Tuberculosis (TB) is an infectious disease caused by the bacterium Mycobacterium tuberculosis, which typically infects the lungs. The infection can spread beyond the respiratory system, leading to Extrapulmonary TB (EPTB). The most common form of EPTB is Tuberculous Lymphadenitis (TL), which specifically targets the lymph nodes. This infection causes the lymph nodes to become inflamed and enlarged, most often those located in the neck, a condition historically called “scrofula.” TL is a localized manifestation of a systemic disease, and understanding how the bacteria affects the lymphatic system is important.
How Tuberculosis Affects the Lymphatic System
The process begins when Mycobacterium tuberculosis bacilli are engulfed by immune cells, such as macrophages, often after being inhaled into the lungs. These infected macrophages travel through the lymphatic system, draining from the primary site of infection to the regional lymph nodes. The lymph nodes then become the new focus of infection, which can occur during the initial infection or through the reactivation of a dormant infection.
Once inside the lymph node, the immune response attempts to contain the bacteria, resulting in the formation of structures called granulomas. A granuloma is characterized by a central area of dead tissue, known as caseous necrosis, surrounded by specialized immune cells. Caseous necrosis often has a distinct, cheese-like appearance and is a hallmark of this infection.
The cervical lymph nodes in the neck are the most frequently involved sites, accounting for the majority of TL cases, though nodes in the axillary or inguinal regions can also be affected. As the infection progresses, inflammation can spread beyond the node, causing surrounding tissues to become inflamed (periadenitis). This chronic inflammation causes the nodes to swell and change in texture, producing the visible signs of the disease.
Recognizing the Signs of Tuberculous Lymphadenitis
The primary sign of Tuberculous Lymphadenitis is the gradual, usually painless swelling of the affected lymph nodes (lymphadenopathy). This swelling typically develops over several weeks to months and often affects only a single group of nodes, most commonly in the neck. The enlarged nodes are often described as firm and rubbery to the touch.
As the disease advances, the inflamed nodes may adhere to one another due to periadenitis, forming a fixed mass known as “matting.” The central caseous material can break down in later stages, leading to a “cold abscess.” This is a collection of pus without the typical signs of heat and redness seen in other infections. This abscess may eventually rupture through the skin, creating a draining sinus tract or fistula that discharges pus.
While localized swelling is the most common presentation, some patients experience systemic symptoms, though these are often milder than those seen in active pulmonary TB. General signs can include a low-grade fever, night sweats, and unexplained weight loss. However, many patients only present with painless lymph node enlargement, which can make diagnosis challenging without further testing.
Diagnosis and Confirmation Procedures
Confirming a diagnosis of Tuberculous Lymphadenitis requires more than just a physical examination due to the nonspecific nature of the swelling. Medical professionals rely on specific diagnostic tests to identify the bacteria and characterize tissue changes. The initial and least invasive procedure used is Fine Needle Aspiration (FNA) cytology, which involves using a thin needle to extract cells and fluid from the enlarged node for examination.
The aspirate obtained via FNA is analyzed for characteristic cellular patterns, such as epithelioid granulomas and caseous necrosis, which strongly suggest tuberculosis. The material can also be subjected to specific staining techniques, like the Ziehl-Neelsen stain, to look for acid-fast bacilli (Mycobacterium tuberculosis bacteria).
Culture remains the gold standard for definitive diagnosis, as it confirms the presence of the organism, although this process can take several weeks. To overcome the slow nature of culture, molecular tests such as Nucleic Acid Amplification Tests (NAATs), including PCR, are frequently used. These tests rapidly detect the genetic material of M. tuberculosis and can provide an early indication of drug resistance, which guides treatment. If FNA and molecular testing are inconclusive, an excisional biopsy (surgically removing the entire lymph node) may be performed for detailed histopathological examination.
Standard Treatment Protocols
The management of Tuberculous Lymphadenitis relies on a prolonged course of anti-tuberculosis medication, similar to that used for pulmonary disease. The standard pharmacological approach involves a combination of four drugs during the intensive phase, commonly referred to as RIPE therapy. This regimen typically includes Rifampicin, Isoniazid, Pyrazinamide, and Ethambutol.
The intensive phase usually lasts for two months, followed by a continuation phase consisting of Rifampicin and Isoniazid. The total duration of multi-drug therapy for drug-susceptible TL is typically six to nine months, with a six-month course being the most common. Full adherence to the prescribed drug regimen is important to ensure the infection is eradicated and to prevent the development of drug-resistant tuberculosis.
Surgical intervention is generally reserved for complications such as large, painful abscesses or for diagnostic purposes when other methods have failed. Patients should be aware that lymph node swelling may not resolve immediately and can sometimes enlarge or persist during effective treatment, known as a paradoxical reaction. This slow response requires continued close monitoring by a healthcare provider.