Education And Debate

ABC of Breast Diseases: CARCINOMA IN SITU AND PATIENTS AT HIGH RISK OF BREAST CANCER

BMJ 1995; 310 doi: https://doi.org/10.1136/bmj.310.6971.39 (Published 07 January 1995) Cite this as: BMJ 1995;310:39
  1. D L Page,
  2. C M Steel,
  3. J M Dixon

    Carcinoma in situ

    Ductal carcinoma in situ: (left) comedo type carcinoma with extensive necrosis adjacent to viable malignant cells enclosed by basement membrane; (above) with central visible microcalcification.

    Lobular carcinoma in situ.

    Two main types of non-invasive (in situ) cancer can be recognised from the histological pattern of disease and cell type. Ductal carcinoma in situ is the most common form of non-invasive carcinoma (making up 3–4% of symptomatic and 17% of screen detected cancers) and is characterised by ducts and ductules expanded by large irregular cells with large irregular nuclei. In contrast, lobular carcinoma in situ is rare (0.5% of symptomatic and 1% of screen detected cancers) and presents as an expansion of the whole lobule by smaller regular cells with regular, round or oval nuclei.

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    Classification of ductal carcinoma in situ

    There has been a lack of agreement among pathologists about whether small lesions should be considered as hyperplasia or in situ carcinoma. In general, lesions that involve only a few membrane bound spaces and that measure less than 2–3 mm in their greatest diameter should be regarded as hyperplastic lesions (with or without atypia) and not in situ carcinoma. There is better agreement about larger lesions.

    Ductal carcinoma in situ

    Different classifications of ductal carcinoma in situ have been described, and these correlate to some degree with mammographic patterns of microcalcification.

    Presentation—Patients with symptomatic ductal carcinoma in situ present with a breast mass, nipple discharge, or Paget's disease. Screen detected carcinoma is most commonly associated with microcalcification, which may be localised or widespread and is characteristically branching and of variable size and density.

    Mammograms showing microcalcification characteristic of ductal carcinoma in situ: localised (left) and widespread (right).

    Natural course—Several studies have assessed the risk of subsequent invasive carcinoma in patients in whom ductal carcinoma in situ was missed by the pathologist …

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