Atypical ductal hyperplasia

Atypical ductal hyperplasia
Very low magnification micrograph of atypical ductal hyperplasia (ADH). The piece with ADH was circled by the pathologist with a marker, as it is so small, and sent for an additional opinion. H&E stain.
Classification and external resources
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Atypical ductal hyperplasia, abbreviated ADH, is the term used for a benign lesion of the breast that indicates an increased risk of breast cancer.

The name of the entity is descriptive of the lesion; ADH is characterized by cellular proliferation (hyperplasia) within one or two breast ducts and (histomorphologic) architectural abnormalities, i.e. the cells are arranged in an abnormal or atypical way.

In the context of a core (needle) biopsy, ADH is considered an indication for a breast lumpectomy, also known as a surgical (excisional) biopsy, to exclude the presence of breast cancer.

ADH, generally, is asymptomatic. It usually comes to medical attention on a screening mammogram, as a non-specific suspicious abnormality that requires a biopsy.

It is diagnosed based on tissue, e.g. a biopsy. Histomorphologically, it has architectural changes seen in low-grade ductal carcinoma in situ (DCIS), e.g. cribriform architecture, and like low-grade DCIS has minimal nuclear atypia and no necrosis.

ADH, cytologically, architecturally and on a molecular basis, is identical to a low-grade ductal carcinoma in situ (DCIS); however, it has a limited extent, i.e. is present in a very small amount (< 2 mm).

While the histopathologic features and molecular features of ADH are that of (low-grade) DCIS, its clinical behaviour, unlike low-grade DCIS, is substantially better; thus, the more aggressive treatment for DCIS is not justified. In oncology in general, it is observed that tumour size is often strongly predictive of the clinical behaviour and, thus, a number of cancers (e.g. adenocarcinoma of the lung, papillary renal cell carcinoma) are defined, in part, on the basis of a minimum size.

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