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Pathology - Proliferative breast diseases
Definition: A heterogeneous collection of intraductal proliferative lesions of the breast linked to a variable risk for the later emergence of invasive breast cancer. Epidemiology • Extremely prevalent. • Incidence has increased following the implementation of breast screening programs.
Aetiology • Comparable to invasive breast carcinoma (see p. 226). Genetics • The majority of instances of flat epithelial atypia and in situ lobular neoplasia exhibit genetic anomalies, particularly the loss of heterozygosity on chromosome 16p. A fraction of typical epithelial hyperplasia instances exhibit genetic abnormalities.
Macroscopy: The majority are detected through screening mammography or accidentally during the excision of breast tissue for other purposes. Histopathology • Usual epithelial hyperplasia is characterized by a disorganized proliferation of juvenile ductal epithelial cells that create slit-like spaces. • Flat epithelial atypia involves a consistent proliferation of moderately atypical ductal epithelial cells, not exceeding five cells in thickness. This is considered the earliest morphological precursor of low-grade ductal carcinoma in situ. In situ lobular neoplasia is characterized by a proliferation of tiny, weakly cohesive epithelial cells, marked by the loss of E-cadherin expression as determined immunohistochemically.
Prognosis • Typical epithelial hyperplasia is not regarded as a direct precursor lesion for invasive breast carcinoma; however, it serves as an indicator of a modestly elevated risk (relative risk of 1.5–2.0) for subsequent invasive carcinoma. • Currently, there is no quantitative data regarding the relative risk for the future development of invasive breast carcinoma in patients with flat epithelial atypia.
Recent genetic findings indicate that flat epithelial atypia may serve as the initial morphological precursor to low-grade ductal carcinoma in situ. Current research indicates that in situ lobular neoplasia poses a risk for eventual invasive breast carcinoma in either breast in a minority of women. The relative risk is reported to be between 7 and 12 times greater than that anticipated in women devoid of lobular neoplasia.
Definition: A heterogeneous collection of intraductal proliferative lesions of the breast linked to a variable risk for the later emergence of invasive breast cancer. Epidemiology • Extremely prevalent. • Incidence has increased following the implementation of breast screening programs.
Aetiology • Comparable to invasive breast carcinoma (see p. 226). Genetics • The majority of instances of flat epithelial atypia and in situ lobular neoplasia exhibit genetic anomalies, particularly the loss of heterozygosity on chromosome 16p. A fraction of typical epithelial hyperplasia instances exhibit genetic abnormalities.
Macroscopy: The majority are detected through screening mammography or accidentally during the excision of breast tissue for other purposes. Histopathology • Usual epithelial hyperplasia is characterized by a disorganized proliferation of juvenile ductal epithelial cells that create slit-like spaces. • Flat epithelial atypia involves a consistent proliferation of moderately atypical ductal epithelial cells, not exceeding five cells in thickness. This is considered the earliest morphological precursor of low-grade ductal carcinoma in situ. In situ lobular neoplasia is characterized by a proliferation of tiny, weakly cohesive epithelial cells, marked by the loss of E-cadherin expression as determined immunohistochemically.
Prognosis • Typical epithelial hyperplasia is not regarded as a direct precursor lesion for invasive breast carcinoma; however, it serves as an indicator of a modestly elevated risk (relative risk of 1.5–2.0) for subsequent invasive carcinoma. • Currently, there is no quantitative data regarding the relative risk for the future development of invasive breast carcinoma in patients with flat epithelial atypia.
Recent genetic findings indicate that flat epithelial atypia may serve as the initial morphological precursor to low-grade ductal carcinoma in situ. Current research indicates that in situ lobular neoplasia poses a risk for eventual invasive breast carcinoma in either breast in a minority of women. The relative risk is reported to be between 7 and 12 times greater than that anticipated in women devoid of lobular neoplasia.
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