A Case Report of a Tongue Ulcer Presented as the First Sign of Occult Tuberculosis

Seo-Yeong Kim; Jin-Seok Byun; Jae-Kap Choi; Jae-Kwang Jung

Disclosures

BMC Oral Health. 2019;19(67) 

In This Article

Discussion

TB is the ninth leading cause of death worldwide and leading cause from a single infectious agent, ranking above HIV/AIDS. The World Health Organization estimated that about 10.4 million people were infected with TB in 2016: 90% were adults, 65% were male, 10% were people living with HIV (74% in Africa), and 56% were living in five countries, namely India, Indonesia, China, the Philippines, and Pakistan.[9] While the global incidence of TB is slowly falling by about 2% per year, it was reported that 39,000 people were still infected with TB and 2600 people died from it in 2016 in South Korea.[9,10]

The most vulnerable region to TB is pulmonary system, and infection does not usually spread to other parts of the body in most patients. However, in rare instances, progressive pulmonary TB spreads by self-inoculation via infected sputum, blood, or lymphatic system to cause secondary lesions of TB at organs other than the lung.[11] Extrapulmonary TB of pleura, lymphatics, bone, genitourinary system, meninges, peritoneum, or skin occurs in approximately 15% of TB patients.[12] TB can affect the head and neck region, including the oral cavity. Oral TB lesions may either be primary or secondary to pulmonary TB, with secondary lesions being more common. The oral lesions usually present with a stellate ulcer, most commonly on dorsum of the tongue.[4]

Lingual TB may appear as ulcers, nodules, fissures, tuberculomas, or granulomas. The most frequent lesion is a superficial ulcer, characterized by undermined edges, a granulating floor, and occasional small tuberculous nodules around the periphery.[13] The ulcer may be ragged and indurated and is often painful.[14] The histological criteria for a diagnosis of oral TB include presence of granulomatous inflammation with epithelioid cells and Langhans giant cells or AFB seen on Ziehl-Neelsen staining of biopsy specimens.[6]

Once in the lung, bacilli are subjected to phagocytosis and degradation by resident macrophages. However, some bacilli can escape lysosomal delivery and survive within the macrophage. M. tuberculosis remaining in macrophages is kept in check within the granulomas, which are clusters containing mycobacteria-infected macrophages in the center, surrounded by different types of immune cells such as macrophages, T and B lymphocytes, dendritic cells, endothelial cells, fibroblasts, and granulocytes. Mycobacteria might exist in a so-called 'dormant' state as long as host immunity is effective.[12] Therefore, presence of granuloma indicates the balance between host resistance and M. tuberculosis virulence as distinct feature of latent pulmonary TB. Many asymptomatic humans hold virulent bacteria in granulomas. While controlling the infection of bacteria, granulomas also serve as a hideout for long-term survival of bacteria.[15]

Once patients are diagnosed with TB, personalized treatments should be performed with anti-TB drugs on the basis of clinical examination. Treatment of latent TB infection is also required to inhibit the development of active TB disease in those already infected with M. tuberculosis.[9] The oral lesions can be relieved after pharmaceutical management of systemic TB.

Oral lesions of TB exhibit a nonspecific clinical presentation and are often overlooked in differential diagnosis, even by dentists. However, when oral lesions do not adequately respond to local treatments, dentists should include TB in differential diagnosis. Careful anamnesis and clinical and radiological examination could play a leading role in clinical diagnosis of TB. In the present case, aphthous ulcer and traumatic ulcer could be ruled based on the prolonged course of the ulcer and the absence of trauma in the history. As various types of oral ulcers might also be caused by other systemic diseases—including Crohn's disease, syphilis, blastomycosis infection, and even Langerhans cell histiocytosis, histopathological examination and culture of microorganisms should be considered for definite diagnosis.[16,17]

In our case, it was initially difficult to differentiate TB from other focal lesions because patient did not present any other systemic symptoms except for persistent oral ulcer. Considering his medical history of TB over 40 years ago, it was possible that M. tuberculosis TB incubated in his lung reactivated into an active and virulent state.

Recently, despite the decreasing tendency of developing new cases of TB in Korea, TB incidence and mortality rate in Korea are still the highest among Organization for Economic Co-operation and Development (OECD) countries. As dentists are the first health care professionals that frequently encounter various oral lesions, it is important to understand the various oral manifestations of TB for avoiding a delayed diagnosis and poor prognosis. In summary, oral TB should be included in differential diagnosis of persistent oral lesions when diagnosing patients with a history of TB, even though evidence of TB is rare in oral cavity. Accurate diagnosis is critical for optimal treatment by focusing on the pathological source, to avoid inappropriate oral therapy.

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