microglandular adenosis

mi·cro·glan·du·lar ad·e·no·sis

adenosis of the breast in which irregular clusters of small tubules are present in adipose or fibrous tissues, resembling tubular carcinoma but lacking stromal fibroblastic proliferation.

microglandular adenosis

A haphazard proliferation of uniform, cytologically bland glands in the breast which presents as a poorly cicumscribed mass. Up to 27% of cases have in situ or invasive cancer at the time of diagnosis; it may evolve to breast carcinoma.
 
DiffDx
Acinic cell carcinoma (breast).

mi·cro·glan·du·lar ad·e·no·sis

(mī'krō-glan'dyū-lăr ad'ĕ-nō'sis)
Glandular disease of the breast in which irregular clusters of small tubules are present in adipose or fibrous tissues, resembling tubular carcinoma but lacking stromal fibroblastic proliferation.
References in periodicals archive ?
Benign lesions without MEP cells (Table 4) include microglandular adenosis, which is an infiltrative, benign breast lesion consisting of small, round, open glands formed by a single layer of flat to cuboidal epithelial cells with fibrous or fatty stroma.
An association with microglandular adenosis has also been reported.
Summary of histopathologic diagnosis Histopathologic diagnosis Histopathology coding High grade Low grade Total lesion lesion number of cases Adenocarcinoma 2 0 2 Atrophy 0 2 2 Chronic cervicitis (CC) 0 42 42 Cervical intraepithelial 0 2 2 neoplasia (CIN 1) Cervical intraepithelial 3 0 3 neoplasia (CIN 3) Condyloma 0 7 7 Dysplastic glands can't r/o 1 0 1 adenocarcinoma Endocervlcal polyp (ECP) 0 6 6 Granulation tissue 0 1 1 Microglandular adenosis 0 4 4 Radiation changes 0 6 6 Squamous metaplasia 0 26 26 Suspicious for malignancy 1 0 1 Total 7 96 103 Table 2.
Neoplastic lesions with intraluminal secretions include microglandular adenosis, secretory carcinoma, cystic hypersecretory carcinoma, and invasive ductal carcinoma, not otherwise specified (with intraluminal secretions).
Microglandular adenosis, with its permeative pattern of small glands and absence of myoepithelial cells, is a major diagnostic hazard, especially on limited core biopsy samples.
(39,41) Other variants of TNBC include medullary carcinoma, apocrine carcinoma, adenoid cystic carcinoma, carcinomas arising in microglandular adenosis, myoepithelial carcinomas, and the spectrum of metaplastic carcinomas.
These lesions usually come into attention when they harbor calcifications detected by screening mammography, or if multiple affected lobules fuse together forming a mass, "adenosis tumor or nodular adenosis." There are several types of adenoses that may resemble invasion both radiologically and histologically, such as sclerosing adenosis, tubular adenosis, and microglandular adenosis. Rarely, foci of perineural invasion can be present in sclerosing adenosis.
(26) The rarest adenosis variant of AME has an infiltrative growth pattern that resembles microglandular adenosis. Microglandular adenosis is characterized by an absence of myoepithelial layer and S100 positivity.
(49) Nonetheless, in addition to its traditional uses (to establish nerve sheath differentiation, for example), S100 expression may be supportive of a diagnosis such as microglandular adenosis (MA) and its associated proliferations.
Microglandular adenosis is a notable example of a benign lesion with complete absence of an ME cell layer; in this setting, the basement membrane is actually multilayered and thickened, possibly to compensate for the loss of the ME cell layer.