33 Special Types of Invasive Breast Carcinoma: Diagnostic Criteria ...

invasive micropapillary carcinoma may be highly aggressive (8). In any event, it is
important that, whether cystic and/or solid, papillary carcinoma without invasion can
be considered a form of “intraductal” carcinoma (1,9,10), and patients with
noninvasive papillary carcinoma are essentially cured by mastectomy (1). But,
recurrences can occur with pre-invasive examples, and they can be either in situ
and/or invasive diseases.
Clinicopathologic features: Papillary carcinomas occur in an older age group (mean
ages from 63 to 67 years) than InvDC,NST (11). They tend to occur centrally, and
nipple discharge and/or bleeding develops in ~33% of patients (1,4). Invasive
papillary carcinomas can be large tumors, due to the bulky, cystic component
frequently present. The average size is 2 to 3 cm, and, as their often low histologic
grade would predict, papillary carcinomas are hormone receptor-positive in the
majority of cases (12,13). Papillary carcinomas are usually circumscribed, as are
fibroadenomas, benign cystic lesions, and medullary or mucinous carcinomas (14,15).
Invasion is suggested by an irregular contour (14). Cut surfaces are brown or
hemorrhagic, but usually they are tan or grey.
Although variable, the arborescent fronds of papillary carcinoma are usually
composed of very delicate fibrovascular cores; indeed, the fibrous component may be
inconspicuous. The lining epithelial cells are of a single type, showing high nuclear to
cytoplasmic ratios, increased mitotic activity, and usually uniform, hyperchromatic
nuclei. Furthermore, the tumor cells may show stratification and resemble
adenomatous polyps of the colon. Mitotic figures are variably present and more
numerous in lesions that exhibit the most severe cytologic atypia. Myoepithelial cells,
distributed relatively uniformly and proportionately within the epithelium in benign
papillary lesions, are largely overgrown in papillary carcinomas; but, they may not be
entirely absent from a papillary carcinoma. The finding of myoepithelial cells in some
parts of a papillary lesion is not inconsistent with a diagnosis of carcinoma (16-18).
“Intracystic papillary carcinomas” (IPC) is an uncommon breast tumor usually
developing in elderly patients (median age ~70, range 27 to 99); and, they present as
discrete, circumscribed solitary masses (usually subareolar), which are present within
ducts of at least 1 cm in diameter by definition (1,9). 3.5% occur in men (19). They
often contain dark brown, partly clotted blood and detached degenerated papillary
fragments of the tumor. Mural nodules of residual tumor can usually be found on the
inner or luminal surface or in the cyst wall. Presenting as a discrete cystic mass,
“intracystic papillary carcinoma” has been considered a special form of preinvasive or
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