[Granulomatous lobular mastitis: a clinicopathological analysis of 300 cases]

Objective: To investigate the clinicopathologic features and possible causes of granulomatous lobular mastitis(GLM). Methods: Three hundred cases of GLM were collected from surgical specimens diagnosed at Longhua Hospital, Shanghai University of Traditional Chinese Medicine from January 2015 to November 2017. Morphologic features were reviewed using HE staining. A total of 116 cases were investigated by Gram staining. The expression of CD3, CD20, CD68, IgG, IgG4, CD38 and CD138 was detected by immunohistochemical staining. Results: The age of the patients was 23 to 47 years and the median age was 32 years. All patients were female, 96.7% (290/300) had a history of lactation.There were 143 cases of left breasts, 138 cases of right breast and 19 cases of bilateral breasts. Serum prolactin increased in 39.7%(119/300) patients. Within 15.7%(47/300) of patients were associated with nodular erythema or joint swelling and pain of the lower extremities. Pathological observation showed that lobular-centric suppurative granulomatous inflammation, accompanied by dilatation of intralobular and interlobular ducts. There were 16 cases accompanied with duct ectasia. Immunohistochemistry showed CD3-positive lymphocytes were more than CD20-positive lymphocytes in the peripheral aggregation zone of neutrophils within granulomatous lesions. Gram positive bacteria were found in the lipid vacuoles of the 51.7%(60/116) patients. Conclusions: GLM has distinctive histologic features. It may be related to corynebacterium infection, or accompanied by the increase of serum prolactin and erythrocyte sedimentation rate. The age, location and history of the disease are importance in the diagnosis and differential diagnosis.