Tuberculosis Series: Physical Manifestations of TB Infection
Author(s): Miranda S. Bradley, MD; Carey Jackson, MD
Date Authored: March 7, 2020
Primary tuberculosis infection occurs when someone who has never been exposed to the Mycobacterium tuberculosis pathogen is initially exposed. In most developing areas of the world, this occurs during childhood, and typically manifests with respiratory symptoms and fever. For individuals with a healthy immune system, the infection can be cleared and the bacteria no longer replicate in the host. If the person is unable to completely clear the infection the bacteria can enter a latent phase, only to reactivate aggressively if the person experiences a period of immunocompromise in their life.
In primary TB presenting with respiratory symptoms, a chest radiograph (CXR) will most commonly show no abnormalities, although hilar adenopathy and pleural effusions may be seen, common pulmonary lesions are shown below.
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Primary TB in the Lung
Reactivation Pulmonary Lesions
If a patient was unable to completely clear their primary infection, the bacteria may lie dormant in the lungs only to reactivate when the person experiences a period of immunocompromise. Cavitary lesions are the most commonly discussed pathology associated with latent TB infection.
Healed tuberculosis is characterized also by specific lesions as well as apical pleural thickening, fibrosis and volume loss. As the lung scars from the recent infection, patients may report consistent and unrelenting shortness of breath and cough. Patients with these permanent lung changes would also be at increased risk for pulmonary infections due to the potential spaces to house bacteria.
HIV & TB
Patients with HIV and TB coinfection have altered manifestations of disease. Even in LTBI a more-primary pattern may be visible on CXR. Adenopathy is common, but in around 10% of cases the CXR may be normal.
Extrapulmonary Tuberculosis Infection
Extrapulmonary tuberculosis and pulmonary tuberculosis most commonly appear together. As the signs of pulmonary tuberculosis can be difficult to identify in areas of the world where a CXR would be difficult to acquire, the manifestations of extrapulmonary tuberculosis are important to detect as obvious indications of the systemic disease. Once tuberculosis involves the lymph system a person becomes a risk of developing Pott Disease, which is the hematologic spread of tuberculosis to all areas of the body, most commonly the spine.
Images below used with permission for the International Union Against Tuberculosis and Lung Disease.
Lymphatic tuberculosis occurs in approximately 42% of patients diagnosed with extrapulmonary tuberculosis in the United States. More common in women and children, this form of TB typically involves painless swelling of one or many lymph nodes around the neck. As the disease progresses, the enlarged lymph node can cause overlying skin irritation or compression of surrounding structures (like the esophagus). Lymph node biopsy or aspiration of cells is required for diagnosis and lymph nodes are much slower to respond to the traditional RIPE treatment than pulmonary infection.
While peripheral lymphatic tuberculosis is most frequently found around the neck, the axilla is also sometimes involved. Several lymph nodes may be matted together, as in this patient (below). Some nodes have undergone liquefaction necrosis leading to the discolored appearance of the skin.
Hopewell PC, Kato-Maeda M, Ernst JD. Tuberculosis. In: Murray and Nadel’s Textbook of Respiratory Medicine. 6th ed. Philadelphia, PA: Elsevier, Inc.; 2016:593-628.
As the disease process of tuberculosis progresses, a person is more likely to develop bone involvement associated with Pott Disease. Spread from infected lymph nodes can lead to seeding of bone after the initial infection. New onset bone pain or skin lesions may be the presenting sign, and a thorough evaluation is required so as not to miss the important diagnosis. TB is more likely to initially involve the metaphysis of long bones and will eventually progress to involve cartilage, synovium and joint space.
Spinal TB is most frequently located in the lower thoracic and the lumber region of the spine. It can result in weakened vertebrae and lead to spine decay. A gibbus may form after vertebrae collapse into a wedge shape resulting in visible kyphosis.
Chen WJ, et al. Acta Orthop Scand 1995; 66:137-142
Initially, neurologic symptoms may be seen due to edema and compression caused by abscess surrounding the spinal cord. This will resolve with chemotherapy, and ultimately the only permanent damage is seen on the anterior vertebrae. The reason for complete recovery from neurologic symptoms in the majority of patients is most likely attributable to the anterior location of the lesion that often spare the spinal canal. Weakened vertebrae predispose patients to fracture. Additionally, in some patients, bone particles that have broken off may eventually reach the spinal canal which could ultimately lead to permanent disability.
Tuberculosis of the Joint
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