Overview
Stable foci of Mycobacterium tuberculosis infection in the lungs after cure or spontaneous healing
Mostly asymptomatic
Formed after Mycobacterium tuberculosis infection is cured or resolves spontaneously.
Most do not require treatment, but some may need prophylactic treatment
Definition
Stale TB is a customary common name for inactive TB and is not standardized.
In the clinical practice of tuberculosis control, “old tuberculosis” on chest imaging is often regarded as the diagnosis of inactive tuberculosis.
The diagnosis of inactive tuberculosis can be made in the absence of clinical signs and symptoms associated with active tuberculosis, negative bacteriological examination, relatively stable tuberculosis-associated imaging changes (e.g., calcification, fibrosis, etc.), and the exclusion of other causes of imaging changes in the lungs.
Morbidity
There are few large-scale epidemiologic investigations of old TB, and the results are highly heterogeneous.
Nonetheless, it is generally recognized that the prevalence of old TB is related to the local TB epidemic, and that the incidence of TB in populations in areas with high TB prevalence is significantly higher than in areas with low TB prevalence.
The results of a study in China showed that among latent tuberculosis-infected individuals aged 50 to 70 years in rural areas of China, the risk of tuberculosis in people with old tuberculosis lesions on chest imaging was 6.77 times higher than that in people with normal imaging.
Causes
Causes
Old tuberculosis is caused by infection of the lungs with Mycobacterium tuberculosis (including cryptogenic infection), which is suppressed, killed, and turned to healing and then left behind as scarring.
Symptoms
Main symptoms
Mostly no obvious clinical symptoms.
Complications
A wide range of old tuberculosis may lead to chronic obstructive pulmonary disease (COPD) and manifest as recurrent coughing, sputum and symptoms such as chest tightness and shortness of breath, which in severe cases may further induce serious diseases such as pulmonary heart disease and respiratory failure, which will affect the patient’s quality of life and life expectancy.
Consultation
Department of Medicine
Department of Infectious Diseases
If old tuberculosis is detected during physical examination, it is recommended to consult a doctor promptly to determine whether tuberculosis is active.
Preparation for medical treatment
Preparation for consultation: registration, preparation of documents, common problems
Tips for medical treatment
Do not use anti-tuberculosis drugs without a doctor’s permission.
Preparation Checklist
Symptom list
Pay particular attention to the time of onset of symptoms, special manifestations, etc.
Are there any symptoms such as cough, sputum, chest tightness, shortness of breath, etc.?
Are there any symptoms such as low-grade fever, night sweats, hemoptysis, chest pain, etc.?
Medical history list
Is there a history of tuberculosis?
Are there any people in the surrounding population who have been diagnosed with TB?
Checklist
Test results of the last six months, which can be brought to the doctor’s office
Imaging tests: e.g. chest X-ray, chest CT, etc.
Laboratory tests: e.g. routine blood test, blood sedimentation, tuberculin test (PPD), etc.
Diagnosis
Diagnosis based on
Medical history
Possible past history of tuberculosis.
Clinical manifestations
Symptoms
Mostly no obvious clinical manifestations.
Chest imaging
This is the examination of choice for the diagnosis of old tuberculosis.
It mainly includes chest radiograph and chest CT, which is more sensitive than chest radiograph.
Imaging is consistent with one or more of the following and excludes other causes:
Calcified lesions (isolated or multiple);
Cordate lesions (well defined margins);
Sclerotic lesions;
Purulent cavities;
Pleural thickening, adhesions or with calcification.
Laboratory tests
Routine blood tests
Valuable in assessing the presence of secondary infection.
Elevated blood counts may be seen in the presence of secondary infection.
Blood sedimentation
Valuable in assessing the presence of tuberculosis activity.
Sedimentation tests are mostly normal in patients with old tuberculosis.
PPD, gamma-interferon release test, tuberculosis T-cell spot test, new tuberculin skin test (C-TST)
They can assess whether the patient has been infected with Mycobacterium tuberculosis, which is of significance in the diagnosis of old tuberculosis.
Positive results may be seen in patients with old TB.
Sputum search for antacid bacilli, sputum culture, Mycobacterium tuberculosis DNA test (TB-DNA)
can be used to assess the presence of TB activity and are valuable in the diagnosis of old TB.
Patients with old TB usually have negative results.
Diagnostic criteria
The diagnosis of old tuberculosis requires the fulfillment of 1 to 4 and any of 5 of the following criteria and the exclusion of other lung diseases.
