In 15–20% of active cases, the infection spreads outside the lungs, causing other kinds of TB.[19] These are collectively denoted as "extrapulmonary tuberculosis".[20] Extrapulmonary TB occurs more commonly in people with a weakened immune system and young children. In those with HIV, this occurs in more than 50% of cases.[20] Notable extrapulmonary infection sites include the pleura (in tuberculous pleurisy), the central nervous system (in tuberculous meningitis), the lymphatic system (in scrofula of the neck), the genitourinary system (in urogenital tuberculosis), and the bones and joints (in Pott disease of the spine), among others. A potentially more serious, widespread form of TB is called "disseminated tuberculosis", it is also known as miliary tuberculosis.[9] Miliary TB currently makes up about 10% of extrapulmonary cases.[21]