Clinicorathologic Analysis Of Granulomatous Lobular Mastitis

Objective:To compare the differences of clinicopathologic features between Granulomatous lobular mastitis(GLM) and Mammary ductal ectasia(MDE). To investigate the etiology, clinicopathologic characteristics, diagnosis and treatment strategy of GLM.Methods:A total of118patients(GLM group:29patients, MDE group:77patients, GLM&MDE group:12patients) admitted to department of Breast Surgery in Qilu Hospital and treated by surgery from January2010to January2012were retrospectively analyzed. All the pathological slides were analyzed by a practiced pathologist, blinded to the diagnosis. The clinicopathologic features for GLM and MDE were compared.Results:The41patients(29GLM and12GLM combined with MDE) accounted for2.06%of all the operable inpatients (41/1992) and3.50%of the patients with breast benign disorder (41/1173), who admitted to Breast Surgery Department of Qilu hospital from a similar time period. Although parity was similar for all groups,22(88%) GLM patients had given birth in the last5years, compared with35(52.2%) MDE patients(x2=9.878, P=0.002). Mass size was significantly larger in GLM group than in MDE group(Z=-3.944, P<0.001). GLM group had a lower incidence of abscess (or with rupture of abscess)(x2=4.062, P=0.044), and a higher incidence of mastalgia(x2=7.256, P=0.007) and mass with pain(x2=14.24, P<0.001). Comparing the different histological features, GLM group showed significantly granulomatous inflammatory reaction centered on lobules(x2=71.44, P<0.001), and had higher incidence of microabscess formation within lobules(x2=59.44, P<0.001), granuloma(x2=25.11, P<0.001) and microabscess formation(x2=23.88, P<0.001) within the surrounding tissue. More multinucleated giant cells within granuloma were seen in GLM group(x2=22.68, P<0.001). There were significantly more neutrophilic granulocytes found within and around lobules(x2=24.99, P<0.001) in GLM group. MDE group showed significantly dilatation of duct terminals(x2=68.78, P<0.001) and inflammatory changes in the walls of ducts and periductal tissues(x2=66.77, P<0.001). Compared with GLM group, MDE group had higher incidence of foam cells within the duct epithelium and in the surrounding stroma(x=38.44, P<0.001), stasis material in the dilated duct(x2=69.73, P<0.001), periductal fibrosis(x2=79.69, P<0.001) and hyperplasia of duct epithelium(x2=44.71, P<0.001).Conclusions:GLM is a rare benign breast disorder with different clinicopathologic characteristics as compared with MDE. GLM was more likely to occur in patients given birth more recently with a larger clinical mass and more mastalgia. Recent pregnancy and breast feeding may be correlated with the onset of GLM. There were significant differences found between GLM and MDE group histologically. GLM showed significantly granulomatous inflammatory reaction centered on lobules. There were more microabscess formation within lobules, granuloma and microabscess formation within the surrounding tissue and multinucleated giant cells within granuloma in GLM. More neutrophilic granulocytes were found within and around lobules in GLM than in MDE. Currently complete surgical excision with negative margin is the main treatment modality to reduce the incidence of recurrence.