CARCINOMAS OF THE BREAST WITH ENDOCRINE DIFFERENTIATION - A REVIEW

The occurrence of endocrine differentiation in some mammary carcinomas seems well-established, but pathologists continue to debate its signi ficance. Contemporary thinking suggests that endocrine tumours of the breast do not constitute a single clinicopathological entity with a co nsistent histogenesis but rather that ens docrine differentiation repr esents a pathway of neoplastic development available to a range of bre ast cancers. This pattern of differentiation occurs in tumours with va stly different morphological appearances, such as: ductal carcinoma in situ, mucinous carcinoma, a variant of lobular carcinoma, and low gra de invasive ductal carcinoma. Although such tumours share some charact eristics with intestinal endocrine neoplasms, the typical pattern of i ntestinal carcinoid virtually never occurs in mammary lesions. Convent ional microscopy permits the diagnosis in most cases. Specialized tech niques (histochemistry, immunohistochemistry, and electron microscopy) can serve as the basis for diagnosis in the absence of the appropriat e morphological features. Although the system of nomenclature proposed by the World Health Organization for use with endocrine tumours in ot her organs can be used for endocrine tumours of the breast, only a min ority of lesions will fit the established criteria. Most lesions are c lassifiable in the conventional categories of mammary carcinomas. No s pecial prognostic significance is attached to these tumours at the pre sent time.