Tuberculous mastitis diagnosed on cytology - case report of a rare entity.

Tuberculous mastititis is a rare clinical entity and usually affects women from the Indian subcontinent. It often mimics breast carcinoma and pyogenic breast abscess. Fine needle aspiration cytology (FNAC) is a very essential diagnostic tool when other routine laboratory investigations are not helpful in reaching to the conclusion. Tuberculosis (TB) of the breast is an uncommon presentation of TB even in countries where the incidence of pulmonary and extrapulmonary TB is high. Radiological imaging is not diagnostic.

Introduction

Tuberculosis (TB) of the breast is relatively a rare occurrence, with the reported incidence varying from 3–4.5% in developing countries such as India.[1] Extrapulmonary TB is on the rise, the world over. TB of the breast has no defined clinical features. The multifaceted presentation of this disease is often confused with either breast abscess or carcinoma of the breast, both clinically and radiologically.[2] Several Indian series reported the incidence of breast TB among the total number of mammary conditions to vary from 0.64–3.59%.[3] Less than 100 cases of mammary TB were reported from India till 1987[4] and only 500 cases were documented from the world medical literature by Hamit and Ragsdale in 1982.[5] The first 13 cases of breast TB from India were reported by Chaudhary in 1957 from 433 breast lesions studied by her.[6]

Case Report

A 27-year-old female, with a history of lactation, presented to the cytology section, Department of Pathology, in a tertiary care center, with chief complaints of lump in the right breast and history of lactation. On examination, there was a tender, ill-defined, irregular lump in the right breast. Nipple, areola, and overlying skin were normal. There was no axillary or cervical lymphadenopathy. Clinical examination revealed anemia (hemoglobin 8.1 g%) and raised erythrocyte sedimentation rate (ESR) (88 mm 1st h). A clinical diagnosis of fibroadenoma was entertained and fine needle aspiration cytology (FNAC) was done using a 22 gauge needle with a 10 mL syringe. Approximately 2 mL of the pus was aspirated. Smears were air dried and alcohol-fixed for May-Grunwald-Giemsa (MGG) and hematoxylin and eosin (H and E) stains respectively and additionally with Ziehl-Neelsen (ZN) stain for acid fast bacilli (AFB).

On microscopy, smears showed the presence of occasional clusters of ductal cells in a background of caseous necrosis which was typically acellular, amorphous, and granular with the loss of cellular details [Figure 1a and b]. However, no typical epithelioid granulomas were seen. It was the presence of this caseous necrosis that alerted us to the possible presence of a tubercular infection. In addition, neutrophils were scattered in the amorphous caseous necrotic material [Figure 1c]. ZN stain for AFB revealed the presence of AFB [Figure 1d] and a provisional diagnosis of tuberculous mastitis was made.

Figure 1

(a) Photomicrograph showing benign ductal epithelial cells (arrow) along with area of caseous necrosis (MGG stain × 40). Inset showing benign ductal epithelial cells arranged in glandular fashion (MGG stain × 400) (b) Photomicrograph showing amorphous caseous necrosis (H and E × 100) (c) Photomicrograph showing amorphous caseous necrosis along with polymorphonuclear cells (H and E stain × 400) (d) Photomicrograph showing acid-fast bacillus (ZN stain × 1000)

A repeat fine needle aspiration (FNA) was done and the aspirated material was sent for culture and sensitivity to the Department of Microbiology of the tertiary care center. The culture report confirmed the diagnosis of tuberculous mastitis.

Discussion

TB of the mammary gland is a rare disorder often mistaken for other benign and malignant lesions of the breast. The first case of mammary TB was recorded by Sir Astley Cooper in 1829, who called it “Scrofulous swelling of the bosom.”[7] Hamit and Ragsdale in 1982 documented only 500 cases of tuberculous mastitis, from world medical literature.[5] Since then, case reports and reviews are being published to highlight the diagnostic dilemma of the disease. However, mammary TB is comparatively less common than carcinoma of the breast.

