Primary breast actinomyces simulating malignancy: A case diagnosed by fine-needle aspiration cytology.

We report a case of primary actinomycosis of breast diagnosed by fine needle aspiration cytology (FNAC) in a postmenopausal lady who presented with a clinical impression of malignancy. Resolution of infection while conserving the breast was achieved by timely diagnosis and effective antibiotic therapy. The literature reports that primary actinomycosis of the breast is very rare after menopause, with only very few cases found after extensive search. It is imperative that this condition should be considered in the differential diagnosis of malignancy. The effectiveness of cell block sections in the final diagnosis is also highlighted.

Introduction

Actinomycosis is an indolent, slowly progressive infection caused by anaerobic or microaerophilic bacteria, from the genus Actinomyces, which colonize the mouth, colon and vagina. The disease is characterized by abscesses with draining sinus tracts discharging sulphur granules composed of branched filaments. Primary actinomycosis of breast is a rare disease, with less than 32 cases reported since its first description by Ammentorp in 1893.[1-3] Breast actinomycosis is primary when inoculation occurs through the nipple. Secondary actinomycosis of the breast is the extension of pulmonary infection through the thoracic cage.[23] Breast actinomycosis may present as sinus tract or mass mimicking malignancy. The clinical presentation makes it difficult to distinguish primary actinomycosis from mastitis and inflammatory carcinoma.[3] Infection does not require predisposing diseases and can occur in healthy individuals.[1] Most often diagnosis is made after surgery and biopsy. Here we present a case of primary actinomycosis in a postmenopausal lady as mass in the left breast of 6-month duration. Clinical findings were suggestive of malignancy and mammography suggested an inflammatory lesion. This case is unique because diagnosis was made by fine needle aspiration with cellblock study.

Case Report

A 61-year-old diabetic woman presented with a mass in her left breast of 6 months duration. There was no history of fever, lung disease, tooth problems, facial skin lesions, tonsillitis, gingivitis or breast trauma.

On physical examination there was an indurated subareolar mass of 5×6 cm size with skin fixity in the left breast. No draining sinuses or lymphadenopathy were noted. She was afebrile and appeared otherwise healthy. Chest radiograph appeared normal. Mammogram was suggestive of an abscess. With the clinical suspicion of malignancy, fine needle aspiration cytology (FNAC) was advised.

On obtaining informed consent, the patient was taken for FNAC. Repeated aspirations yielded only pus. Smears showed collections of neutrophils, histiocytes and fluffy fine areas and were negative for malignant cells [Figure 1a]. A diagnosis of chronic suppurative inflammation was made. The patient was already on antibiotics. The cell block sections later showed a similar inflammatory reaction and few colonies suggestive of actinomycosis [Figure 1b]. Diagnosis was confirmed by Grams stain and cell block stained with Grocott- Gomori methenamine-silver nitrate stain which showed positive filamentous branching bacteria [Figure 2]. The colonies were stained negative with Ziehl-Neelsen stain. Repeat aspirations were done for aerobic and anaerobic cultures; which turned out to be negative, perhaps because of previous antibiotic treatment given to the patient. The patient was given full course of antibiotics and on follow-up she is doing well.

Figure 1

(a) Photomicrograph of aspirate showing mixed inflammatory cell exudates and fluffy colonies (Giemsa, ×100), (b) Cell block section showing actinomycotic colony surrounded by inflammatory infiltrate (H and E, ×100)

Figure 2

(a) Cell block section showing positive silver impregnation of actinomycotic colonies (GMS, ×400), (b) Photomicrograph showing Gram-positive branching filamentous bacilli (Gram stain, × 400)

Discussion

Actinomycosis is a subacute to chronic, suppurative, granulomatous disease that tends to produce draining sinus tracts. It is caused by Gram-positive anaerobic filamentous bacteria that are part of the normal oral flora. The most frequent cause is A. israelii, present in 78% of patients. Actinomycosis is a chronic infection that drain sulphur granules which represent bacterial colonies that appear microscopically as intertwined radiating filaments (rays) terminating in pear-shaped “clubs”. With sulphur granules in the appropriate clinical setting; a diagnosis of actinomycosis can be made with high degree of certainty.[4] The main clinical forms of actinomycosis are cervicofacial, thoracic, abdominal and in women pelvic. Dissemination to other organs may occur by spatial contiguity. The disease is four times more common in men; usually the patients are in otherwise good health, with no associated diseases.

Primary actinomycosis of the breast commonly involve premenopausal women.[1-35] Our case is a postmenopausal woman which is rare with only very few cases reported in literature.[23]

The disease usually starts at the nipple. Most cases are recurrent abscesses often retropapillary. Fistulas and purulent or bloody discharge from sinuses may occur. In advanced cases, fibrosis with local cicatrization and architectural distortion of the breast tissue occur. Moreover, there may be dissemination to other organs. It is important to exclude chronic suppurative mastitis, tuberculosis, syphilis, and chronic osteomyelitis of the ribs. Another rare clinical presentation is a mass lesion mimicking malignancy; so was our case.

Possible causes of this condition are trauma, lactation and kissing.[2] The most commonly isolated pathogen has been A. israelii. In recent years, other strains have been found as well. There are isolated case reports of primary actinomycosis of the breast caused by A. viscosus, A. turicensis and A. radingae. Microbiological identification of the agents occurs only in a minority of cases.[45]

The diagnosis is made by histopathological examination of biopsied material. FNAC and image-guided aspirations are being successfully used to obtain material for diagnosis.[4] Grocott-Gomori silver stain, Grams and Ziehl- Neelsen stain together helps in establishing the diagnosis.[23] Culture yields positive results in only 50% of patients and should be performed with both aerobic and anaerobic media.[4] Usually there are abundant granules, but only a single granule was identified from 26% of specimens in one large series. The presence of granules composed of actinomycotic colonies and showing a characteristic appearance establishes the diagnosis when culture is unsuccessful or suitable specimens for culture are not available.[4] Even a single dose of antimicrobial therapy can interfere with their isolation.[34] Grams stain is more sensitive than culture in this setting. When fine-needle aspiration cytology of apparently malignant masses yields only chronic inflammation, actinomycosis should also be considered in the differential diagnosis. We highlight the need to keep cellblock for pus aspirated from chronic abscesses for serial sections and histochemical stains.

The relevance of this case report is that primary breast actinomycosis is a rare lesion in a postmenopausal woman where the diagnosis was made on cytology.[36] The use of cell block studies in breast abscesses presenting as mass lesion is highlighted. Distinguishing breast actinomycosis from tuberculosis and other potential infectious conditions is possible through pathological examination. Diagnostic accuracy of FNAC is very high and is recommended as an early diagnostic procedure in palpable breast lesions, thereby avoiding unwanted surgeries.[5]