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.

Click on images below to see them larger.

Primary TB in the Lung

Lobar consolidation of the right upper lung.
Lobar consolidation of the right upper lung
Miliary pattern is the most common manifestation.
Miliary pattern is the most common manifestation
Adenopathy of Hila and Mediastinum
Adenopathy of Hila and Mediastinum is most common in children and immunocompromised patients, typically found on the right side
Example of Pleural Effusion.
Pleural effusions are seen most often in adults.
Example of Pleural Effusion
A new pleural effusion may be the first indication of tuberculous disease and requires sampling to determine pathogen.
Example of Pleural Effusion
Pleural effusion

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.  

Lung Parenchyma involvement in initial TB infection leads to fibrosis and scarring. Right side most commonly affected
Consolidation – Typically found in apical/posterior segments of the upper lobes and superior segments of the lower lobes
Cavitary lesions on the left side
Cavitary nodule
Evidence of endobronchial spread of infection
Miliary pattern found in LTBI
Tuberculoma
While pleural effusions are common manifestations of active tuberculosis infection, an empyema is more common after the primary infection
If an air-fluid level is seen, may be bronchopleural fistula

Healed Tuberculosis

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.

A Ghon lesion is a calcified granuloma
A calcified granuloma + hilar node calcification is a Ranke complex

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.

Adenitis

Above pictures: “Chest Radiography Interpretation: Pulmonary TB” by Lisa Chen, MD. Department of Medicine, San Francisco General Hospital. Michael Gotway, MD, UCSF

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

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.

Lympahtic Tuberculosis
Lymhatic Tuberculosis

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.

Lymphatic Tuberculosis: Axilla lymph node
In this patient, the affected subclavicular lymph node had undergone complete caseation causing discoloration of the skin.
This patient has chronic peripheral lymphatic tuberculosis. Some lesions healed with scarring (posterior), while others still show activity (anterior).
This patient was referred to the tuberculosis clinic with the question of otitis media. On physical exam, there was no otitis visible on otoscopic exam. And the patients’ endorsement of systemic illness (ie weight loss, night sweats, etc) indicated something more severe was likely going on. The pre-auricular lesion was cold to the touch and fluctuant. The mass was aspirated and a gram stain showed no organisms. After careful examination of a Ziehl-Neelsen stain smear, acid- fast bacilli were found indicating tuberculosis infection.
This abscess was close to breaking through the skin, yet it felt cold to the touch and the child felt remarkably little pain on palpation of the lesion. Such a finding should raise a high index of suspicion for tuberculosis.
This patient had a seven-year history of lymphatic tuberculosis. Many lesions have apparently healed, but some are still active (note inflammation surrounding the most caudal axillary lesion).
At first sight, all of the lesions resulting from peripheral lymphatic tuberculosis in this patient have healed. However, as the example of the previous patient demonstrates, one can never be certain. Curative chemotherapy should be offered to any patient with signs of tuberculosis of peripheral lymph nodes.

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.

Skin

This patient has celluitic infection with a sinus draining from both the dorsal and volar aspects of the thumb. Pus was evaluated on a Lowenstein-Jensen medium, which enabled Mycobacterium tuberculosis to be isolated.
In this patient, diagnosis of tuberculosis of the ankle was possible by testing for acid-fast bacilli from the visible secretions draining from this cutaneous sinus.

Bone

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.

This patient presented with several skin lesions (neck, axilla, arm and hand). On CXR he had a segmental lesion of the spine.
The hump on the arm is the clearly positive tuberculin skin test reaction shown outlined in black.
The radiograph shows the complete destruction of a distal phalanx due to TB infection.
This patient with tuberculosis of the spine also has a visible abscess of the lower left back. While abscesses such as these can confuse diagnosis, TB should always be on the differential in areas or populations where it is very prevalent. The abscess was warm to the touch and an initial Gram stain showed Gram-positive cocci, which would not be indicative of TB, but Acid-fast bacilli were also found, confirming tuberculosis of the spine with a super-infected abscess.

Tuberculosis Spondylitis

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

Lesions of the spine are usually anterior in location. The bony structure adjacent to both sides of the disk becomes eroded, leading to narrowing of inter-vertebral disk space (Left side normal)
As a result of the anterior lesion, the disk or disks collapse in the weakened area, causing a triangular shape
In chronic cases, there might be attempts to repair via normal bone remodeling. Shown here is ossification surrounding the vertebral body. This would solidify the kyphosis of a potential gibbus
Kastert J, Uehlinger E. Handbuch der Tuberkulose. Vol 4, p. 455-461. Hein J, Kleinschmidt H, Uehlinger E (eds). Thieme, Stuttgart, 1964. Reproduced with permission.

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.

On CXR, spinal TB is often obscured in an AP view. On this lateral image, a gibbus formed after anterior collapse of the vertebrae. The patient will likely have kyphosis due to the newly bent structures
Extensive destruction in two adjacent vertebrae
Two vertebrae collapsed to the height of one
In addition to the paralysis caused by the visible lower lumbar lesion, this child also had a pyopneumothorax (and an accelerated response to a BCG vaccination)
A severe gibbus in the lower thoracic region
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.

Tuberculosis of the Joint

This girl had an almost completely destroyed hip joint, as seen in the SI joints and right femur
The diagnosis of tuberculosis in the left hip in this boy was made after the development of a sinus draining through the skin. Sampling of the fluid led to the discover of acid-fast bacilli
Tuberculosis of the wrist