Tuberculous mastitis is often considered a form of granulomatous mastitis secondary to Mycobacterium tuberculous infection of the breast. Some authors however reserve the term granulomatous mastitis to idiopathic granulomatous mastitis.
Tuberculous mastitis can mimic many other pathologies in both clinical presentation and on imaging.
Isolated primary involvement of the breast is extremely rare. It estimated incidence is less than 0.1% of all breast lesions in Western countries and 3-4% of all breast lesions in endemic countries . It typically affects young lactating multiparous women.
It can present either as an abscess or as a unilateral, painless breast hard mass (~60% of cases ). Approximately half of cases may present with mastalgia while ~10% may complain of a skin sinus .
Tuberculous involvement of the breast can occur in two forms. The primary form is an infection of the breast through abrasions or through the openings of ducts in the nipple. The secondary form is the result of reverse lymph flow in the axillary lymph nodes or it may be due to direct spread of the infection from intra-thoracic foci.
According to clinical, radiological and pathological appearance of the disease there can be three types of breast tuberculosis :
- nodular tuberculosis:
- characterized by a well-circumscribed, slowly growing, painless mass
- often an enlarging mass infiltrates the skin which then becomes painful, causing ulceration, and discharge from one or more sinus tracts
- this course makes differentiation from carcinoma very difficult
- diffuse type or disseminated tuberculous mastitis:
- characterized by multiple foci, which may lead to sinus formation
- overlying skin is thickened and painful ulcers may develop
- axillary lymph nodes are frequently infiltrated
- sclerosing type:
- excessive fibrosis is the dominant feature
- slow-growing, and suppuration is rare
- clinically there is a hard, painless lump with nipple retraction
Imaging features are often non-specific with significant overlap with various other pathological entities.
Specific mammographic features can vary depending on the whether it is nodular diffuse or sclerosing type.
Often there is an ill-defined breast mass, skin thickening, and a reduction in size of the affected breast. Nipple retraction and coarse stromal texture may be a frequent features . In the context of tuberculous breast abscess, mammographic demonstration of a dense tract connecting an ill-defined breast mass to a localized skin thickening and bulge (skin bulge and sinus tract sign) is considered a strongly suggestive feature . Approximately 40% may have axillary or intra-mammary adenopathy visible on mammography while ~20% may have macro-calcification and ~10% may have skin sinus. Large, dense, calcified axillary nodes may be demonstrated with appropriate auxiliary views and are also considered to be suggestive of the disease .
Approximately 60% may have a hypoechoic masses while ~40% may have focal or sectorial duct ectasia. Half of cases may have axillary adenopathy detectable on ultrasound .
Sir Astley Cooper was the first to describe a case of breast tuberculosis in 1829 and called it “scrofulous swelling of the bosom”. Later, in 1952, McKeown and Wilkinson described two forms of breast tuberculosis, the primary in which breast infection is the only manifestation of the disease and the secondary one in which the patient had already tuberculosis diagnosed elsewhere .