Idiopathic Granulomatous Mastitis a Rare Entity Often Masquerading as Carcinoma: Report of 6 Cases.
Dana Jaggessarsingh, Philip H Kane, Clifford Bernstein, Meenakshi Singh, Patricia Farrelly, Brian O'Hea, Carmen Tornos. Stony Brook University Medical Center, NY
Background: Idiopathic granulomatous mastitis (IGM) is a rare benign entity of unknown etiology that occurs in women of childbearing age and can mimic infection or malignancy clinically and radiologically. Some authors have suggested an immunologic pathogenesis. The diagnosis is based on exclusion of malignancy, infectious and other granulomatous processes, and histopathologic confirmation is necessary Because of its low prevalence (2.4 per 100,000 women aged 20-40 years) many physicians are not familiar with this entity. We report our experience with 6 cases seen at our institution.
Design: Six cases identified between 1997 and 2010 were retrieved from our pathology files. Clinical details and follow up were obtained from the patients' charts and from the contributing surgeons and radiologists. H&E stained sections and special stains for micro-organisms were re-examined in all 6 cases.
Results: The mean age of the patients was 35 years (range 21 – 50 years). Clinical presentation included palpable breast masses in 5 cases, and swelling and discomfort in 1 case. The lesion was unilateral in all cases. One patient was lactating at the time of presentation, and 4 patients were 4 to 48 months post partum. The lesion was clinically suspicious for malignancy in 3 cases. Imaging studies were suspicious for malignancy in 3 patients, and one had a suspicious axillary node on MRI. Two cases underwent core biopsy and 4 cases surgical excision. All cases had similar histologic findings: abundant non-necrotizing granulomata, centered around lobules with associated chronic inflammation. In 1 case the granulomata were confluent and involved the entire lobule. Microabscesses were seen in 3 cases. A thin layer of neutrophils circumferentially surrounding a centrally located empty lumen was seen in 3 cases. All cases had negative stains for acid fast bacilli and fungi, and one case had negative PCR for AFB. Other causes of granulomatous inflammation were excluded in all cases including other infections, sarcoidosis, foreign body material, previous surgery/instrumentation, and trauma.
Conclusions: IGM is a rare entity that causes non-necrotizing granulomatous inflammation of the breast predominantly in young women, and can mimic malignancy clinically and radiologically. Correct diagnosis requires the exclusion of other granulomatous causing processes. Greater awareness of this entity will help making timely and accurate diagnosis.
Monday, February 28, 2011 1:00 PM
Poster Session II # 60, Monday Afternoon