An abscess or a painless breast lump may indicate rare extrapulmonary TB. This disorder includes both the primary and secondary subgroups. The rare primary form is breast-only tuberculosis (TB). Primary tuberculous foci such as the lungs, pleura, and lymph nodes are related to the more common secondary form. Even in endemic areas, low clinical suspicion and similarity to other diseases make TM diagnosis difficult. TM can be diagnosed by a qualified surgeon, radiologist, or pathologist. In this study, during January 2024 we had 4 women in their perimenopausal diagnosed with tuberculous mastitis. The average age of the patients was 28.75 (24–41 years). One patient was diagnosed during pregnancy, and one had a history of prior breastfeeding. The findings for all patients are summarized in Table 1.

TM usually affects women of reproductive age, likely due to the hypervascularization of breast tissue and widening of lactiferous ducts during this period. ¹² However, TM is also found in adolescent girls, elderly women, and men. ¹³ Multiparity, lactation, and pregnancy are known risk factors for the development of breast tuberculosis. ^{14 , 15} A case series of 32 cases reported that 12.5% of all their cases were pregnant and lactating women. ¹² Lactation causes breasts to be vulnerable to trauma, making it easier for pathogenic bacteria to infect the tissue, especially if Mycobacterium tuberculosis is present in the baby’s faucial tonsils, which is suspected to be a potential route of infection in mothers. ^{12 , 16} Lactation makes the breast highly vascularized and ducts dilated, making newborns and multiparous women more susceptible to TB. Pregnancy suppresses the pro-inflammatory T-helper response, which may enhance the tendency toward infection, as breast TB symptom presentation usually lasts less than a year but can last months or years. ¹⁷ Patients with TM often show symptoms for several weeks to months before diagnosis, with varying durations, but often less than one year. ^{13 , 16} In our findings, patients began experiencing symptoms from 2 weeks to 2 months before being diagnosed with TM.

All the patients had previously received a BCG vaccine. BCG vaccination has a 37% efficacy rate in preventing all types of tuberculosis in children under 5 years of age and a 42% efficacy rate in preventing lung disease in children under 3 years of age. However, it does not offer protection to teenagers or people in intimate contact with the disease. ¹⁸ It is important to enhance the immune response against M.tuberculosis in order to provide long-lasting protection, particularly after infancy. ^{19 , 20} According to the World Health Organization (WHO) data, Indonesia ranks second in the world, with the highest number of TB cases. In 2021, the incidence of TB in Indonesia was 354 cases per 100,000 people. ²¹ Initially, it was believed that 60% of TM cases were caused by primary conditions; however, it is now believed that TM is almost always caused by secondary lesions in other parts of the body. The most common spread is retrograde lymphatic spread from the lung focus through the paratracheal and internal breast lymph nodes. Hematogenous spread and direct extension from adjacent structures are other routes of infection. ¹⁶ Primary TM is very rare because the breast parenchyma is not an ideal site for Mycobacterium tuberculosis. ²² Based on history taking, it can be established that the patient is likely to have primary TM. A patient reported a lump in the armpit area, which was discovered after a breast complaint. Extrapulmonary tuberculosis is often asymptomatic ²³ ; hence, it is probable that some of our patients had secondary TM.

The most typical sign of breast tuberculosis is a lump, typically in the upper outer or central quadrant of the breast, due to frequent spread from the axillary lymph nodes to the breast. The lump often shows irregular and poorly defined features, along with a firm texture. It may cause pain and can move or attach to the underlying skin or muscle. Furthermore, this condition can manifest as a solitary nodule, typically without the accompanying constitutional symptoms commonly seen in tuberculosis. ^{24 , 25} Nipple retraction, peau d’orange, and breast edema have also been reported. ^{8 , 26 , 27} This lump occasionally resembles a cancer. ^{17 , 25} The results showed that all patients complained of breast lumps with or without abscesses, the majority of which were painful, firm, and had unclear borders. However, the lumps in our patient were typically found in the inner area of the breast. Half of our patients were clinically suspected to have breast malignancy.

TM is often unilateral, but both breasts can be infected, although this is very rare, occurring in only approximately 3% of all cases. ^{16 , 28 , 29} Multiple lumps have rarely been reported in cases of TM. However, a recent case series report found multiple lumps in 35.3% of the cases. ¹² TM was first classified by McKeon and Sir Geoffrey Wilkinson into five categories: acute miliary, nodular, disseminated, sclerosing, and obliterative. ^{16 , 22} Nodular caseous inflammation is the most common type. This type presents symptoms such as non-vascular hypoechoic mass without pain, elongated shape, well-defined borders, slow growth, resembling fibroadenoma in the early stages of the disease, and usually develops into a fistula within the nipple-areolar complex or in the skin and very similar to cancer. ²²

