Pathological anatomy of vascular lesions in influenza and viral-bacterial pneumonia

Pathological anatomy of vascular lesions in influenza and viral-bacterial pneumonia

I.V. Dvorakovskaya¹, O.N. Titova¹, B.M. Ariel², I.S. Platonova¹, V.A. Volchkov³, N.A. Kuzubova¹

¹Research Institute of Pulmonology of the I.P. Pavlov First Saint Petersburg State Medical University, Saint Petersburg

²St. Petersburg Research Institute of Phthisiopulmonology, Saint Petersburg

³St. Petersburg State University, Saint Petersburg

Aim: to evaluate the structural changes of vessels in influenza and viral-bacterial pneumonia, and their role in thanatogenesis.

Patients and Methods: 387 autopsy reports were analyzed in St. Petersburg hospitals in 2016, and clinical diagnoses were compared with anatomicopathological or forensic diagnoses to determine the underlying disease and its complications. Most of the deceased (64.3% of the total number) were male patients. Microscopic examination of lung preparations and other organs stained with hematoxylin and eosin, as well as immunohistochemistry of influenza A virus nucleoproteins expression in alveolocytes and macrophages were performed.

Results: presenile age plays a key role in thanatogenesis, since the maximum mortality was observed in the age group of 60–79 years (42.2%), while the minimum mortality — in the group of 20–39 years (11.9%). The main cause of fatal outcome was severe pneumonia, the exact etiology of which was not established, since bacterioscopic and bacteriological studies were not conducted. Microscopic examination revealed hemorrhagic and necrotic and deep fibrinous-ulcerative lesions of the tracheal and bronchial mucosa, as well as exudative necrotic processes in the pulmonary parenchyma, peribronchitis and acute destructive bronchiectasis. These were combined with dystrophic and necrobiotic changes in the vascular wall, its permeability disorder, hyperemia, stasis, thrombosis and hemorrhages characteristic of vasculitis. The severity degree of morphological manifestations concerning vascular pathology (as essential patterns of influenza and combined influenza bacterial infection) varied significantly depending on the disease duration and the severity of secondary bacterial infection.

Conclusions: the combination of inflammatory changes in the lungs with circulatory disorders in influenza and viral-bacterial pneumonia creates a detailed picture of the black lung. Bacterial flora activation by the type of autoinfection in the setting of depressed immunity in influenza, along with severe inflammation to vessels and pulmonary parenchyma, plays a leading role in thanatogenesis.

Keywords: influenza, pneumonia, autoinfection, bronchitis, alveolitis, vasculitis, circulatory disorders, underlying disease, complication, thanatogenesis.

For citation: Dvorakovskaya I.V., Titova O.N., Ariel B.M. et al. Pathological anatomy of vascular lesions in influenza and viral-bacterial pneumonia. RMJ. 2021;3:3–7.