Fitoplancton en los periodos oceanográficos

Differences between normal and abnormal breast tissue are often subtle, characterized by cellular features (typical versus atypical) and growth patterns (proliferative versus nonproliferative). Many of these features are important for

mammographic detection and appropriate characterization of lesions. Several benign and atypical conditions are shown in Tables 2.2 and 2.3, respectively. Nonproliferative benign conditions are growths of disregulated cells, typically only harmful if the location disrupts normal function, such as blockage of proper lymphatic drainage. Some

neoplasms do confer an increased risk for cancer development, usually classified as atypical or proliferative. (Jacobs 1999, Ikeda 2004, Hartmann 2005, Harris 1991)

Calcifications Features

Duct Ectasia Yes Wide, hard ducts sometimes forming a mass Oil Cyst Some Well-circumscribed round, oil-filled mass

Fat Necrosis Some Round, fatty mass (occasionally spiculated, cystic) Hamartoma Some Uncommon circumscribed, fatty/fibrotic mass Papillary Apocrine Change None Proliferation of ductal epithelial cells

Fibrocystic Disease Some Proliferative, palpable mass with multiple cysts, stromal fibrosis, apocrine metaplasia

Fibroadenoma Some Common well-circumscribed, solid mass Fibromatosis Rare Locally invasive mass of fibroblast proliferation Benign Vascular Lesions Some Hemangioma, angiolipoma

Granular Cell Tumor None Uncommon palpable, poorly circumscribed mass Lipoma Some Circumscribed, hard fatty mass

Papilloma Some Individual or multiple well-circumscribed ductal mass(es), often with intraductal hyperplasia, sclerosing adenosis

Phyllodes Tumor Rare Round, dense fibrotic mass Mastitis Yes Inflammation

TABLE 2.2: Benign Breast Conditions. Although this is not an exhaustive discussion of benign breast diseases, several common conditions are listed. Typical clinical and mammographic presentations are noted, including whether calcifications are usually associated with the condition. (Rosen 2001)

Common benign inflammatory and reactive diseases include duct ectasia and fat necrosis. Mammary duct ectasia is characterized by dilation of the ducts with

inflammatory changes within the ducts and surrounding tissues that sometimes becomes fibrotic or cystic. Fat necrosis typically results from an injury to the tissue from trauma, surgery or high radiation exposure. These masses are usually small and sometimes contain calcifications or cysts. (Rosen 2001)

Calcifications Features

Lobular Neoplasia (LCIS) None Proliferation of lobular cells (often with ALH) Atypical Ductal / Lobular Yes Proliferation of ductal or lobular epithelial cells Hyperplasia (ADH, ALH)

Radial Scar (RS) Yes Irregular, proliferative mass with atrophic center, often occurring in multiples or with cysts, DCIS, ADH, SA Sclerosing Adenosis (SA) Yes Proliferation of glandular and stromal cells into fibrotic mass TABLE 2.3: Atypical Breast Lesions. Some benign conditions are considered atypical and proliferative, and confer an increased risk of subsequent cancer development. These lesions are often considered to be precancerous or closely associated with the presence of cancer. (Rosen 2001)

Several benign tumors are closely associated with the presence of cancer or are considered precancerous lesions. Although papillomas are benign masses in the ductal epithelium, papillary carcinoma is often associated with areas of benign papillomas. Multiple papillomas tend to have greater precancerous potential. Phyllodes tumors arise from stroma surrounding the ducts to become benign, low-grade malignant, or high-grade malignant tumors, and are sometimes associated with LCIS or invasive ductal carcinoma. (Rosen 2001)

Neoplasia is a proliferative lesion with atypia and carries a risk of breast cancer development. Lobular carcinoma in situ (LCIS) is a non-malignant, high-risk lesion which is difficult to detect through mammographic screening due to its growth pattern

lumens instead of within them. Interestingly, LCIS is most often associated with invasive ductal carcinoma. Proliferative and atypical lesions are often associated with, or develop into, cancerous lesions. (Rosen 2001)

Ductal and lobular hyperplasias are proliferative lesions that are considered precancerous. Sclerosing lobular hyperplasia is often associated with a fibroadenoma. Radial scars are considered precancerous by some experts because they are proliferative in nature and are found more often in women with breast cancer than those without. LCIS lesions are often associated with radial scars. However, most radial scars are too small to be reliably detected by clinical exam or mammography. Sclerosing adenosis is a

proliferative lesion of the TDLU. Although fibroadenomas are generally benign tumors, they sometimes develop adenosis, which carries a risk of breast cancer development. Even though nonproliferative fibrocystic change does not convey increased breast cancer risk, the proliferative variant is composed of several disease processes that each conveys increased risk, such as ductal hyperplasia and sclerosing adenosis. (Rosen 2001)

Several common breast cancers are summarized in Table 2.4. Ductal carcinoma in situ (DCIS) is a non-malignant lesion originating in the TDLU. Although DCIS

sometimes develops metastatic potential, it typically has an excellent prognosis. Papillary, tubular, and mucinous carcinomas are additional cancers that are associated with good prognoses. Invasive ductal carcinomas represent 65-80% of malignant breast cancer diagnoses. Medullary carcinoma is a rapidly-growing receptor negative cancer more common among women with BRCA mutations, and is associated with a poor prognosis. (Rosen 2001)

Invasive Features

Ductal Carcinoma in Situ No Ductal mass often with necrosis, calcifications

Papillary Carcinoma Not Often Individual or multiple slow-growing, round ductal mass(es), sometimes with inflammation, fibrosis, cysts, hemorrhage Invasive Ductal Carcinoma Yes Irregular, spiculated ductal mass often with necrosis, hemorrhage Invasive Lobular Carcinoma Yes Single-cell lines of lobular cancer cells or irregular mass

Medullary Carcinoma Yes Circumscribed, rapidly-growing, poorly-differentiated mass Tubular Cancer Yes Slow-growing, irregular, spiculated mass, often with DCIS, RS Inflammatory Carcinoma Yes Mastitis, skin thicknening

Mucinous Carcinoma Yes Slow-growing, soft mass in mucinous picket, often with DCIS Adenoid Cystic Carcinoma Yes Rare, slow-growing mass with excessive mucin

Sarcoma Yes Well-circumscribed mass Lymphoma Yes Often well-circumscribed

TABLE 2.4: Malignancies of the Breast. Although this is not an exhaustive list, it summarizes some of the more common breast cancers. Common clinical and

mammographic presentations are listed, with indication of whether the lesion represents a lesion capable of invading surrounding tissue and metastasizing to distant sites within the body. (Rosen 2001)