Sclerosing adenosis refers to a proliferative breast lesion in which various elements have become hardened, damaged, or otherise distorted. Sclerosing adenosis is considered to be a benign lesion, but can sometimes confused with tubular carcinoma, particularly if some lobular neoplasia is evident. A sclerosing adenosis lesion may be completely asymptomatic, or may present as a palpable mass in a clinical exam.
'Adenosis' means 'increased in number', and 'sclerosis' means 'hardening'. Histologically,(examined after biopsy) sclerosing adenosis often presents as a proliferation of elongated, obliterated, or distorted glands and tubules, in addition to hardening of surrounding collagen and stroma tissue. The condition is sometimes called fibrosing adenosis, or adenofibrosis, and tends to arise from problems with the terminal duct lobular unit. (TDLU)
On a mammogram, sclerosing adenosis is rather variable in its presentation. It usually appears bilaterally, and often with diffuse and scattered microcalcifications. It can also present as an asymmetric density with microcalcifications, a solitary cluster of microcalcifications, or as a non-calcified mass. When these rarer, unusual presentations occur, it is best to have the findings verified with a biopsy. When it presents as a mass it is referred to as either 'nodular adenosis' or 'adenosis tumor', but it is not a tumor and is not cancerous.
Sclerosing adenosis occurs most frequently with women between the ages of 30 and 45. It is quite common, accounting for about 12% of breast biopsy specimens. The development of sclerosing adenosis has no direct link to breast carcinoma. It is not 'pre-cancerous'. However, as is the case with many common benign breast abnormalities, malignant lesions can sometimes develop within them.
Over the long term, it is thought that sclerosing adenosis increases the risk of subsequent breast cancer development approximately two times. But to clarify, this does not mean that the sclerosing lesion brings about increased risk. What it means, is that the same genetic predispositions which have brought about the sclerosing adenosis, will also give a woman an increased predisposition towards possible breast carcinoma development.
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