Pathology Associates Of Lexington, P.A.
Pathology Associates Of Lexington, P.A.
Pathology Associates Of Lexington, P.A.
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        Breast, Microglandular Adenosis (MGA)
      
Microglandular Adenosis
First described by McDivitt in 1968, there is concern that...especially when atypical...this lesion (MGA) represents a premalignant state1, 2. Take great care to distinguish MGA (which should be excised) from ordinary adenosis [LMC-01-6487] and secretory adenosis (ordinary adenosis has  ME cells, S100 neg. epithelials,  and a lobulated pattern).

  • Banal, Ordinary MGA:
    1. Treatment: excision with clear margin1
    2. Histology: almost always diffuse/disordered proliferation of small round tubular profiles...even into fat...with lumens containing PAS+ secretion, thickened BMs, each acinus distinctly circumscribable
    3. Cytology: mitoses rare, fairly regular nuclei with inconspicuous/unapparent nucleoli
    4. IHC1:
      • epithelials are S100+2
      • ER, PR, and HER2  neg.
      • no ME cells
      • BM+ for laminin and/or type IV collagen
      • EMA neg. (tubular ca. always EMA+)
  • Atypical MGA:
    1. Treatment: excision with "widely clear" margin1
    2. Histology: smaller lumens, and acinar budding & complexity and sharing of walls
    3. Cytology: more atypia; more mitotic
    4. IHC: same as banal MGA
References:

  1. Rosen's Breast Pathology, text, 1997
  2. Tavassoli seminar at MCG 21 April 2001, handout
 
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