Imaging diagnosis of sternal tuberculosis- A report of two cases of the ancient disease with a new demeanour.

Tuberculosis is an ancient disease known to have existed even in the Egyptian civilization. It is estimated that a quarter of the world's population is already infected and 1 million will die of the disease, in the current year. Although tuberculosis may occur in any organ, extra- pulmonary tuberculosis accounts for 10%-14% of all cases of tuberculosis. Skeletal involvement comprises only 1 to 5 % of all types of tuberculosis and the most frequently involved site in the skeleton is the vertebral column, amongst the skeletal structures, the sternum is involved very rarely, accounting for just 1-2% of all bone and joint tuberculosis. We report two cases of sternal tuberculosis,and enumerate the imaging appearances seen at ultrasound, CT and MRI and also highlight a relatively underemphasised complication of mediastinal involvement due to a retrosternal abscess. Rapid diagnosis by imaging studies led to early treatment and prevented catastrophic consequences of diffuse mediastinitis. Awareness of tuberculosis and its atypical skeletal manifestations is important not only in developing countries with endemic disease, but also in developed countries, due to its resurgence by the HIV epidemic and also because extensive international travel and transcontinental migration continues to facilitate greater disease transmission.