Breast nonmalignant
Microglandular adenosis of breast

Topic Completed: 1 December 2014

Minor changes: 22 May 2020

Copyright: 2002-2019,, Inc.

PubMed Search: Microglandular adenosis [title] breast

Jaya Ruth Asirvatham, M.B.B.S.
Julie M. Jorns, M.D.
Page views in 2019: 9,344
Page views in 2020 to date: 4,138
Cite this page: Asirvatham JR, Jorns JM. Microglandular adenosis of breast. website. Accessed May 30th, 2020.
Definition / general
  • Rare lesion of haphazardly infiltrating, small, uniform, rounded, open glands with eosinophilic secretions
  • Mimics invasive carcinoma due to irregularly distributed glands in fibrous or adipose tissue, lined by single layer of cells
  • Also called microglandular hyperplasia
Clinical features
Radiology description
  • Increased density or calcifications
Case reports
Gross description
  • Palpable mass or small localized lesion
  • Infiltrative and ill defined
  • Usually 3 - 4 cm
Microscopic (histologic) description
  • Haphazardly infiltrating collection of small, uniform, rounded, open glands with eosinophilic secretions, irregularly distributed in fibrous or adipose tissue
  • Glands lined by single layer of cuboidal / flat cells with vacuolated / granular cytoplasm and bland nuclei
  • No apocrine snouts, no nucleoli, no / variable myoepithelial layer but thick basement membrane
  • Atypical microglandular adenosis:
    • Pleomorphic glands and microacini
    • Budding glandular units and luminal bridging, mild cytologic atypia, prominent nucleoli, reduced intraluminal secretions, occasional mitotic figures
    • Intact basement membrane
Microscopic (histologic) images

AFIP images

Multilayered epithelium with granular cytoplasm

Small round infiltrative glands

 Contributed by Dr. Mark R. Wick

H&E and reticulin stain

Images hosted on other servers:

Haphazard glands apparently infiltrating stroma

Ducts lined by single cells with secretory material

Smooth round glands

Small uniform glands with open lumina

With ALH

With invasive and intraductal carcinoma

Fig 2: Atypical microglandular adenosis

Cytology description
  • Sparse cellularity, monotonous population of medium sized cells with vacuolated clear cytoplasm, round and uniform nuclei, small nucleoli
  • Also clear cells that are solitary or clustered with spindly fibroblasts (Diagn Cytopathol 1993;9:72)
Positive stains
Negative stains
Electron microscopy description
Molecular / cytogenetics description
  • Clonal in some cases
Differential diagnosis
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