Breast malignant, males, children
Carcinoma subtypes
Medullary carcinoma

Author: Monika Roychowdhury, M.D. (see Authors page)

Revised: 29 December 2016, last major update August 2012

Copyright: (c) 2002-2016,, Inc.

PubMed search: medullary [title] carcinoma breast NOT thyroid

Cite this page: Medullary carcinoma. website. Accessed October 23rd, 2017.
Definition / general
  • Well circumscribed, composed of poorly differentiated cells in syncytia or large sheets, with prominent lymphoplasmacytic infiltrate, scant fibrous stroma, no glandular structures, minimal DCIS
  • Considered a type of basal-like carcinoma (Breast Cancer Res 2007;9:R24, Am J Surg Pathol 2007;31:501)
  • "Medulla" refers to soft structure of marrow (tumors are often soft)
Clinical features
  • Uncommon, < 1% of invasive breast carcinomas
  • Usually < 50 years old, often < 35 years old, common in Japanese, associated with BRCA1 mutations
  • More activated cytotoxic lymphocytes than poorly differentiated ductal carcinomas (Mod Pathol 1999;12:1050, Mod Pathol 2008;21:1101)
Prognostic factors
Case reports
Clinical images

Images hosted on PathOut server:

Mammogram, courtesy of Dr. Mark R. Wick

Gross description
  • Well circumscribed, often large, resembles fibroadenoma but without whorls
  • Soft, fleshy, tannish gray
  • No desmoplasia
  • Easy to cut, large areas of necrosis and hemorrhage
Gross images

Images hosted on PathOut server:

Courtesy of Dr. Mark R. Wick

Sharply defined margin
with internal nodularity
and bosselated surface

Images hosted on other servers:

Well circumscribed partly cystic grey white

Atypical medullary carcinoma: primary and nodal metastases

Gray fleshy tumor

Tannish pink tumor with circumscribed margin

Tumor with extensive hemorrhage

Well circumscribed and may be partially cystic

Flickr images:

Locally advanced 7 cm tumor

Microscopic (histologic) description
  • Indistinct cell borders (syncytial growth) making up 75%+ of tumor with large pleomorphic tumor cells containing large nuclei, prominent nucleoli, numerous mitotic figures; peripheral cells are more eosinophilic
  • Prominent lymphoplasmacytic infiltrate at periphery composed of T cells and IgA plasma cells
  • Pushing borders / well circumscribed
  • Classify as medullary carcinoma if tumor has above three features
  • Classify as atypical medullary carcinoma (or infiltrating ductal carcinoma) if tumor has only 2 of 3 features listed above (atypical medullary carcinoma has similar prognosis as ductal carcinoma NOS)
  • Other features:
    • Sparse stroma
    • Variable spindle cell or squamous metaplasia, occasional bizarre tumor giant cells and extensive necrosis
    • No / minimal glandular differentiation, no intraductal growth or DCIS, no mucin, no calcification
Microscopic (histologic) images
Scroll to see all images.

Images hosted on PathOut server:

Courtesy of Dr. Mark R. Wick

AFIP images:

Tumor cells

A lobule with in situ carcinoma in some lobular units

Focal areas of squamous metaplasia with keratin pearls

AFIP - Atypical medullary carcinoma:

Tumor invades fat; is not well circumscribed

Medullary features

Images hosted on other servers:

More distinct cell borders

Clusters of sheets of syncytial cells with prominent lymphoplasmacytic infiltrate

Various images

High grade syncytial pattern

FISH and IHC show HER2 amplification

Atypical medullary
carcinoma because
no lymphoplasma-
cytic infiltrate

Flickr images:

ER negative



CISH, heterogeneous
expression of HER2,
various images

HER2 staining (usually is negative, in this case, is focally 3+ [see image on right])

Cytology description
Cytology images

Images hosted on other servers:


Atypical medullary carcinoma

Positive stains
Molecular / cytogenetics description
  • Microsatellite instability is uncommon, in contrast to medullary colonic tumors (Am J Clin Pathol 2001;115:823)
  • Similar genetic alterations as basal-like carcinomas
  • Usually aneuploid
  • Associated with BRCA1 mutations

Histopathology Breast—Medullary carcinoma
Differential diagnosis
  • Collision tumor of invasive ductal NOS and MALT lymphoma: see Arch Pathol Lab Med 2004;128:99
  • Lymphoepithelioma-like carcinoma: has infiltrative borders
  • Lymph node in axillary tail: not circumscribed and may not be syncytial
  • Undifferentiated ductal carcinoma: lacks prominent lymphoplasmacytic infiltrate, has infiltrative borders