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    • Surgical Pathology Criteria
    http://surgpathcriteria.stanford.edu/

    Microglandular Adenosis of the Breast

    Definition

    • A haphazard proliferation of uniform, cytologically bland glands

    Diagnostic Criteria

    • Small, uniform open round glands
      • Lined by uniform cuboidal to slightly flat cells
      • Nuclei frequently flattened, parallel to circumference of gland
      • Clear to eosinophilic cytoplasm
      • Lumenal eosinophilic colloid-like secretion
        • Occasional luminal calcification
    • Cytologically bland
      • Small indististinct nucleoli
      • Mitotic figures uncommon
    • Haphazard distribution
      • Poorly circumscribed
      • No lobular grouping
      • Not stellate
      • Frequently overruns normal elements
      • No perineural or vascular invasion
    • Background of fibrous or fatty tissue
      • No spindle cell or desmoplastic component
    • No myoepithelial layer
    • Carcinoma, in situ and invasive, has been reported in association with microglandular adenosis
      • Reported in up to 27%
      • Apparently disproportionate numbers of metaplastic, adenoid cystic and basal-like carcinomas
      • Transitional atypical microglandular adenosis has been proposed
        • Increased irregularity and density of glands
        • Increased cytologic atypia
          • Hyperchromasia, prominent nucleoli, apoptosis
        • Increased Ki67 and p53 staining (5-10% of cells)
      • Carcinomas retain the immunophenotype of microglandular adenosis

    Richard L Kempson MD
    Robert V Rouse MD
    Department of Pathology
    Stanford University School of Medicine
    Stanford CA 94305-5342

    Original posting:: May 15, 2006
    Updates: January 20, 2009

    Supplemental studies

    Immunohistology

    S100 100% diffuse
    CK8/18 100%
    EGFR 100%
    EMA Negative
    GCDFP15 Negative
    CK5/6 Negative
    Smooth muscle actin Negative
    ER, PR Negative
    Her2neu Negative
    CD117 Negative
    Collagen type IV Positive basement membrane
    Ki67 <3%
    p53 <3%
    CD117 may be positive in associated CIS or carcinoma
    • Ki67 and p53: 5-10% in microglandular adenosis with atypia, >30% in carcinoma

    Histochemistry

    • Lumenal secretion positive for PASd and other mucin stains

    Differential Diagnosis

    Tubular Carcinoma Microglandular Adenosis
    Stellate, infiltrating Nodular or diffuse
    Round to oval ducts with pointed ends and gaping lumens Uniform small round ducts with small lumens
    Frequent apical snouts No apical snouts
    Empty lumens Eosinophilic secretion present in at least some lumens
    Larger cells, polarized to lumen Cells smaller, flatter
    Round nuclei Nuclei may be flat, parallel to base
    EMA positive EMA negative
    Basement membrane absent Basement membrane variable
    Both have rounded non-branching ducts with a single layer of cells, lacking myoepithelial cells

     

    Sclerosing Adenosis Microglandular Adenosis
    Prominent myoepithelial cells No myoepithelial cells
    Cellular, sclerotic stroma Stroma collagenous or adipose
    Lobular Haphazard
    Compressed lumens Uniform round glands

     

    Apocrine Adenosis Microglandular Adenosis
    Myoepithelial layer present, may be hyperplastic No myoepithelial cells
    Variable size and shape of glands Uniform round glands
    Apocrine lumenal differentiation and in some cases squamous metaplasia present No squamous or apocrine metaplasia
    EMA and GCDFP15 positive EMA and GCDFP15 negative

     

    Microglandular Adenosis Tubular Adenosis
    Uniformly round lumens Predominantly tubular
    Cytoplasm frequently clear Cytoplasm eosinophilic
    No myoepithelial layer Myoepithelial cells present
    Secretion eosinophilic Secretion eosinophilic or basophilic

     

    Microglandular Adenosis Tubular Adenoma
    Poorly circumscribed pattern Circumscribed
    Surrounds normal elements Mass displaces normal elements
    No myoepithelial cell layer Myoepithelial cell layer present
    Haphazardly scattered tubules Densely packed tubules
    Abundant fibrous or fatty stroma Scant stroma

    Clinical

    • Age range 28-82 years
      • Mean about 50 years
    • May be a palpable mass or an incidental finding
    • No metastases reported
    • May recur
      • Very rare aggressive local recurrence
    • Carcinoma may be associated with microglandular adenosis
      • Conservation of immunophenotype and apparent transitional atypical cases support the possibility that microglandular adenosis is a precursor of carcinoma
      • Incidence is unknown but reported as high as 27%
      • Suggests that complete resection is indicated

    Lists

    Adenosis of the Breast

    Bibliography

    • Clement PB, Azzopardi JG. Microglandular adenosis of the breast--a lesion simulating tubular carcinoma. Histopathology. 1983 Mar;7(2):169-80.
    • Tavassoli FA, Norris HJ. Microglandular adenosis of the breast. A clinicopathologic study of 11 cases with ultrastructural observations. Am J Surg Pathol. 1983 Dec;7(8):731-7.
    • Eusebi V, Foschini MP, Betts CM, Gherardi G, Millis RR, Bussolati G, Azzopardi JG. Microglandular adenosis, apocrine adenosis, and tubular carcinoma of the breast. An immunohistochemical comparison. Am J Surg Pathol. 1993 Feb;17(2):99-109.
    • Tavassoli FA, Bratthauer GL. Immunohistochemical profile and differential diagnosis of microglandular adenosis. Mod Pathol. 1993 May;6(3):318-22.
    • Diaz NM, McDivitt RW, Wick MR. Microglandular adenosis of the breast. An immunohistochemical comparison with tubular carcinoma. Arch Pathol Lab Med. 1991 Jun;115(6):578-82.
    • Rosen PP. Microglandular adenosis. A benign lesion simulating invasive mammary carcinoma. Am J Surg Pathol. 1983 Mar;7(2):137-44
    • Khalifeh IM, Albarracin C, Diaz LK, Symmans FW, Edgerton ME, Hwang RF, Sneige N. Clinical, histopathologic, and immunohistochemical features of microglandular adenosis and transition into in situ and invasive carcinoma. Am J Surg Pathol. 2008 Apr;32(4):544-52.
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