The Cytomorphological Spectrum of Papillary Lesions in the Breast

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The objective of this review is to illustrate the broad spectrum of papillary lesions that can be found in breast fine needle aspirations (FNAC). Papillary tumors of the breast comprise lesions of variable morphology and include entities ranging from benign to high grade malignant. Features of papillary neoplasms invariably describe branching three-dimensional papillary clusters with delicate fibrovascular cords. Cytomorphological criteria for benign and low-grade malignant entities overlap and a definite cytological diagnosis is not always possible. Cellular papillomas may harbor areas of ductal carcinoma in situ (DCIS), atypical ductal hyperplasia (ADH) or lobular neoplasia. DCIS can be both high grade and non-high grade. Immunocytochemistry (ICC) can be helpful, providing there is adequate material for ICC. Relatively high error rates, false negatives as well as false positive diagnoses can be found. In general, papillary lesions may be recognized as such. Reporting strategies will often recommend caution if trying to differentiate benign, cellular papillomas from low-grade carcinomas.

Papillary tumors of the breast comprise lesions of variable morphology and include entities ranging from benign to high grade malignant (table 1). A papillary neoplasm is histologically one that exhibits an arborescent epithelial proliferation with fibrovascular cores and is attached by a stalk to the wall of a dilated duct. They constitute < 2 % of all breast lesions.

Cytomorphological criteria for benign and low-grade malignant entities overlap and a definite cytological diagnosis is not always possible. Features of papillary neoplasms invariably describe branching three-dimensional papillary clusters with delicate fibrovascular cords. Additional features of papillary carcinomas include moderate to abundant cellular material small papillae arranged in cell balls, tall columnar cells, isolated naked nuclei and hemosiderin laden macrophages irregular groups of predominantly monolayered (two-dimensional) epithelium composed of small, polygonal or cuboidal cells with eosinophilic cytoplasm and rounded, eccentrically placed nuclei. Features indicating a benign papillary lesion include less cell material, papillae with cohesive stalks surrounded by columnar cells in a honeycomb pattern, apocrine metaplasia, bipolar naked nuclei as well as fewer small papillae and isolated columnar cells. Myoepithelial cells within clusters and inconspicuous naked, bipolar nuclei in the background also indicate a benign lesion.