Radiographic results of breast tuberculosis are vague. ³⁰ In our case, all patients underwent an ultrasound examination. Chest radiography did not reveal any abnormalities or signs of pulmonary tuberculosis infection. One patient in this case series underwent FNAB examination with a diagnosis of breast carcinoma before arriving at our hospital. However, after re-examination, a diagnosis of tuberculosis mastitis accompanied by fibrocystic changes of Atypical Ductal Hyperplasia (ADH) type was made. Figure 8a shows breast tissue infested with acute inflammatory cells and chronic inflammation accompanied by necrotic areas. Langhan-type cells are visible (white arrows) between the connective tissue and hyperemic blood vessels. No visible signs of malignancy were observed. Figure 8b shows breast tissue showing chronic inflammatory cell-infested tissue (short black arrow) accompanied by necrotic areas. Necrotic breast glands (long black arrows) and Langhan-type data cells (white arrows) are visible between connective tissue and hyperemic blood vessels. No visible signs of malignancy were observed. Variations in diagnostic interpretation and reporting practices in anatomical pathology are not unusual. The percentage of inaccurate diagnoses ranges from 3% to 9%. ³¹ The lack of clear quality criteria for anatomical pathology laboratories as well as the objectivity of pathological anatomy specialists may have contributed to this inaccurate diagnosis. The second view lessens the need for modifications to the initial pathology reports and is a useful quality metric in anatomical pathology. ³²

In this series, TM presented with symptoms similar to those of breast cancer, such as ulceration, redness, a hard palpable lump with uneven borders, and an ultrasound examination that suggested a breast tumor. The gold standard examination for distinguishing it from breast cancer is histopathological investigation. Diagnosis of TM requires several specific tests. The Mantoux test does not provide a diagnosis but can confirm whether a patient has tuberculosis infection. Mammography is not always helpful for diagnosis, especially in young women, because of the density of breast tissue. However, mammography findings in elderly women cannot be differentiated from mammary carcinomas. Ultrasonography shows hypoechoic masses in 60% of patients, and this method can also detect fistulas or sinus cavities, which can be observed in tuberculosis cases. Computed tomography (CT) and Nuclear Magnetic Resonance (NMR) were used to assess the extent of the lesions outside the body, especially in the chest. The gold standard for diagnosing TM is to isolate M. tuberculosis in bacteriological cultures or to use the Ziehl-Neelsen stain. However, M. tuberculosis is present in one-fifth of TM cases. Acid-fast bacteria were found in less than 12% of patients. As a result, some authors concluded that a histological finding of granulomatosis accompanied by caseous necrosis is adequate for diagnosis. Fine-needle aspiration (FNA) is the most frequently used diagnostic procedure, with 73% specificity for identifying granulomatosis and caseous necrosis. In other investigations, FNA was frequently inconclusive, with a sensitivity of 28%, compared to 94% for histology. Acid-fast bacteria were detected in 10.3% of FNA specimens and in 29.7% of histological specimens. Some researchers discovered that FNA was able to diagnose TM in 18% of the cases. When FNA is ambiguous, obtaining a larger histologic sample may be recommended, especially if other breast illnesses such as carcinoma have to be ruled out. In addition, skin testing, interferon-gamma assays, imaging tests, biopsies, and PCR-TB can confirm diagnosis. ^{17 , 24 , 33} Polymerase Chain Reaction (PCR) is a highly sensitive method for the diagnosis of tuberculosis. Although popular, this method is only used in patients with negative culture results or other types of granulomatosis. Histopathological lesions identified chronic granulomatous inflammation with caseous necrosis and Langhans giant cells, contributing to the diagnosis in most cases. The main differential diagnosis for TM is breast carcinoma. Other differential diagnoses include fat necrosis, plasma cell mastitis, idiopathic granulomatous mastitis, and infections such as actinomycosis and blastomycosis. ^{13 , 16 , 28 , 34}

All of our patients received a 6-to-9-month course of anti-tuberculosis treatment. After one month of surgical excision, one person appeared with a breast ulcer and reported the presence of a pus-discharging lesion. We proceeded with the advanced stage of treatment till the ninth month. Debridement should be performed in this patient to enhance the efficacy of the treatment. All patients were reported to have achieved a complete cure of TM at the conclusion of their treatment.

Patients with tuberculous mastitis may present with nonspecific symptoms, although their condition may resemble that of mastitis or breast cancer. Due to the atypical symptoms presented by the patient, it is imperative to conduct comprehensive screening to rule out alternative probable diagnoses. The FNAC test is often regarded as the most dependable technique; however, false-negative results can still be obtained. Establishing a diagnosis requires effective teamwork between the attending physician, anatomical pathologist, and radiologist. Comprehensive research on a larger scale is required to accurately describe the existing situation.

This study was conducted using the primary patient data. Informed consent was obtained at the beginning of the patient’s visit by signing a letter of consent for examination, taking pictures, and publication for scientific purposes, and the patient’s identity was strictly protected. Written informed consent for publication of their clinical details and clinical images was obtained from the patient. The data collected were strictly used to achieve the research objectives.