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

tumors is not surprising.
Infiltrating syringomatous adenoma is closely related to tumors described in other
locations such as microcystic adnexal carcinoma, sclerosing sweat duct
(syringomatous) carcinoma, and syringomatous tumor of minor salivary gland (29-
31). Although locally recurrent in 50% of cases, infiltrating syringomatous adenoma
should be recognized as a "benign," yet locally aggressive tumor. When infiltrating
syringomatous adenoma occurs outside the nipple and within the breast parenchyma,
it has been described as low-grade adenosquamous carcinoma (32). Infiltrating
syringomatous adenoma presents as a firm mass in the nipple or subareolar region (1-3
cm diameter). The patient population covers a wide age group, from 11 to 76 years.
(mean about 40 years). This neoplasm is composed of small ducts two cell layers
thick, solid epithelial strands, and small keratin cysts that extent into smooth muscle,
dermis, perineural spaces, and underlying breast parenchyma. Local excision with
clear margins is the preferred curative therapy; although recurrences have occurred in
up to 50% of cases. The term “infiltrating syringomatous adenoma” is preferred over
“carcinoma,” to avoid excessive surgery and patient anxiety. Yet, adequate treatment
may require nipple resection (29-31). But, please know that Foschini et al. (41)
reported six cases of invasive breast carcinoma with unusual morphological features.
The ages of the female patients ranged from 46 to 79 years (mean 60.5). All tumours
had areas typical of an adenomyoepithelioma. In three cases adenomyoepithelioma
gradually merged with low-grade adenosquamous carcinoma. In the other three
patients a sarcomatoid carcinoma was associated with adenomyoepithelial areas. A
common origin was proposed for these neoplasms, which extends the morphological
spectrum of adenomyoepithelial cell tumours.
Salivary gland-type neoplasms of the breast are uncommon and comprise numerous
entities analogous to that more commonly seen in salivary glands. The
clinicopathologic spectrum ranges from benign to malignant but there are important
differences as compared with those of their salivary counterpart. In the breast, benign
adenomyoepithelioma is recognized in addition to malignant one, whereas in the
salivary gland a histologically similar tumor is designated as epithelial-myoepithelial
carcinoma without a separate benign subgroup. Mammary adenoid cystic carcinoma is
a low-grade neoplasm compared with its salivary equivalent. It is also important to
appreciate that in contrast to "triple negative" conventional breast carcinomas with
aggressive course, most salivary-type malignant breast neoplasms behave in a lowgrade
manner. Most of these tumors are capable of differentiating along both epithelial
and myoepithelial lines, but the amount of each lineage-component varies from case to
case, contributing to diagnostic difficulties. Well established examples of this group
include pleomorphic adenoma, adenomyoepithelioma, and adenoid cystic carcinoma.
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