progresses in three
phases:
Exudative Phase=> Severe inflammation and fluid accumulation in the lungs. Damage to
alveolar walls, formation of hyaline membranes.Patients experience severe respiratory distress.
Proliferative Phase=> Activation of fibroblasts leads to the regeneration of cells. Thickening of
alveolar walls but loss of elasticity.
Fibrotic Phase=> Pulmonary fibrosis develops due to excess connective tissue. This impairs lung
function, causing long-term complications.
2. Microthrombosis and Circulatory Disorders
In 30-50% of COVID-19 patients, thrombi are found in pulmonary capillaries.
Consequences include:
Pulmonary embolism: Thrombi obstruct large arteries, leading to acute respiratory failure.
Impaired gas exchange: Oxygen deficiency occurs.
Pulmonary hypertension: Increased vascular pressure puts strain on the right side of the heart.
3. Cytokine Storm and Alveolar Inflammation
One of the most dangerous mechanisms of COVID-19 is the cytokine storm. The immune
system overreacts, producing excessive inflammatory mediators (IL-6, IL-1β, TNF-α).
Uncontrolled inflammation damages the alveoli. Patients deteriorate rapidly, often requiring
mechanical ventilation.
Long-Term Effects of COVID-19 on the Lungs
The long-term consequences of COVID-19 pneumonia include:
Volume 15 Issue 02, February 2025
Impact factor: 2019: 4.679 2020: 5.015 2021: 5.436, 2022: 5.242, 2023:
6.995, 2024 7.75
http://www.internationaljournal.co.in/index.php/jasass
153
1. Pulmonary Fibrosis: Loss of elastic tissue disrupts normal lung function.
2. Chronic Respiratory Failure: Alveolar dysfunction causes persistent shortness of breath.
3. Post-COVID Syndrome: Patients may suffer from prolonged fatigue, breathing difficulties,
and cardiovascular issues.
Pathological Features and Clinical Manifestations
The pathological changes in the lungs due to COVID-19 can manifest in various clinical forms.
The main symptoms include:
Acute Respiratory Failure: Impaired oxygen exchange due to alveolar tissue damage.
Hypoxemia: Reduced oxygen levels in the blood due to impaired gas exchange.
Pulmonary Fibrosis: Long-term COVID-19 pneumonia leads to scarring of lung tissue,
restricting lung capacity.
Hemorrhagic Pneumonia: Bleeding in the alveoli and rupture of small blood vessels may occur.
Volume 15 Issue 02, February 2025
Impact factor: 2019: 4.679 2020: 5.015 2021: 5.436, 2022: 5.242, 2023:
6.995, 2024 7.75
http://www.internationaljournal.co.in/index.php/jasass
154
Lethal Pulmonary Pathology in COVID-19
1. Early Lung Damage: Alveolar edema, endothelial necrosis, microthrombosis, and
endothelialitis.Progressive inflammatory vascular damage with nuclear debris and granulocytes.
2. Exudative Phase of DAD: Hyperplasia of type II pneumocytes.
3. Formation of Giant Intra-Alveolar Cells: Observed in the exudative phase of DAD.
4. Hyaline Membranes and Fibrin Deposits: Present in the exudative phase of DAD.
5. Thrombosis in Small and Medium-Sized Vessels: Occurs in the early stages of lung disease.
6. Invasive Aspergillosis: A rare form of superinfection in the late phase of DAD.
7. Organizing Phase of DAD: Loose connective tissue fibrosis in interstitial and intramural
spaces. Intra-alveolar plugs.
Volume 15 Issue 02, February 2025
Impact factor: 2019: 4.679 2020: 5.015 2021: 5.436, 2022: 5.242, 2023:
6.995, 2024 7.75
http://www.internationaljournal.co.in/index.php/jasass
155
8. Late Phase of DAD Organization: Massive bronchopulmonary squamous metaplasia.
Conclusion
COVID-19 infection causes complex morphological and pathological changes in lung tissue.
Processes such as diffuse alveolar damage, capillary thrombosis, and pulmonary fibrosis
contribute to the severity of the disease. Early diagnosis, intensive treatment, and rehabilitation
are crucial in minimizing long-term complications of COVID-19 pneumonia. Treatment
strategies should focus on antiviral drugs, immunomodulators, and pulmonary rehabilitation.
References
1. Zhu, N., Zhang, D., Wang, W., et al. (2020). A novel coronavirus from patients with
pneumonia in China, 2019. The New England Journal of Medicine, 382(8), 727-733.
2. Carsana, L., Sonzogni, A., Nasr, A., et al. (2020). Pulmonary post-mortem findings in a large
series of COVID-19 cases from Northern Italy. The Lancet Infectious Diseases, 20(10), 1135-
1140.
3. Ackermann, M., Verleden, S. E., Kuehnel, M., et al. (2020). Pulmonary vascular
endothelialitis, thrombosis, and angiogenesis in COVID-19. The New England Journal of
Medicine, 383(2), 120-128.
4. Xu, Z., Shi, L., Wang, Y., et al. (2020). Pathological findings of COVID-19 associated with
acute respiratory distress syndrome. The Lancet Respiratory Medicine, 8(4), 420-422.
5. Varga, Z., Flammer, A. J., Steiger, P., et al. (2020). Endothelial cell infection and endotheliitis
in COVID-19. The Lancet, 395(10234), 1417-1418.
