Periductal mastitis refers to the inflammatory process occurring around dilated ducts. The etiology and pathogenesis of periductal mastitis is debatable. One theory suggests that the process consists of initial duct dilatation followed by distention. This results in damage to the duct wall, thereby causing extravasation of lipid material, resulting in an inflammatory reaction. The alternative hypothesis suggests that duct ectasia may be the consequence of an initial periductal inflammatory process, with duct dilatation being a secondary event.

Colonization by bacteria may also play a part in the pathogenesis of this condition. Current evidence suggests that smoking is an important contributory factor in the etiology of this condition as it includes damage to the subareolar ducts.

Clinical Features
Pain associated with nipple discharge is a common presenting feature.

The pain is usually subareolar, noncyclical and associated with discharge from multiple ducts. There may be associated nipple retraction and an underlying subareolar mass. Patients may give a history of a previous breast abscess. An associated mammary-duct fistula with associated periareolar inflammation may often be noted.

Radiology
Ultrasound may reveal a thick-walled duct with an ill-defined margin due to the presence of inflammation. These appearances are nonspecific, and as a result, imaging has little or no diagnostic role other than excluding malignancy. The long-term sequelae of periductal mastitis may result in calcification that appears as areas of linear, frequently bilateral, crisplydefined calcification.

Pathology
Macroscopic Appearance
There are no specific appearances described in these cases.

Microscopic Appearance
Inflammation appears within and around the involved ducts. It may extend into adjacent breast lobules. Macrophages are almost invariably present.

Intense plasma-cell infiltrates (with or without associated noncaseating granulomatous inflammation) are also described.

In these latter cases, the presence of specific pathogens such as mycobacterium tuberculosis need to be considered and, if necessary, excluded.

Management
Initial management is with appropriate antibiotics until the inflammation settles. If there is a history of recurrent episodes of inflammation associated with nipple discharge, treatment should be by total duct excision and eversion of the nipple under antibiotic cover.

A.D. Purushotham, P. Britton and L. Bobrow
A prospective study of benign breast disease and the risk of breast cancer. JAMA 2002

References