Pathology Thread

III. Inflammatory Conditions

Objectives:

After completing this section you will be able to:

• describe the physiologic hormone-induced changes in the breast, and
• relate the changes to various stages of the female reproductive cycle

1. Acute Mastitis and Breast Abscess

This is acute bacterial infection of the breast and may be seen at any age but typically occurs 2 to 3 weeks at start of lactation. It usually results from infection via the duct system, which may be blocked by inspissated secretions resulting in stasis. The most common organism is Staph. aureus. The infection may progress to abscess formation. A firm, walled-off, non-tender abscess may be clinically mistaken for breast cancer.

2. Fat necrosis

Fat necrosis occurs most frequently in women with pendulous breasts. The typical presentation is a painless mass located superficially in the breast, accompanied by retraction or dimpling of the skin due to fibrous scar tissue extending into the adjacent tissue. They are firm to hard, fixed and irregular by palpation. A history of trauma may be elicited.

Mammographic examination reveals a spiculated, often poorly defined mass lesion that may contain punctate or irregular calcifications. The lesion consists of yellow gray and focally red mass, which may contain foci of cystic degeneration filled with oily fluid or necrotic fat. Dystrophic calcification is a common feature.

Histologically, there is disruption of adipocytes and hemorrhage. This is followed by infiltration with histiocytes including multinucleated giant cells, variable number of lymphocytes and plasma cells, hemosiderin deposition, and marked fibrosis.


Fat necrosis showing types of inflammatory cells present and fibrosis.


Far necrosis. High power view showing mulinucleate giant cells.

The lesion is completely benign.

Question: What is the clinical importance of fat necrosis?

 

3. Mammary Duct Ectasia

Duct ectasia refers to the presence of dilated lactiferous and interlobular ducts of the breast accompanied by periductal inflammation and fibrosis. The etiology is not known. The condition is found in the elderly, in whom it occurs superficially in the lactiferous ducts immediately under the areola. It is infrequently found in younger women in a peripheral location involving the intermediate-sized interlobular ducts. This peripheral form may be clinically difficult to distinguish from cancer.

At surgery, obviously dilated ducts are easily identified. The mass usually consists of firm breast tissue in which there are prominent ducts containing pasty, inspissated secretions, which vary in color from white through cream to brown. Calcification is sometimes seen.

Microscopically, dilated ducts containing eosinophilic, amorphous or granular acellular debris usually admixed with lipid-laden histiocytes and desquamated duct epithelial cells are seen. Circumferential inflammatory changes with chronic inflammatory cells and foam cells are present throughout the thickness of the duct epithelium and periductal stroma. Rupture of the duct leads to discharge of contents accompanied by more intense periductal inflammation with foreign body granulomas. Cholesterol crystals and calcifications may be found in the intraductal debris. Squamous metaplasia of lactiferous ducts may be seen in some cases.

The condition is completely benign.

4. Granulomatous Mastitis

   Granulomatous mastitis is a descriptive term, which encompasses many specific lesions. However, the term has come to be associated with a distinct idiopathic clinicopathologic condition.

   The age range at diagnosis ranges from 17 to 42 years. Virtually all patients are parous with mean interval between last pregnancy and disease of 2 years. Patients present with a distinct firm-hard mass involving any part of the breast but tends to save the subareolar region. There is no nipple discharge and bilateral involvement is uncommon.

Injection of liquid silicone into breasts for cosmetic augmentation led to a diffuse foreign body granulomatous reaction throughout the breast. Silicone is now encased within a synthetic covering and implanted. However silicone slowly leaks into the surrounding breast tissue leading to the formation of a fibrous capsule with granulomatous reaction including foreign body giant cells.

Nodularity, skin retraction, hard masses and/or nipple inversion, all of which may simulate carcinoma, complicate silicone mastitis. Axillary node enlargement secondary to migration of silicone simulates metastatic carcinoma. Fine calcifications like those seen in carcinoma may be seen on mammography. There has been no report of carcinoma following injection of liquid silicone or leakage from implants.