History of tuberculosis
One of the following conditions is met:
No clear history of tuberculosis, but relatively stable tuberculosis-related imaging changes on chest imaging.
A history of relatively stable tuberculosis-associated imaging changes in the chest on chest imaging without or without standardized anti-tuberculosis treatment.
The patient exists a clear history of tuberculosis diagnosis and treatment to complete a regular course of anti-tuberculosis treatment, and treatment regression is judged as cure or completion of the course.
Clinical manifestations
There are no symptoms of suspected tuberculosis such as low-grade fever, night sweats, cough, sputum and chest pain.
Negative tuberculosis-related pathogenetic tests
Three sputum smears with antacid staining microscopy, mycobacterial culture and Mycobacterium tuberculosis nucleic acid test results were negative.
Meets diagnostic criteria for latent infection with Mycobacterium tuberculosis
PPD test hard nodule diameter of 5 mm or more in the absence of BCG vaccination and non-tuberculous mycobacterial interference.
PPD test hard nodule diameter of 10 mm or more in areas with BCG vaccination or non-Mycobacterium tuberculosis infection.
Mean PPD skin test nodule diameter of 5 mm or more in children ≤5 years of age who are HIV-positive or on immunosuppressive therapy for >1 month and who are not BCG-vaccinated and who have had close contact with a patient with active tuberculosis.
Positive new tuberculin skin test (C-TST).
Positive gamma-interferon release test.
Chest imaging
Has one or more imaging features of old tuberculosis.
Imaging features of pulmonary lesions: calcified lesions, fibrous lesions, sclerosing lesions, purging cavities, pulmonary sclerosis, etc.
Imaging features of pleural lesions: the presence of limited or extensive pleural thickening adhesions accompanied by different forms of calcification.
Imaging features of lymph node lesions: complete calcification or partial calcification of hilar and mediastinal lymph nodes.
Imaging features of bronchial lesions: bronchial lumen narrowing, smooth inner wall, or with mucosal calcification, complete absorption of lesions in the lung, fibrosis or sclerosis.
Differential diagnosis
Old tuberculosis should be differentiated from the following diseases.
Lung cancer
Similarities: both can lead to cavities in the lungs.
Differences:
Lung cancer is mostly seen in middle-aged and old-aged people with a long-term smoking history, and symptoms such as cough, sputum and hemoptysis may occur. The cavities formed in the lungs are mostly shown as eccentric thick-walled cavities on imaging, and tumor cells can be seen in sputum searching for exfoliated cells and pathological biopsy. Tuberculosis-related tests are mostly negative.
Old tuberculosis is common in patients with previous history of tuberculosis, most of them do not have any symptoms, and the cavities formed in the lungs are mostly characterized by thin-walled cavities with smooth inner walls and no contents on imaging. Check PPD, γ-interferon release test, tuberculosis T-cell spot test, new tuberculin skin test (C-TST) and other tests can be positive.
Lung abscess
Similarities: both can lead to lung cavities.
Differences:
Lung abscess occurs in the lower lobes of both lungs, and patients may present with recurrent fever, cough, and coughing up purulent sputum, etc. Liquid flatness is common in the cavities formed in the lungs, and tuberculosis-related tests are mostly negative and effective after antibiotic treatment.
Old tuberculosis occurs in the upper lungs, mostly without any symptoms, and the cavities formed in the lungs are mostly characterized by thin-walled cavities with smooth inner walls and no contents on imaging. Check PPD, γ-interferon release test, tuberculosis T-cell spot test, new tuberculin skin test (C-TST) and other tests can be positive and ineffective after antibiotic treatment.
Necrotizing granulomatous vasculitis
Similarities: both can lead to lung cavitation.
Points of difference:
Necrotizing granulomatous vasculitis may present as multiple foci in both lungs, but is more prevalent in the lower lobes of the lungs. Patients may present with cough, hemoptysis, and dyspnea, often accompanied by sinusitis and deepening of urine color.
The cavities formed by necrotizing granulomatous vasculitis in the lungs may be thin-walled or thick-walled, and are sometimes difficult to distinguish from those formed by old tuberculosis, but the tuberculosis-related tests are mostly negative, and the anti-neutrophil antibody profiles are mostly positive.
Old tuberculosis develops in the upper lungs and is mostly asymptomatic.
