Ground-glass miliary or nodular changes in both lungs

Introduction In patients with cytomegalovirus pneumonia, chest X-ray and CT are commonly seen in both glassy miliary or nodular changes. Cytomegalovirus (CMV) is a viral pneumonia characterized by the formation of large type A eosinophilic intranuclear and intracytoplasmic inclusions in infected cells. Most are asymptomatic latent infections, but can cause severe lung infections in infants with low immune function and death. In recent years, with the development of bone marrow and organ transplantation and the increasing number of AIDS patients, CMV has become the most common pathogen in these two cases.

Cause

(1) Causes of the disease

The cytomegalovirus belongs to the group B herpesvirus and is a double-stranded DNA virus with an outer envelope and a nucleus. Poor stability to heat and low temperature, inactivated at 56 ° C for 30 min or 4 ° C for 1 week, can also be inactivated by UV and fat-soluble solvents. CMV has two antigens, complement-binding antigen and neutralizing antigen. The former exists mostly as a soluble antigen, and the latter is mainly composed of glycoprotein, which is one of the components of the viral envelope. CMV infection has strict species specificity, humans are only infected by human cytomegalovirus, and the infected virus slowly grows and multiplies in the cells (2 to 3 months showing obvious lesions). The infected nuclei are enlarged, and the cytoplasm is increased to form a typical eosinophilic nucleus and cytoplasmic inclusion bodies.

(two) pathogenesis

CMV can be transmitted in a variety of ways, infants and young children are mainly sexually transmitted, and adults are mainly sexually transmitted. The extent of the infection after infection depends on the amount of virus contacted and the immune status of the body. CMV mainly infects a variety of immune-active cells including vascular endothelial cells, T cells, B cells, and NK cells distributed in epithelial cells and mesentery. After infection, it replicates in vivo, and the volume of infected cells increases. Focal necrosis and release of newly synthesized virus further infects surrounding cells. The cells infected with lung tissue are mainly alveolar cells and macrophages. After infection, diffuse pulmonary interstitial edema, fibrosis and alveolar swelling, focal necrosis, hemorrhage and hyperplasia, resulting in hypoxemia. Since cellular immunity plays a major role in anti-CMV infection, the condition of CMV infection in patients with cellular immunodeficiency (such as bone marrow transplantation and AIDS patients) is particularly serious.

an examination

Related inspection

Pulmonary function test lung biopsy lung imaging

Because of the similarity in the clinical manifestations of viral pneumonia, pathogenic examination is particularly important. The pathogen examination of CMV can be carried out in the following ways:

1 Detection of CMV inclusion body cells and virus particles: if isolated from patients' blood, urine, and bronchial lavage, but there is a high false positive, 71% to 91% of high-risk transplant patients from CAL, although CMV is isolated, But there is no evidence of active pneumonia. The patient's various secretion samples may also be inoculated in vitro in human embryos or fibroblasts for isolation and detection, but it usually takes 2 weeks to 2 months to confirm the diagnosis;

2 Immunological methods: CMV antigens in patients and donor secretions can be measured by fluorescent or enzyme-labeled antibodies, which facilitate early diagnosis and screening of donors before transplantation. The antibodies in serum can also be dynamically detected by complement binding assay, and the serum antibody titers in the acute phase and the recovery phase are more than 4 times positive;

3 molecular biological methods: such as PCR technology and nucleic acid hybridization, the former is mainly used for the detection and dynamic monitoring of BAL, the latter is often used for the detection of pathological sections of lung tissue, and can distinguish between different subtypes of viruses. .

Differential diagnosis

Should be distinguished from other diseases: such as other viral pneumonia (respiratory syncytial virus, influenza, parainfluenza or enterovirus), Pneumocystis carinii and Chlamydia lung infection.

Most of the CMV-infected patients with good immunity are asymptomatic and concealed, and thus become the source of infection of CMV infection in bone marrow and organ transplant recipients. Therefore, it is important to perform a CMV serological examination of the donor prior to transplantation. There are two clinical manifestations of cytomegalovirus pneumonia after transplantation:

1. Rapid advancement: fever, cough, discomfort, dyspnea, decreased mobility, hypoxia and respiratory failure occur 1 to 2 months after transplantation; pulmonary auscultation has no signs, and can be detected by bacterial or fungal infections? The disease progresses rapidly and can rapidly deteriorate and die; the X-ray of the lung is mainly characterized by multiple miliary nodules in both lungs with a diameter of 2 to 4 mm; the autopsy pathology shows diffuse alveolar hemorrhage, fibrosis and neutrophil response. Common in the primary infection, no specific antibodies in the body, so the incidence is acute, heavy, easily lead to systemic viremia and secondary bacterial and fungal infections.

2. Slow-moving type: 3 to 4 months after transplantation, the symptoms are similar to the rapid progression, but the progress is slow, the symptoms are mild, the mortality is low; the lung X-ray shows diffuse interstitial pneumonia, fibrosis; pathological manifestations For alveolar interstitial edema, varying degrees of fibrosis, lymphocytic infiltration and epithelial cell hyperplasia. Commonly caused by CMV reinfection or latent viral activation.

CMV pneumonia in AIDS patients is not specific, often associated with systemic CMV infections such as retinitis, colitis, cholangitis, and esophagitis. Chest radiography and CT often have two lungs with glassy, miliary or nodular changes. Blood routines suggest a decrease in surrounding white blood cells.

Because of the similarity in the clinical manifestations of viral pneumonia, pathogenic examination is particularly important. The pathogen examination of CMV can be carried out in the following ways:

1 Detection of CMV inclusion body cells and virus particles: if isolated from patients' blood, urine, and bronchial lavage, but there is a high false positive, 71% to 91% of high-risk transplant patients from CAL, although CMV is isolated, But there is no evidence of active pneumonia. The patient's various secretion samples may also be inoculated in vitro in human embryos or fibroblasts for isolation and detection, but it usually takes 2 weeks to 2 months to confirm the diagnosis;

2 Immunological methods: CMV antigens in patients and donor secretions can be measured by fluorescent or enzyme-labeled antibodies, which facilitate early diagnosis and screening of donors before transplantation. The antibodies in serum can also be dynamically detected by complement binding assay, and the serum antibody titers in the acute phase and the recovery phase are more than 4 times positive;

3 molecular biological methods: such as PCR technology and nucleic acid hybridization, the former is mainly used for the detection and dynamic monitoring of BAL, the latter is often used for the detection of pathological sections of lung tissue, and can distinguish between different subtypes of viruses. .

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