Tuberculosis of the tongue is a rare manifestation of tuberculosis, a disease primarily associated with the lungs. While the oral cavity can be affected, the tongue is an unusual location for this infection. Lingual tuberculosis cases have been documented since 1888, often as isolated reports. Its infrequency makes diagnosis challenging, as it can mimic other common oral lesions.
Understanding Tuberculosis Tongue
Tuberculosis of the tongue is an extrapulmonary form of tuberculosis, meaning it occurs outside the lungs. The infection is caused by the bacterium Mycobacterium tuberculosis. Oral tuberculosis can present in both primary and secondary forms.
Primary infection is uncommon, occurring when Mycobacterium tuberculosis bacteria are directly inoculated onto the oral mucous membrane, often in younger patients. Secondary infection, more frequently observed, arises from the spread of active tuberculosis from the lungs or other organs. This can happen through self-inoculation with infected sputum, or through hematogenous spread via the bloodstream. The intact oral mucosa, continuous cleansing action of saliva, and antibodies in saliva provide a protective barrier against tubercle bacilli. However, local trauma or chronic irritation, such as from rough teeth or poor oral hygiene, can create an entry point for the bacteria, facilitating lesion development.
Recognizing the Signs
The clinical presentation of tuberculosis of the tongue varies, but often involves lesions. These commonly appear as ulcers, which can be irregular, pale, and indolent with undermined margins and granulations. Other forms include nodules, fissures, papules, or a cold abscess.
Affected areas include the tip, lateral borders, dorsum (top surface), midline, and base of the tongue. Patients often experience severe pain, interfering with eating and speaking, along with difficulty swallowing (dysphagia) and sometimes impaired speech (dysarthria). Swelling of the tongue may also be present. Regional lymphadenopathy, or enlarged lymph nodes in the neck and under the jaw, can occur. These non-specific symptoms can resemble other oral conditions like traumatic ulcers, aphthous ulcers, or oral cancers, making definitive diagnosis challenging without further investigation.
Diagnosing Tuberculosis Tongue
Diagnosing tuberculosis of the tongue involves a thorough clinical evaluation and specific laboratory tests. A detailed patient history is obtained, including any potential tuberculosis exposure or history of the disease elsewhere in the body. However, clinical signs alone are often insufficient for a definitive diagnosis due to their non-specific nature.
The primary diagnostic method is a biopsy of the tongue lesion for histopathological examination. This involves taking a tissue sample from the affected area to be examined under a microscope, identifying characteristic granulomas with caseous necrosis (a type of tissue death). Microbiological culture of the biopsy specimen is also performed to isolate and identify Mycobacterium tuberculosis, though results may take several weeks due to the slow growth of the bacteria. Supportive diagnostic tests include Polymerase Chain Reaction (PCR) for rapid detection of mycobacterial DNA, a chest X-ray to check for co-existing pulmonary tuberculosis, and a tuberculin skin test (TST) or interferon-gamma release assay (IGRA) to assess for tuberculosis infection.
Treatment and Recovery
Treatment for tuberculosis of the tongue mirrors the standard multi-drug antitubercular therapy used for other active forms of tuberculosis. This regimen involves a combination of four drugs during an initial phase: isoniazid, rifampicin, pyrazinamide, and ethambutol, administered daily for approximately two months. Following this intensive phase, a continuation phase involves two drugs, such as isoniazid and rifampicin, for an additional four to seven months, bringing the total treatment duration to about six to nine months.
Adherence to the full course of treatment is important to ensure complete eradication of the bacteria, prevent the development of drug resistance, and facilitate full recovery. Most patients with tongue tuberculosis respond well to antitubercular therapy, with lesions often healing completely within two months of starting treatment. Regular follow-up appointments are necessary to monitor the patient’s response, manage any side effects, and confirm the cure.
Risk Factors and Prevention
Several factors can increase an individual’s susceptibility to developing tuberculosis of the tongue. A compromised immune system is a significant risk factor, as seen in individuals with HIV/AIDS, those undergoing immunosuppressive therapy for conditions like rheumatoid arthritis or Crohn’s disease, or organ transplant recipients. Pre-existing active pulmonary tuberculosis is a common precursor, as the bacteria can spread from the lungs to the oral cavity. Close contact with individuals who have active tuberculosis, living in overcrowded conditions, and poor nutritional status also elevate the risk.
Preventive measures for tuberculosis generally include vaccination with Bacille Calmette-Guérin (BCG) in regions where tuberculosis is prevalent, although it primarily offers partial protection against severe forms of the disease in infants and young children. Early diagnosis and prompt treatment of active tuberculosis cases are important to prevent the spread of the infection to others, including to extrapulmonary sites like the tongue. Public health efforts, such as contact tracing and screening programs, also contribute to controlling the spread of the disease.