Radiologic findings of idiopathic granulomatous mastitis

To describe the radiological findings of idiopathic granulomatous mastitis (IGM).

Radiologic findings of 30 women with histopathological diagnosis of IGM were retrospectively evaluated. All had breast feeding history. All the patients had ultrasonography (US), with 12 of them having additional Doppler US. Of 30 patients, 11 had mammography (MG) and 5 MRI.

US showed multiple irregular hypoechoic masses and collection areas with tubular connections in 25 of 30. The collection area with low-level internal echoes but without tubular connections, suggesting an abscess were seen in 2 of 30 (6.6%); a hypoechoic mass with an indistinct border in 2 of 30 (6.6%); multiple milimetric hypoechoic nodular masses in 1 of 30 (3.3%). On MG, normal findings were noted in 5 (45.4%); focal asymmetric density in 4 (36.4%), parenchymal distortion in 1 (9%) and diffuse asymmetric opacity with trabecular thickening in 1 (9%) of 30 patients. On MRI, segmental T2 hyperintensity with contrast-enhancement on T1 were seen in 4 of 5 (80%). An enhancing T2 hypointense mass with irregular margin was present in 1 of 5 (20%). Time-signal intensity curve of lesions showed slow enhancement in 1 and moderate in 4 of 5 patients.

In IGM, MG findings were nonspecific. In US, multiple irregular hypoechoic masses and collections with tubular connections with fingerlike aspects, and fistulae formation to the skin in patients with breastfeeding history suggested IGM rather than carcinoma. Due to the limited number of patients, no conclusion was reached regarding MRI of IGM.