Granulomatous diseases of the breast and axilla: radiological findings with pathological correlation

Insights Imaging Granulomatous diseases of the breast and axilla: radiological findings with pathological correlation Jeffery E. Illman 0 1 Simone B. Terra 0 1 Allison J. Clapp 0 1 Katie N. Hunt 0 1 Robert T. Fazzio 0 1 Sejal S. Shah 0 1 Katrina N. Glazebrook 0 1 0 Sanford Broadway Clinic , Fargo, ND , USA 1 Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, MN , USA 2 Katrina N. Glazebrook Objectives This article reviews our experience and describes the literature findings of granulomatous diseases of the breast and axilla. Methods After approval of the Institutional Review Board was obtained, the surgical pathological records from January 2000 to January 2017 were searched for the keyword granulomatous. Clinical, imaging and histology findings were reviewed by both a fellowship-trained radiologist and a breastimaging consultant radiologist, reviewing 127 patients (age range, 32-86 years; 126 women and 1 man). Results Most common causes of granulomatous lesions of the breast and axilla included silicone granulomas 33% (n = 42), fat necrosis 29% (n = 37) and suture granulomas 11% (n = 14). In 16% (n = 20), no cause could be found and clinical history was consistent with idiopathic granulomatous mastitis. Other granulomatous aetiologies included granulomatous infections, sarcoidosis and Sjögren's syndrome. Causes of axillary granulomatous disease were similar to the breast; however, a case of cat-scratch disease was found that only involved the axillary lymph nodes. They can have a variable appearance on imaging and may mimic malignancy with irregular masses seen on mammography, ultrasound and magnetic resonance imaging. Fistulas to the skin and nipple retraction can suggest chronicity and a granulomatous aetiology. Breast; Granulomatous mastitis; Mammography; MRI; Ultrasonography - Department of Radiology, Mayo Clinic, Rochester, MN, USA Introduction With Institutional Review Board approval, a search of the surgical pathology records of approximately 17,000 breast biopsies performed at our institution from 1 January 2000 to 1 January 2017 yielded 127 patients (age range, 32– 86 years; 126 women and 1 men) with granulomatous disease of the breast, and their imaging results were available for review by both a fellowship-trained radiologist and breast-imaging consultant radiologist. The search found records of 42 silicone granulomas, 37 fat necrosis, 20 idiopathic granulomatous mastitis, 14 suture granulomas, 1 Corynebacterium, 1 Mycobacterium fortuitum infection, 2 sarcoidosis and 1 Sjögren’s syndrome. Additionally, nine cases of granulomatous lymphadenitis where found: six of which were secondary to granulomatous causes involving the breast (for example, silicone granuloma), one was idiopathic and one patient was diagnosed with cat-scratch disease. A granuloma is the human immune system’s way of Bwalling off^ an offending impurity, be it a foreign body, chronic infection or necrotic fat. A granuloma (Fig. 1) is an organised group of macrophages (mononuclear cells within tissue) associated with a variable amount of lymphocytes. The outer layer of the granuloma consists of lymphocytes, fibroblasts and vessels. Granulomas may also contain additional cells such as neutrophils, eosinophils and fibroblasts, which can provide a clue to the aetiology of the granuloma. Central necrosis may also help determine the cause of the granuloma; infectious granulomas tend to have central necrosis, termed necrotising granulomas (Fig. 1). Central necrosis with a cheese-like appearance has been termed caseating necrosis and is a feature of Mycobacterium tuberculosis infection. A non-caseating granuloma (Fig. 1) can occur with non-infectious causes such as sarcoidosis. Imaging findings can have a variable appearance and may mimic malignancy with irregular masses on mammography, ultrasound and magnetic resonance imaging (MRI), requiring biopsy. The diagnosis can be suggested if correlation is made with clinical history. This article reviews and illustrates the salient imaging features of granulomatous processes of the breast and axilla, including infectious, traumatic, autoimmune, as well as unknown causes (Fig. 2). Infectious causes Most breast infections are bacterial and are usually secondary to skin contamination, with most infections resolving without sequela. Specialised stains are occasionally necessary for specific diagnosis, including Gram, periodic acid-Schiff and Ziehl-Neelsen stains. Overall, chronic infections with granulomatous reactions are rare and a high index of clinical suspicion is necessary. Clinical Clinically patients present with a painful and/or palpable breast mass, often with axillary lymphadenopathy. A discharging sinus tract can be seen if treatment is delayed. The subareolar regions may be relatively spared. Reactive lymphadenopathy may be present in up to 15% of cases. Mammography Imaging features are variable depending on type of infection, but are unable to re (...truncated)