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 ?
Microglandular adenosis is a mimic of tubular carcinoma.
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.
Of note, microglandular adenosis is considered to be a neoplastic precursor lesion.
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.
Carcinomas with osseous or chondroid differentiation, carcinosarcomas, and carcinomas arising from microglandular adenosis are developmentally complex lesions that require substantially more assessment at the molecular level for a better understanding of their evolution and identification of potential targets for therapy.
There are several types of adenoses that may resemble invasion both radiologically and histologically, such as sclerosing adenosis, tubular adenosis, and 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.