Breast tuberculosis (BTB) is a rare type of extrapulmonary tuberculosis (TB). A BTB case was first described by Sir Astley Cooper in 1829 as a scrofulous swelling of the breast. Mammary gland tissues, skeletal muscles and the spleen are resistant to the multiplication and survival of the tubercle bacillus. It has been reported that the uncommon occurrence of BTB may be due to this feature (1). BTB commonly affects females of a reproductive age (range, 20–40 years), whereas it is rare in prepubescent females, elderly women and males. BTB lesions can mimic carcinoma in elderly patients, while it may be misdiagnosed as a pyogenic breast abscess in young patients. Thus, establishing an accurate diagnosis of BTB is often challenging. Breast tuberculosis has no specific clinical features and has been termed as a ‘great masquerader’ as a result of its different presentation. The history of the presenting symptoms in BTB is typically less than a year; however, it varies from a few months to several years (2). A lump in the central or upper outer quadrant of the breast is the most common form of presentation. Upon physical examination, common symptoms include a mass, tenderness, pain, swelling or fluctuation in abscess formation in the breast, presenting with or without discharging sinuses (2,3).

Radiological imaging is not diagnostic. Diagnosis is based on the identification of typical histological features or the tubercle bacilli under microscopy or culture (2–4). However, smear positivity for acid-fast bacilli by Ziehl-Neelsen staining is low, and in the majority of cases, the diagnosis can only be accurately diagnosed by histological identification of the typical necrotizing granulomatous lesion (5). It has been reported that, in endemic countries, the incidence is 3.0–4.5% of all breast lesions (6). BTB constitutes <1% of all diseases of the breast in developed countries. However, the incidence of the disease is higher in countries endemic for TB, such as the Indian subcontinent, where BTB may comprise up to 4.0% of breast diseases (4,7). In addition, tuberculosis constitutes 0.025–0.1% of all surgically treated diseases of the breast (8). The treatment of breast tuberculosis consists of anti-tubercular chemotherapy and surgery with specific indications (2).

In the present study, a retrospective analysis of 7 BTB cases was conducted, with the aim to evaluate the characteristics of this disease. The aims of the present study was to evaluate the clinical features, demographic data, diagnostic methods, therapeutic regimens and duration of therapy in BTB cases.

BTB is a rare form of extrapulmonary TB that is associated with risk factors including past history of suppurative mastitis, trauma, lactation, multiparity and acquired immune deficiency syndrome. Lactation has been demonstrated to increase the susceptibility of the breast to TB. During lactation, the increased vascularity of the breast may facilitate infection and dissemination of the bacilli. However, there were no pregnant or lactating women in the patient cohort of the present study. The majority of cases had an age between 20 and 40 years. It has been previously shown that unilateral involvement is common in BTB. In the current study, unilateral involvement was observed in 6/7 cases, which is consistent with previous reports.

BTB commonly presents with the following clinical characteristics: Ill-defined, solitary, unilateral solid lump located in central or upper outer quadrant of the breast. The mass may be solid, irregular and occasionally fixed to the muscle, skin or chest wall. Bilateral involvement and presence of multiple lumps are rarely reported (in <3% of cases) (9). In the cases reported in the current study, the symptoms included presence of a mass, tenderness, pain, swelling and fluctuation in abscess formation in the breast, with or without discharging sinuses, while the lesions were generally located in the upper outer quadrant of the breast.

The main routes through which TB lesions spread and the breast may become infected with TB bacilli includes by haeamatogenous routes, lymphatic extension from primary foci of disease in the lymph nodes of the mediastinum, axilla and parasternal and cervical regions, direct inoculation and by ductal infection (10) The disease presents in two forms, primary and secondary BTB. Primary BTB is rarely reported, and the breast is the only affected area in this form of the disease. By contrast, secondary BTB is more frequently reported, and a prior history of TB is common in these cases (4,7,9). In the present study, the only organ involved was the breast, and thus all cases presented primary BTB.

No specific features of BTB are observed in mammography and ultrasonography examinations. Mammography can be used to identify the three different patterns of TB, which include the nodular, disseminated and sclerosing lesions. The nodular pattern is indicated by the presence of slow-growing, painless and well-circumscribed lesions. At an advanced stage, retraction and sinus formation may be observed through involvement of the skin. In addition, the disseminated pattern presents as interconnected focal lesions, sinus formation and skin thickening. Finally, the sclerosing pattern commonly occurs in older females and presents as slow-growing, dense fibrous tissue. Generally, no microcalcification or nipple retraction are observed. According to radiological findings, the nodular pattern may be misdiagnosed as fibroadenoma. Thorax computed tomography is important for evaluating chest wall, musculoskeletal and other involvement, and can also be used as a guide for obtaining tissue samples for diagnosis (4).

