What is the diagnostic approach for a female patient of reproductive age with suspected tuberculosis (TB) mastitis, particularly from a region with high TB prevalence or with a history of TB exposure?

Diagnostic Approach for TB Mastitis

TB mastitis should be diagnosed through a combination of clinical suspicion based on epidemiologic risk factors, fine needle aspiration or excisional biopsy with histopathology demonstrating caseating granulomas or acid-fast bacilli, and confirmation via PCR or mycobacterial culture, as radiological and clinical features are non-specific and frequently mimic breast cancer or pyogenic abscess. 1, 2

Clinical Presentation and Initial Suspicion

TB mastitis presents most commonly as a unilateral breast mass mimicking breast cancer (70% of cases) or as a breast abscess (20-30% of cases), with additional features including skin sinuses, nipple retraction, and axillary lymphadenopathy 1, 3. The disease predominantly affects parous women of reproductive age (mean age 32.9 years), with 20-30% occurring during lactation or pregnancy 1, 2.

Key Epidemiologic Risk Factors to Elicit:

• History of prior pulmonary TB (present in 20-30% of cases) 1, 3
• Origin from or residence in TB-endemic regions (particularly South Asia and Africa) 4, 5, 2
• Family history of TB exposure 5
• HIV infection or other immunosuppression 2

Diagnostic Algorithm

Step 1: Initial Clinical and Radiological Assessment

Perform bilateral mammography and breast ultrasound, recognizing that findings are non-specific and cannot distinguish TB from malignancy 3, 2:

Mammographic findings (none are diagnostic):

• Mass lesions mimicking malignancy with irregular borders (30%) 3
• Smooth-bordered masses (40%) 3
• Axillary or intramammary lymphadenopathy (40%) 3
• Asymmetric density (30%), duct ectasia (30%), skin thickening (20%), macrocalcifications (20%) 3

Ultrasound findings:

• Hypoechoic masses (60%) 3
• Focal or sectorial duct ectasia (40%) 3
• Axillary lymphadenopathy (50%) 3

Step 2: Obtain Chest Radiograph

Order chest X-ray to evaluate for concurrent pulmonary TB, which is positive in 20% of TB mastitis cases 3. This aligns with general TB diagnostic principles that recommend chest radiography in all suspected TB cases 6, 7.

Step 3: Tissue Diagnosis (Essential)

Fine needle aspiration (FNA) should be performed initially on all breast masses, followed by excisional biopsy if FNA is non-diagnostic 1, 2. The diagnosis of TB mastitis is established through:

Primary diagnostic methods:

• Histopathology demonstrating caseating granulomas with or without Langhans giant cells (diagnostic in majority of cases) 1, 2
• Demonstration of acid-fast bacilli (AFB) on Ziehl-Neelsen or Auramine-O staining of tissue specimens (positive in only 20-30% of cases) 1, 7
• PCR testing on tissue specimens when histology is suggestive but AFB staining is negative (essential for culture-negative cases) 1, 3, 5

Gold standard confirmation:

• Mycobacterial culture of tissue specimens for definitive species identification and drug susceptibility testing 6, 7, 8

Step 4: Additional Testing in High-Risk Patients

In patients from TB-endemic areas or with TB exposure history, consider:

• Interferon-gamma release assay (IGRA) such as QuantiFERON to support diagnosis, particularly in culture-negative cases 6, 5
• Note: IGRA and tuberculin skin testing cannot diagnose active TB disease but may support clinical suspicion 8

Critical Diagnostic Pitfalls

Do not rely on imaging alone – mammographic and sonographic features are non-specific and frequently mimic breast carcinoma, leading to delayed diagnosis (average 14 months in some cases) 4, 3, 2.

Culture-negative TB mastitis is common – most cases (70-80%) are culture-negative, requiring diagnosis based on histopathology combined with PCR 1, 5, 2. This parallels the general principle that 40% of culture-positive pulmonary TB cases are smear-negative 8.

Always obtain tissue for culture before initiating treatment to enable drug susceptibility testing, even when empiric therapy is started based on high clinical suspicion 6, 8.

When to Initiate Empiric Treatment

Start empiric anti-tuberculous therapy in patients with:

• Histopathology showing caseating granulomas 1, 5
• High clinical suspicion based on endemic origin, TB exposure history, and positive IGRA 5
• Refractory mastitis or breast abscess not responding to conventional antibiotics 4, 5

The standard 6-month regimen (isoniazid, rifampin, pyrazinamide, and ethambutol for 2 months, followed by isoniazid and rifampin for 4 months) is adequate for TB mastitis, with conservative surgery reserved for severe breast destruction 1, 2, 7, 8.