Solid Variant of Mammary Adenoid Cystic Carcinoma With Basaloid Features

Abstract

Adenoid cystic carcinoma of the breast is a rare neoplasm that represents <1% of breast carcinomas. The tumors are histologically indistinguishable from examples in other sites, and they have a generally favorable prognosis. Several studies have investigated the possible correlation between histologic grade in adenoid cystic carcinoma (largely determined by cytology and growth pattern) and prognosis. Some earlier reports concluded that a solid variant of mammary adenoid cystic carcinoma had a more aggressive clinical course, but others did not confirm this impression. This report describes nine patients with a solid variant of mammary adenoid cystic carcinoma that has a striking basaloid appearance. All were women ranging in age from 37 to 83 years. A solitary mass was evident in all patients. Tumor size was 1.1-15 cm (mean 3.7 cm). The tumors exhibited a predominantly solid architecture comprised of basaloid appearing cells with moderate to marked nuclear atypia. Five tumors had >5 mitotic figures per 10 high power microscopic fields. Intercalated ducts were found in all tumors, being well formed in six and poorly formed in three. Immunohistochemical stains for cytokeratins, basement membranes, and vimentin were consistently positive. Surgery was performed in all cases consisting of excision in seven and mastectomy in two. Axillary lymph node metastases were found in two of six axillary dissections and four had negative lymph nodes. The lymph nodes were not examined in three patients. Follow-up information was available for seven patients. Six women had no evidence of disease after follow-up of 2-88 months (mean 32 months), one patient died of unknown causes, and one patient was lost to follow-up. It is concluded that the solid variant of mammary carcinoma with basaloid features is a histologically distinct tumor that is capable of axillary metastases. Long-term follow-up of a larger series of cases will be needed to determine whether the prognosis of these patients differs significantly from that of women with conventional adenoid cystic carcinoma. Presently, these patients are candidates for axillary staging by sentinel lymph node mapping or low axillary dissection if there is no clinical evidence of axillary metastases. Systemic adjuvant treatment would be prudent when axillary nodal metastases are present. Breast-conserving surgery with radiation is an option if negative margins can be achieved because this appears to be a unicentric form of carcinoma.

KIT is highly expressed in adenoid cystic carcinoma of the breast, a basal-like carcinoma associated with a favorable outcome

“…By classifying breast cell populations according to the system proposed by Bocker, 36 we identified four distinct types of cells in adenoid cystic carcinoma of the breast; rare CK5/6 þ cells (CK8/18À/p63À) or progenitor cells, CK5/6 þ /CK8/18 þ cells (/p63À) or glandular precursor cells, CK8/18 þ cells Although the origin of adenoid cystic carcinoma of the breast is still debated, it seems to be widely accepted that this tumor is derived from undifferentiated cells, which have the capacity to differentiate towards ductal and myoepithelial cells. 9,10,25,37 Our study confirmed this theory, as we demonstrated the presence of CK5/6 þ cells that could represent precursor cells. However, even by using a double immunostaining procedure, we were unable to identify a CK5/6 þ /P63 þ population of cells which could correspond to myoepithelial precursor cells.…”

Immunoreactivity for c-kit and p63 as an adjunct in the diagnosis of adenoid cystic carcinoma of the breast

“…[1][2][3] The constituent neoplastic cells are both of luminal and myoepithelial type, arranged in a wide spectrum of histological patterns, that is, trabecular, tubular-cribriform, solid, and basaloid, which usually coexist in the same tumor. [1][2][3][4][5][6][7] Most adenoid cystic carcinomas follow a favorable clinical course with a low prevalence of axillary lymph node metastases (approximately 10%). Tumors showing a predominant solid pattern of growth however reportedly have a more aggressive behavior, 8 with distant metastases despite the absence of lymph node involvement and poor 5-year overall survival.…”

“…Tumors showing a predominant solid pattern of growth however reportedly have a more aggressive behavior, 8 with distant metastases despite the absence of lymph node involvement and poor 5-year overall survival. 6,[9][10][11][12][13] Adenoid cystic carcinoma, especially when showing a predominant tubular-cribriform growth pattern, shares many histological features with infiltrating cribriform and tubular carcinoma. These are more commonly encountered special types of breast cancer, characterized by a long-term survival in more than 80% of the cases.…”

“…Estrogen and/or progesterone receptors immunoreactivity, however, may also be detected in a minor subset of adenoid cystic carcinomas. 6,9,15,16 More specific and positive markers of adenoid cystic carcinoma would therefore be of diagnostic value.…”

Primary Adenoid Cystic Carcinoma of the Peripheral Lungs

“…ACC developing in the salivary glands is reported to exhibit a better prognosis than other pathological types of carcinoma occurring in the salivary glands, due to its slow growth and absence of metastasis until the late stages of tumor development [8]. Shin et al [9] reported that breast ACCs follow a favorable clinical course, with a better prognosis than that of salivary disease, while Cerar et al reported that esophageal ACCs have a worse prognosis due to their vital location and the development of synchronous tumors of the esophagus [10]. ACC has a distinctive microscopic appearance, and its histological features are useful not only in diagnosing the tumor but also help to determine the prognosis.…”