A suspicion of BTB is essential for diagnosis. The gold standard for diagnosis of BTB is the detection of the etiologic agent using Ziehl-Neelsen staining or culturing; however, AFB test is rarely positive. Histopathological examination, FNAC, true-cut biopsy or open biopsy are also important for diagnosis, with FNAC being the most widely used initial invasive diagnostic method. In order to establish a diagnosis, the present study, FNAC was used in 2 cases, excisional biopsy in a another 2 case, incisional biopsy in 1 case and total excision in 2 cases. Granulomas may be detected anywhere in breast tissue and granuloma is often composed of histiocytes, Langhans giant cells, lymphocytes, rare plasma cell and eosinophilic caseous necrosis. In the case with mastitis and fat necrosis inflammation presented in the current study, no improvement was observed following nonspecific antibiotherapy and the patient was then successfully treated with anti-TB drugs. In past years, mastectomy was the common treatment of BTB; however, in recent years, the success of antituberculous drug therapy is high and surgical intervention is rare (10–12).

Tanrikulu et al (13) reported 27 BTB cases between 2004 and 2008, with all cases being newly-diagnosed patients with a mean age of 31.5±8.4 years. The study reported that cases presented with breast swelling (48.1%), mass and fluctuation in abscess formation (40.7% each) and painful breasts (18.5%) (13). Of the included patients, 1 case had previous TB lymphadenitis in the cervical region, while the remaining cases had no history of TB; thus, 26/27 cases were diagnosed with primary BTB, and ~73.0% of cases were diagnosed using FNAC (13). In addition, Kalaç et al (8) presented 5 BTB cases with a mean age between 20 and 63 years. All the reported cases had children and were breast-feeding, while all lesions were found to be unilateral and AFB testing revealed negative results. One of the cases had received anti-TB treatment for pulmonary TB 10 years earlier (8). Diagnosis was established histopathologically from the excisional biopsy material. Caseating granulomatosis was also identified in the axillary lymph nodes of 3 patients (8). Furthermore, Khanna et al (14) reported 52 cases of BTB within a 15-year period, which accounted for 3% of all breast lesions reported at their hospital. The authors reported presence of a breast mass with associated sinus in 39% of cases, isolated breast lump in 23% of cases, sinus with absence of a lump in 12% of cases and tender nodules in 23% of cases, with associated axillary lymphadenopathy reported in 41% of cases. The BTB diagnosis was confirmed using FNAC or histological examination in all the patients, and the main treatment administered was anti-TB therapy (14). Another study by Al-Marri et al (6) reported 13 multiparous women with BTB within a 10-year period, who were diagnosed based on histological examination. All patients presented with a mass, while 2 patients had symptoms of nipple discharge and 1 presented a palpable axillary node on the same side (6). Ben Hassouna et al (15) reported 65 BTB cases, which represented 0.2% of the tubercular localizations and 0.3% of the breast pathologies reported at their clinic within the investigated time period. The initial suspected diagnosis was malignant tumor in 60% of the BTB cases, benign nodule in 24.6% of patients and presence of an abscess in 16.4% of patients (15). Based on mammography examination, a malignant lesion was suspected in 49% of cases, while FNAC was performed in 8 patients, showing a negative result in 6 of these (15). Eventually, the BTB diagnosis was established using histological examination following identification of typical TB lesions on tumorectomy or biopsy samples, and all patients received anti-TB treatment (15). A study by Harris et al (16) evaluated 38 patients with BTB reported over a 5-year period, with a mean age of 29 years. Of these, 10 patients (26%) experienced breast pain with or without increased breast nodularity, while 14 patients (36%) presented axillary lymph node involvement (16). Associated pulmonary TB was only identified in 5/38 patients, with the remaining presenting isolated involvement of the breast (16). Patients were mainly treated with anti-TB drugs for 6–9 months (16).

In an earlier study by Sharma et al (17), 7 females with BTB were diagnosed between 1980–1988, with an age range of 17–50 years. The clinical features included lumps, ulcers, multiple discharging sinuses and recurring abscess of the breast. Diagnosis was established based on histological examination results, while AFB positivity was found in only 1 samples and positive culture in 1 other patient. Patients received anti-TB treatment along with removal of the infected breast tissue (17). Fukuoka et al (18) reported 12 BTB cases within a 10-year period, with a mean age of 42.8 years (range, 28–84 years). Only 1 case had past history of TB contact and in the remaining cases TB of the breast was considered to be a primary disease. Axillary lymph node involvement and formation of pyogenic breast abscess occurred in 7 cases. The histological findings revealed epithelioid cell granulomas with caseous necrosis in 11/12 cases, and 7/11 cases were treated with a combination of surgery and anti-TB chemotherapy (18). Furthermore, Morsad et al (19) treated 14 BTB cases at their hospital over a 16-year period, with patient ages of 16–65 years. Contact with TB was reported in 2 cases, and axillary nodes were observed in 10 cases. The diagnosis of BTB was based on pathological findings in 14 cases (including 2 biopsies and 12 perioperative specimens) and isolation of bacilli from pus in 1 case. Medical treatment was provided, as well as surgery when required, for abscess drainage or treatment of residual lesions (19).

In conclusion, BTB is a rare form of TB and the present retrospective study reported 7 cases of BTB along with the results of histopathological examination, microbiological examination and treatment. TB must be considered when there is presence of breast masses presenting with tenderness, pain, swelling and fluctuation in abscess formation, with or without discharging sinuses.