The cavities formed in the lungs by old tuberculosis are usually characterized by thin-walled cavities with smooth inner walls and no contents on imaging.PPD, gamma-interferon release test, tuberculosis T-cell spot test, and the new tuberculin skin test (C-TST) may be positive, and are ineffective after antibiotic treatment.
Active tuberculosis
Similarities: both can lead to lung cavities.
Differences: The presence or absence of TB-related symptoms such as low-grade fever, night sweats, cough, sputum, hemoptysis, chest pain, etc. and the negativity of TB-related pathogenicity tests such as sputum searching for antacid bacilli, sputum culture, and TB-DNA, etc. are the keys to differentiate the two.
Treatment
Treatment objective: to prevent the development of old tuberculosis into active tuberculosis.
Principles of treatment:
Assess the need for prophylactic treatment based on the specific condition.
Patients with a previous history of tuberculosis who have been treated with a standardized and adequate course of antituberculosis therapy for old tuberculosis do not need treatment.
Those who meet the diagnosis of old tuberculosis and have no previous anti-tuberculosis treatment or have irregular anti-tuberculosis treatment or insufficient course of treatment should undergo prophylactic treatment.
General treatment
Pay attention to rest, strengthen nutrition, avoid exertion and cold.
Drug treatment
Anti-tuberculosis drugs
Anti-tuberculosis drugs can inhibit or kill Mycobacterium tuberculosis.
Commonly used drugs include isoniazid, rifampicin, pyrazinamide, ethambutol and so on.
Drugs should be used under the guidance of a specialist, and changes in liver and kidney function should be detected during the use of drugs.
Prognosis
Cure
The overall prognosis of old TB is quite good and most of them will not affect the natural life expectancy, but some of them may have TB resurgence and develop into active TB.
Prognostic factors
Risk factors for the progression of old TB to active TB are associated with the following
History of tuberculosis
The risk of developing TB flare in old TB is associated with a previous history of TB disease.
People with a previous history of TB are at higher risk of developing active TB again.
Nature of the lesion
The risk of recurrence is increased when calcified lesions are >1.5 cm2.
People with fibrotic lesions have an increased risk of recurrence.
Immunity and environmental factors
The risk of recurrence of active tuberculosis is increased when the body’s immunity is reduced or when diseases affecting the immune system occur.
Environmental factors such as close contact with infectious TB patients and living in crowded, unventilated environments can lead to an increased risk of reinfection.
Daily
Daily Management
Dietary management
Eat a proper diet to ensure balanced nutrition to meet the body’s needs and enhance the body’s immunity.
Exercise
Participate in appropriate amount of sports activities to enhance your immunity.
Life management
Pay attention to rest, avoid staying up late, getting cold, getting wet, and other factors that can cause the body’s immunity to decline.
Disease monitoring
Attention should be paid to whether symptoms such as low-grade fever, night sweats, cough, sputum, hemoptysis, chest tightness, shortness of breath, chest pain, etc. occur, which suggests that tuberculosis recurrence, or complication of chronic obstructive pulmonary disease (COPD), secondary lung infections may be possible, and need to consult a doctor for follow-up in a timely manner.
Patients who use anti-tuberculosis drugs for prophylactic treatment should pay attention to the occurrence of itching, rash, jaundice and other adverse drug reactions.
Follow-up examination
Patients with old tuberculosis need to be followed up regularly, which helps the doctor to assess whether there is recurrence of tuberculosis or related complications.
The time of follow-up should be determined by the specialist according to the patient’s specific condition.
The main follow-up examinations are chest radiographs, chest CT and other imaging tests, as well as laboratory tests such as sputum search for bacilli, sputum culture and TB-DNA.
Prevention
Old tuberculosis is caused by infection with Mycobacterium tuberculosis, so prevention of Mycobacterium tuberculosis infection is the key to preventing the development of the disease.
Avoid TB-related contact
Avoid contact with TB patients or patients with a history of associated TB epidemics, especially sputum smear-positive patients.
BCG vaccination
Children should be immunized with BCG vaccine strictly according to medical advice.
Avoiding factors leading to decreased immunity
Avoid exertion, late night, cold, rain and other factors that may lead to immunity decline.
Actively treat underlying diseases such as diabetes, AIDS, malignant tumors, etc. that can lead to decreased immunity.
Enhance hygiene awareness
Enhance personal hygiene awareness in daily life and keep the living environment clean and tidy.