Extrapulmonary TB is active TB in organs other than the lungs. About 15% of the 7 million incident TB cases globally notified in 2018 were extrapulmonary TB; among WHO regions, prevalence ranged from 8% in the Western Pacific; to 15–17% in Africa, the Americas, Europe and South-East Asia; and to 24% in the Eastern Mediterranean (5). The WHO European Region is facing an increasing notification rate of extrapulmonary TB: in this region seven countries (Finland, the Netherlands, Norway, Sweden, Turkey, the United Kingdom and Uzbekistan) reported more than 30% of cases (39).
Overall, among both adults and children, about two of every three extrapulmonary TB cases are represented by pleural and lymph node TB (40). In settings with a high prevalence of HIV infection, lymph node TB represents about 10% of all TB cases (41). Osteoarticular, urogenital, intra-abdominal, pericardial and meningeal TB are less frequent (40). Tuberculous meningitis is important both for being clinically severe and for being largely preventable in children by vaccinating with bacille CalmetteGuérin (BCG), ideally at birth (42).
Compared with pulmonary TB, extrapulmonary TB is more difficult to diagnose because it can mimic other organ-specific diseases, clinical samples for bacteriological situations are difficult to obtain for culture, and digital imaging is not always available. In addition, extrapulmonary TB is often paucibacillary (40). Pericardial, meningeal and disseminated (miliary) TB forms are more likely to result in a fatal outcome.