Breast Pathology 24

Table 24-1. Anatomic Correlation to Common Breast Lesions

Normal	Lesion
Terminal duct	Cyst
Lobular unit	Sclerosing adenosis
	Small duct papilloma
	Hyperplasia
	Atypical hyperplasia
	Carcinoma
Lobular stroma	Fibroadenoma
	Phyllodes tumor
Nipple and areola:
Large ducts and lactiferous sinuses	Duct ectasia
	Recurrent subareolar abscess
	Solitary ductal papilloma
	Paget disease
Interlobular stroma	Fat necrosis
	Lipoma
	Fibrous tumor
	PASH*
*PASH = pseudoangiomatous stromal hyperplasia	Fibromatosis
	Sarcoma

MASTITIS

1.Acutemastitis is anacuteinflammation ofthebreast,commonlyoccurring during lactation. The most common infecting organism is Staphylococcus aureus.

2.Fatnecrosis is oftenrelatedto trauma or prior surgery, and it mayproduce a palpable mass or a lesion visible on mammography.

Note

MostCommon Causes ofBreastLumps

•Fibrocystic changes

•Normal breast, no disease

•Cancer

FIBROCYSTIC CHANGES

1.Fibrocystic changes (formerly called fibrocystic disease) are a collection of benign breast tissue changes with nonproliferative and proliferative components which increase the risk of breast cancer. Fibrocystic changes are extremely common and affect primarily women age 20 to 50 years. The changes most often involve the upper outer quadrant and may produce a palpable mass or nodularity.

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USMLE Step 1 • Pathology

Table 24-2. Nonproliferative Versus Proliferative Fibrocystic Changes

Nonproliferative	Proliferative Changes
Fibrosis	Ductal hyperplasia ± atypia
Cysts (blue-domed)	Sclerosing adenosis
Apocrine metaplasia	Small duct papillomas
Microcalcifications

Table 24-3. Relative RiskofDeveloping Breast Cancer with Fibrocystic Change

Relative Risk	Fibrocystic Change
No increase	Fibrosis, cysts, apocrine metaplasia, adenosis
1.5-2X	Sclerosing adenosis, ductal hyperplasia, papillomas
4-SX	Atypical ductal or lobular hyperplasia

Table 24-4. FeaturesThat Distinguish Fibrocystic Change from Breast Cancer

Fibrocystic Change	Breast Cancer
Often bilateral	Often unilateral
May have multiple nodules	Usually single
Menstrual variation	No menstrual variation
Cyclic pain and engorgement	No cyclic pain or engorgement
May regress during pregnancy	Does not regress during pregnancy

BENIGN NEOPLASMS

1. Fibroadenoma is the most common benign breast tumor in women <35 years of age; causes a palpable, round, movable, rubbery mass that on cross-section shows small, cleft-like spaces. Microscopically, the mass shows proliferation ofbenign stroma, ducts, and lobules.

2. Phyllodes twnor (cystosarcoma phyllodes) is a fibroadenoma variant that usually involves an older patient population (50s) and may locally recur or rarely metastasize. Microscopically, the mass shows increased cellularity, stromal overgrowth, and irregular margins.

3. Intraductal papilloma commonly presents as a bloody nipple discharge. Microscopically, papilloma causes benign papillary growth within lactifer­ ous ducts or sinuses.

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2. Histologicvariants

Chapter 24 • Breast Pathology

MALIGNANT NEOPLASMS

1. Carcinoma ofthe breast

a. Epidemiology. Carcinoma of the breast is the most common cancer in females, and affects 1 in 9 women in the UnitedStates. It is also the second most common cause ofcancer death. The incidence is increasing, and is higher in the United Statesthan in Japan.

b. Manyrisk factors have been identified.

i. The incidence increases with age; if there are first-degree relatives with breast cancer and if the patient has had prior breast cancer. It also increases if there has been unusually long/intense exposure to estrogens (long length ofreproductive life, nulliparity, obesity, exog­ enous estrogens) or if proliferative fibrocystic changes, especially atypical hyperplasia, are present.

ii. Hereditaryinfluences are thought to be involved in 5-10% ofbreast cancers,with important genes including BRCAI (error-free repair of DNA double strandbreaks) chromosome 17q21, BRCA2 (error-free repair of DNA double strand breaks) chromosome 13ql2-13, and P53 germ-linemutation (Li-Fraumeni syndrome).

c. Clinically, breast cancer can cause mammographic calcifications or architectural distortion; palpable solitarypainless mass; nipple retraction or skin dimpling; and fixation of breast tissue to the chest wall. Breast cancer is most common in the upper outer quadrant. Gross examination

ofa breast cancer typically shows a stellate, white-tan, gritty mass.

,

a.Preinvasive lesions include ductal carcinoma in situ (DCIS) carcinoma in situ (LCIS), and Paget disease of the nipple (see Other Breast Conditions below).

b.Invasive (infiltrating) ductal carcinoma is the most common form (>80%), and microscopicallyshows tumor cells forming ducts within a desmoplastic stroma.

c.Invasive (infiltrating) lobular carcinoma is present in around 5-10% ofcases; this form ofcarcinoma is characterized by small, bland tumor cells forming a single-file pattern. Invasive lobular carcinoma has a high incidence ofmultifocal and bilateral disease.

d.Mucinous (colloid) carcinoma is a form ofbreast carcinoma with better prognosis thatis characterized microscopicallybyclusters ofbland tumor cells floatingwithin pools ofmucin.

e.Tubular carcinoma rarelymetastasizes and has an excellent prognosis.

f.Medullary carcinoma is a form of breast carcinoma with a better prognosis; it is characterized microscopically by pleomorphic tumor cells forming syncytial groups surrounded by a dense lymphocytic host response.

g.Inflammatory carcinoma is related to tumor invasion into the dermal lymphatics with resulting lymphatic edema; it presents clinically with

red, warm, edematous skin. The term peau d'orange is used when the thickened skin resembles an orange peel. lobular

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Chapter 24 • Breast Pathology

© Giovannini, D'Atri, etal, World Journal ofSurgical Oncology2006. Used with permission.

Figure 24-2. Paget cells (arrows)

Chapter Summary

•Acute mastitis commonly occurs during lactation and is usually due to

Staphylococcus aureus.

•Fibrocystic change is an extremely common condition ofwomen 20 to 50 years ofage that can produce fibrosis, cyst formation, apocrine metaplasia, microcalcifications, ductal hyperplasia with orwithout atypia, sclerosing adenosis, and small duct papillomas.

•Fibroadenoma is the most common benign breast tumor ofwomen youngerthan

35 years of age, and produces a palpable, rubbery, movable mass.

•Cystosarcoma phyllodes is a large tumor involving both stroma and glands that behaves malignantly in 10-20% of cases.

•Carcinoma ofthe breast is the most common cancer in women, with a 1 in 9 incidence in the United States. Clinical features can include calcifications or architectural distortion visible by mammography, solitary painless mass, nipple retraction or skin dimpling, and fixation to the chest wall. Preinvasive lesions that may progress to breast cancer include ductal carcinoma in situ and lobular carcinoma in situ. Invasive cancer occurs in several histologic variants, including ductal carcinoma, lobular carcinoma, mucinous carcinoma, tubular carcinoma, medullary carcinoma, and inflammatory carcinoma.

•Paget disease ofthe nipple is an intraepidermal spread oftumorcellsthat is

commonly associated with an underlying invasive orin situ ductal carcinoma.

•Gynecomastia is a benign breast enlargement in a male, usually resulting from an increased estrogen to androgen ratio.

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