Tuberculosis (TB) remains a global health concern, affecting millions worldwide. While most people associate TB with the lungs, extra pulmonary tuberculosis (EPTB) impacts areas outside the respiratory system. EPTB can manifest in diverse ways, affecting almost any part of the body, and presents unique challenges for diagnosis and treatment. This form of TB often requires specialized approaches for effective management and better patient outcomes.
Defining Extra Pulmonary Tuberculosis
Extra pulmonary tuberculosis (EPTB) is an infection caused by the bacterium Mycobacterium tuberculosis, targeting organs and tissues beyond the lungs. While pulmonary TB primarily affects the lungs, EPTB represents a significant proportion of active TB cases, ranging from 20% to 40%. EPTB often presents with symptoms less obvious than the persistent cough associated with lung TB.
The bacteria can spread from a primary infection site, often the lungs, through the bloodstream or lymphatic system to almost any other organ system. This allows Mycobacterium tuberculosis to establish new infection sites, leading to a wide array of clinical presentations. EPTB is more frequently observed in individuals with weakened immune systems, such as those with HIV, where it can occur in over 50% of cases, and in young children.
Diverse Manifestations of Extra Pulmonary Tuberculosis
Extra pulmonary tuberculosis can affect various parts of the body, leading to a wide range of symptoms depending on the specific site of infection. Its diverse manifestations often mimic other conditions, which can delay diagnosis. Each location presents distinct clinical signs reflecting the affected organ’s function.
Lymph node TB, also known as tuberculous lymphadenitis, is the most common form of EPTB. It presents as a gradual, usually painless swelling of one or more lymph nodes, most often in the neck. Patients may also experience general symptoms like mild fever, decreased appetite, and weight loss. In some cases, pus formation can occur within the lymph nodes, potentially leading to rupture and pus release.
Skeletal TB, or bone and joint TB, occurs when Mycobacterium tuberculosis infects the skeletal system, frequently impacting the spine (Pott’s disease) or major weight-bearing joints like the hips and knees. Symptoms include progressive or constant pain in the affected bones, swelling, stiffness, and potential deformities. Spinal involvement can lead to severe back pain and, if untreated, may result in vertebral collapse, causing neurological complications or paralysis.
Genitourinary TB affects the kidneys, bladder, and reproductive organs. Symptoms can be nonspecific, including increased frequency of urination, painful urination (dysuria), blood in the urine (hematuria), and lower abdominal discomfort. In men, it might lead to testicular swelling or perineal pain, while in women, it can cause pelvic pain or menstrual irregularities. Unexplained infertility in both men and women is sometimes a symptom.
Central Nervous System (CNS) TB, particularly tuberculous meningitis, is a severe form affecting the brain and spinal cord. Symptoms often develop gradually over weeks, including persistent headache, fever, nausea, vomiting, and altered mental status, potentially progressing to drowsiness or coma. Tuberculomas, masses of TB infection in the brain or spinal cord, can also form and cause neurological deficits.
Gastrointestinal TB can involve any part of the digestive tract, including the intestines, peritoneum, stomach, liver, and spleen. Common symptoms include abdominal pain, weight loss, fever, and changes in bowel habits, with diarrhea more common than constipation. Patients may also experience abdominal distension due to fluid accumulation, an enlarged liver, or swollen abdominal lymph nodes.
Other less common manifestations include pericardial TB, involving the sac surrounding the heart and causing chest pain or fluid buildup, and pleural TB, affecting the lining of the lungs, leading to fever and pain with breathing. Cutaneous TB presents as skin lesions, and ocular TB can affect various parts of the eye, sometimes mimicking other eye conditions.
Identifying Extra Pulmonary Tuberculosis
Diagnosing EPTB often requires a combination of clinical assessment and specialized tests, as its symptoms can be non-specific and bacteria are typically less abundant in extrapulmonary sites. The diagnostic process begins with thorough clinical suspicion based on the patient’s medical history and presenting symptoms. Healthcare providers look for systemic indicators such as persistent swelling, pain, fever, or unexplained weight loss, tailored to the suspected site of infection.
Imaging techniques play a significant role in pinpointing the affected area and assessing disease extent. X-rays, CT scans, and MRI scans are commonly employed, with the specific modality chosen based on the suspected infection location. For example, an MRI is useful for detecting TB in the central nervous system, while CT scans can reveal abnormalities in abdominal organs.
Definitive diagnosis frequently relies on obtaining tissue samples from the affected area through a biopsy. Pathologists examine these specimens microscopically for characteristic TB features, such as granulomas with caseous necrosis. Microbiological tests are then performed on these samples, including microscopic examination for acid-fast bacilli (AFB) and culture methods to grow Mycobacterium tuberculosis. Molecular tests, like PCR, rapidly detect Mycobacterium tuberculosis DNA and can also identify drug resistance, offering quicker results than traditional cultures.
Immunological tests, such as the tuberculin skin test (TST) or interferon-gamma release assays (IGRAs), can indicate exposure to TB bacteria. However, these tests cannot distinguish between latent infection and active EPTB, nor pinpoint the exact location of the disease. While a positive result suggests the body has been sensitized to TB, a negative result does not completely rule out EPTB, especially in individuals with weakened immune systems.
Management and Treatment
The management of extra pulmonary tuberculosis involves a comprehensive approach, primarily centered on multi-drug antituberculosis therapy. Treatment typically consists of a combination of several antibiotics to effectively eliminate Mycobacterium tuberculosis bacteria. This combination therapy is important for preventing the development of drug-resistant strains.
The duration of treatment for EPTB is prolonged, often lasting from 6 to 12 months or even longer, depending on the specific site of infection, disease severity, and patient response. For instance, tuberculous meningitis may require treatment for 9 to 12 months due to the serious risk of disability and mortality. Completing the full course of prescribed medications is essential to ensure bacterial eradication and minimize the risk of relapse or drug resistance.
Directly Observed Treatment, Short-course (DOTS) is a strategy sometimes employed to ensure patient adherence to the treatment regimen. Under DOTS, a healthcare worker observes the patient taking their medication, helping ensure consistency and completion of the full course. In certain EPTB cases, particularly those with complications or significant tissue damage, additional interventions may be necessary. These can include surgical procedures for drainage of abscesses, removal of damaged tissue, or addressing obstructions. Corticosteroids may also be administered in specific situations, such as tuberculous meningitis or pericarditis, to reduce inflammation and mitigate severe complications.
Transmission and Protective Measures
Extra pulmonary tuberculosis is generally not contagious in the same manner as pulmonary TB. Unlike lung TB, where bacteria are expelled into the air through coughing, sneezing, or speaking, EPTB typically involves bacteria contained within specific organs or tissues. This means individuals with EPTB, without co-existing pulmonary involvement, do not usually transmit the infection through airborne droplets.
Prevention strategies for TB aim to control bacterial spread and protect individuals at risk. Treating latent TB infection (LTBI) in individuals exposed to the bacteria but without active disease is a significant preventive measure. This can involve a course of medication to prevent the latent infection from progressing to active TB disease.
The Bacille Calmette-Guérin (BCG) vaccine is another protective measure used in many parts of the world, particularly in countries with a high incidence of TB. While its effectiveness against pulmonary TB in adults can vary, the BCG vaccine has shown significant protection against severe forms of TB in young children, including tuberculous meningitis and disseminated disease. However, it does not always prevent primary infection or latent TB reactivation.