1. Radiologic Features of Idiopathic Granulomatous Mastitis Z. ACHOUR 1, H. EL MHABRECH 1, A. KHELIFFI 1, E. BEN SALEM 1, A. HADDAD 2, CH. LOUSSAIF 3, C. HAFSA 1 Radiology Service, CMN Monastir Tunisia

2. INTRODUCTION: Idiopathic granulomatous lobular mastitis,or idiopathic granulomatous mastitis (IGM), is a rare chronic inflammatory lesion of the breast that can clinically and radiographically mimic breast carcinoma.

3. purpose: The aim of this study is to describe the radiological imaging features of IGM in order to better differentiate this disorder from breast cancer.

4. MATERIALS AND METHODS We performed a retrospective analysis of the clinical and radiographic features of 7 women with a total of 7 IGM lesions. The ages of these women ranged between 30 and 48 years. The chief clinical complaint was: breast mass in 4 cases and inflammatory mastitis in 3. All patients were examined by both mammography and sonography.

5. RESULTS: A 37 year-old female, gravida 6 para 3 consulted for a right breast mass A mammogram was realised and concluded to an increased density of the upper lateral quadrant of the right breast. US hypoechoic area with low decreased acoustic shadowing. The patient undrwent a surgical excision and pathology showed IGM

6. b a US: irregula tubular lesions Lateral mammogram of a 34- year-old female patient with a huge idiopathic granulomatous mastitis. Note the presence of a vague increased density of the left breast in the absence of a discrete mass or suspicious micro- calcifications.

7. A 48 year-old female, gravida 5 para 3 consulted for a right breast mass. A mammogram was realised and concluded to an increased density of the lower lateral quadrant of the right breast. US hypoechoic mass with low decreased acoustic shadowing.

8.  A 48 year-old female,gravida 4 para 3, was admitted to the hospital for a recurrent breast abscess. Mammography revealed an opacity of the lower medial quadrant of the right breast. US an important galactophoric ectasia with an echogenic conten. The patient undrwent a surgical excision and pathology showed IGM with multinucleated giant cell and chronic lobulitis

9. Malignancy was suspected in all patients and fine needle biopss was performed in all cases cofirming the diagnosis of IGM

10. DISCUSSION:

11. Idiopathic granulomatous lobular mastitis, or idiopathic granulomatous mastitis, is a rare chronic inflammatory lesion of the breast that can clinically and radiographically mimic breast carcinoma. IGM was first described by Kessler and Wolloch in 1972. This disorder is characterized by the chronic granulomatous inflammation of lobules without caseous necrosis IGM is of unknown origin, and its diagnosis rests on both the demonstration of a characteristic histological pattern and the exclusion of other possible causes of granulomatous breast lesions.

12. Although the exact etiology of IGM remains unclear, associations with autoimmune disorders, oral contraceptive use, pregnancy, hyperprolactinemia and alpha-1-antitrypsin deficiency have been suggested. Most studies report an average age of presentation in the third decade of life (range 11 to 83 years) with symptoms often developing within a few years of pregnancy. Moreover, conflicting data exists regarding the significance of oral contraceptive use in patients diagnosed with IGM.

13. The diagnosis of IGM rests on the documentation of a characteristic histologic pattern, combined with the exclusion of other possible causes of granulomatous lesions of the breast.

14. IMAGING ASPECTS: Mammography and ultrasonography are used mainly to rule out malignancy rather than confirming the diagnosis of IGM +++.

15. Mammographic features of granulomatous mastitis  The reported mammographic features of granulomatous mastitis are :  An asymmetric density with no distinct margin or mass effect: asymmetric density is a non-specific mammographic finding that could be seen in clinically normal breasts or in other various disease types.  Irregular ill-defined masses.

16.  Diffuse increased density.  Oval obscured masses in young women with Heterogeneously dense breast.  Calcifications in rare cases.  Benign-looking axillary lymph node enlargements.  Skin thickening.  Patients with dense breast parenchyma may also have negative mammograms.

17. US FEATURES:  Multiple clustered, often contiguous, tubular hypoechoic lesions.  Hypoechoic mass.  Tubular hypoechoic areas connecting to a mass.

18.  Irregular lobulated masses  Parenchymal distortions without definite mass.  Unusual Us finding of a focally decreased parenchymal echogenicity and acoustic shadowing.  Subcutaneous fat infiltration is minimal indicating that the findings were not acute infection

19. MRI ASPECTS: o The Gd-DTPA-enhanced dynamic MRI shows that IGM is associated with progressive enhancement, which could be smooth or irregular, with foci showing peripheral ring shaped contrast enhancement pattern, with delayed washout. o Such an enhancement pattern can mimic those of inflammatory processes, a proliferative dysplasia, and neoplasm.

20. o The real value of MRI might be in saving some patients unnecessary surgery if an inactive lesion, such as fibrosis or fat necrosis, is present. o Such lesions, clinically and mammographically, resemble carcinoma, but would not produce active MRI enhancement pattern encountered in tumoral or inflammatory processes.

21. TREATMENT: o The optimal treatment for GM has yet to be established. Surgical resection of the affected tissue, with or without corticosteroid therapy, has often been the current method of treatment. o However, with these treatments, a tendency for local recurrences and delayed wound healing exists.

22. CONCLUSION: Clinical information and radiographic features of GM may aid in the differentiation between IGM and early onset breast cancer. However, a histological confirmation is still required for a positive diagnosis and the determination of an appropriate treatment regimen.