Medullary Carcinoma
Epidemiology:
Common sites:
Gross features:
- well-circumscribed
mass
- soft, fleshy
consistency
Histologic features:
- solid, syncitium-like sheets occupying >75% of tumour
- poorly
differentiated by definition
- large cells
- vesicular, pleomorphic nuclei
- frequent mitoses
- lymphoplasmacytic infiltrate surrounding and within
the tumour
- pushing border
Immunophenotype:
Marker:
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Sensitivity:
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Specificity:
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ER, PR (neg)
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Molecular features:
- aneuploid
- no HER2/neu overexpression
- hypermethylation of BRCA1 promoter (67%)
- familial:
Other features:
- slightly better
prognosis than NST
- lymph node mets are infrequent
- may be mistaken
clinically for a fibroadenoma
- often rapid,
almost explosive growth
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