Tuberculosis (TB) killed 1.25 million people in 2023 alone, as per data from the World Health Organisation (WHO). With rising cases, it has probably returned to being the world’s leading cause of death from a single infectious agent, following three years in which it was replaced by coronavirus disease (COVID-19). While it is known to be a condition impacting the lungs, there are rare cases where it spreads outside the lungs (extrapulmonary TB). One of them is breast Tuberculosis (TB).What Is Breast TB An How Does It Spread?The first case of breast TB was recorded by Sir Astley Cooper who described it as "scrofulous swelling of the bosom”. Tuberculosis is caused by Mycobacterium tuberculosis and affects primarily the lungs. Breast Parenchyma (the glandular and ductal tissue within the breast, which is responsible for milk production and storage) is resistant to this TB-causing bacteria. However, in several cases, it is spread to the breast tissue. In primary form, it is spread of infection through abrasions in the skin of the breast or through cracks in the nipple. The secondary form of this disease can be caused by the retrograde spread from infected axillary lymph nodes, or by direct spread from tissue in the ribs, sternum, shoulder joint, costochondral cartilage, or pleura adjacent to the mammary gland tissue.According to a 2012 study, Breast TB is an uncommon form of the disease occurring outside the lungs, comprising less than 0.1% of breast conditions in developed nations but rising to 3-4% in regions with high tuberculosis prevalence like India and Africa. It primarily affects women of reproductive age who have given birth and are lactating.Causes Of Breast TBThere are several ways in which you can contract breast TB. The top three of them are: Hematogenous spread which is the most common and results in lung infectionLymphatic spread via dissemination to more specifically axillary lymph nodesDirect spread from the chest wall or pleuraIt is pertinent to note that this condition is common among people with compromised immunity levels. The list includes HIV positives and those taking immunosuppressive medications. How To Identify Breast TB? A painless, firm lump is the most common presentationSome people may feel pain or even tenderness at some pointNipple discharge which may be bloody or purulentThe overlying skin may show ulceration, dimpling, or sinus tract formationSwelling of the axillary lymph nodes.