Clinicopathological features of granulomatous lobular mastitis and mammary duct ectasia

Granulomatous lobular mastitis (GLM) and mammary duct ectasia (MDE) are inflammatory diseases. However, only a limited number of studies have focused on characterizing their clinicopathological features. The aim of the present study was to investigate the etiology, clinicopathological characteristics and diagnosis of GLM and MDE. The clinical information and treatment of 118 female patients with pathologically-proven GLM or MDE were retrospectively analyzed in the present study. A total of 29 cases had GLM, 77 had MDE and 12 had GLM accompanied by MDE. GLM tends to occur in patients who have had their last birth within 5 years and are usually <40 years of age. GLM masses were usually larger than MDE masses and suppurated or ulcerated more easily. Histopathologically, GLM was characterized by a significant granulomatous inflammatory reaction centered on lobules. Compared with MDE, GLM had a higher incidence of granuloma and microabscess formation within the lobules and surrounding tissue. More multinucleated giant cells within granuloma were observed in patients with GLM than in those with MDE, while MDE was characterized by significant dilatation of the duct terminals and inflammatory changes in the duct wall and periductal tissues. When compared with patients with GLM, foam cells within the duct epithelium or surrounding stroma were more common in patients with MDE. The present study demonstrated that GLM and MDE had distinct clinicopathological characteristics. Further research is required in order to identify more appropriate treatment strategies for these specific types of breast inflammation.