FNAC has become the first choice as a diagnostic procedure in a variety of breast diseases. This technique can be sucessfully used to diagnose caseating granulomas in breast aspirates as well as to demonstrate AFB. Nipple discharge, if present, should be screened for TB as well.

The breast tissue is remarkably resistant to tubercular infection. This is due to the fact that like the skeletal muscles and the spleen, the mammary tissue too provides an infertile environment for the survival and muliplication of tubercle bacilli.[34] It occurs more frequently in females especially in their reproductive age (21–30 years) and is uncommon in prepubescent and elderly women.[5] In pregnant and lactating women, the breast is more vascular with dilated ducts. This increased vascularity of the breast may facilitate infection and dissemination of bacilli.[14] Shinde et al.[1] and Banerjee et al.[4] found in their studies that 7% and 33% of their patients respectively were lacatating at the time of presentation. Additionally, the lacatating breast is susceptible to trauma, making it more predisposed to tubercular infection.[14] Bilateral disease is rare, occuring in 3% of the patients.[5]

Breast TB may be considered primary when no other demostrable focus exists, and may be considered secondary when a preexisting lesion is located elsewhere.[8] Our case was a primary case of TB of the breast. Mckeown and Wilkinson [8] classified breast TB as primary when the breast lesion was the only manifestation of TB, and secondary when there was a demonstration of TB elsewhere in the body. Breast TB was originally classified by Mckeown et al. into the following categories: (a) Acute miliary tuberculous mastitis—rare, due to blood borne infection in military TB; (b) Nodular tuberculous mastitis—the most common type, which presents as a localized lump with or without sinuses in one quadrant of the breast; (c) Disseminated or confluent tuberculous mastitis—involving the entire breast with multiple sinuses; (d) Sclerosing tuberculous mastitis—minimal caseation and extensive hyalinization of the stroma, shrinkage of the breast tissue with early skin retraction, and late sinus formation; clinically, this type is indistinguishable from carcinoma; and (e) Tuberculous mastitis obliterans—a rare form due to intraductal infection with fibrosis and obliteration of the ductal system; sinus formation is infrequent.[8] Our case fulfilled the criteria of nodular variety, similar to the study by Mukherjee et al.[3] The most common symptom is a lump in the breast along with pain that was present in our case. Pain is usually not a feature in cases of carcinoma.

The demonstration of AFB on FNAC is not mandatory, because the number of AFB must be 10,000–100,000/mL of material to be seen microscopically.[3] The demonstration of AFB from the lesions is usually difficult, although it was demonstrated in the present case.

The breast may become infected in a variety of ways (1) hematogenous, (2) lymphatic, (3) direct inoculation, (4) ductal infection, (5) skin abrasions, and (6) duct openings of nipples. Of these, the most accepted view of spread of infection is via the centripetal lymphatic spread.[3] The path of spread of the disease from the lungs to the breast tissue was traced via tracheobronchial, paratracheal, mediastinal lymph trunk, and internal mammary nodes.[8]

At times, the FNAC picture may be diverse. It may be inflammatory (both lymphocytes and polymorphs) or reveal a large number of polymorphs with necrotic material,[9] as was seen in our case. In our case as well, the cytopathology picture revealed polymorphs along with necrosis and AFB. In cases where the necrosis is extensive, chances of finding epithelioid granulomas are rare. In a country such as India, where TB is endemic, the presence of necrosis, even in the absence of AFB, should alert one to the diagnosis of TB. The commonest cause of caseation in developing countries such as India is TB. The detection of caseous material in cytology smears depends on the experience of the pathologists.

Though mycobacterial culture remains the gold standard for the diagnosis of TB, the time that is required, and the frequent negative results in paucibacillary specimens are important limitations.[10]

Conclusion

The significance of breast TB is due to its mistaken identity with breast cancer and pyogenic breast abscess. FNAC (a well-established diagnostic modality) in such cases prevents delay in the institution of specific therapy and subsequent complications of the disease. The importance of doing acid-fast stain in suppurative aspirates of the breast is highlighted in our case. The presence of AFB in the smears is confirmatory for the diagnosis of TB and for institution of specific therapy and to avoid subsequent complications of the disease.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.