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Dr K K Aggarwal, President CMAAO
The Lancet Infectious Diseases, showed that the predominant pattern of lung lesions in patients with COVID-19 patients was diffuse alveolar damage.
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New Delhi, June 18, 2020 :
Luca Carsana, Papa Giovanni XXIII Hospital, Bergamo, Italy, and colleagues analysed lung tissue samples from 38 patients who died from COVID-19 in 2 hospitals in northern Italy between February 29, 2020, and March 24, 2020.
A median of 7 tissue blocks were taken from each lung, selecting the most representative areas identified at macroscopic examination. To better characterise the inflammatory infiltrate, immunohistochemical staining was done on the most representative areas of randomly selected cases for inflammatory infiltrate and cellular components, including staining with antibodies against CD68, CD3, CD45, CD61, TTF1, p40, and Ki-67.
Lungs of all patients were heavy, congested, and oedematous, with patchy involvement. In all cases, histological examination revealed features corresponding to the exudative and early or intermediate proliferative phases of diffuse alveolar damage, which included capillary congestion (in all cases), necrosis of pneumocytes (in all cases), hyaline membranes (in 33 cases), interstitial and intra-alveolar oedema (in 37 cases), type 2 pneumocyte hyperplasia (in all cases), squamous metaplasia with atypia (in 21 cases), and platelet-fibrin thrombi (in 33 cases).
Hyaline membrane formation and pneumocyte atypical hyperplasia are frequent. Importantly, the presence of platelet-fibrin thrombi in small arterial vessels is consistent with coagulopathy, which appears to be common in patients with COVID-19 and should be one of the main targets of therapy.
The patients had a mean age of 69 years and most (87%) were male. Time spent in the intensive care unit or intermediate medical ward ranged from 1 day to 23 days. At the time of hospitalisation, all patients had clinical and radiological features of interstitial pneumonia. Of the 26 patients with available D-dimer results, all had high values (>10 × the upper reference limit). Mean time from symptom onset to death was 16 days.
Reference: https://www.nejm.org/doi/full/10.1056/NEJMc2019373
SOURCE: The New England Journal of Medicine and The Lancet Infectious Diseases
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