Invasive breast carcinoma of no special type and variants


Topic Completed: 1 December 2017

Minor changes: 25 October 2021

Copyright: 2003-2021,, Inc.

PubMed Search: Medullary [title] carcinoma breast NOT thyroid

Mirna B. Podoll, M.D.
Emily S. Reisenbichler, M.D.
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Cite this page: Podoll MB, Reisenbichler ES. Medullary. website. Accessed October 25th, 2021.
Definition / general
  • Carcinoma with medullary features (CMF) includes medullary carcinoma, atypical medullary carcinoma and invasive carcinoma, no special type (NST) with features of pushing borders, syncytial growth, high grade nuclei and prominent lymphoid infiltrate
  • Subset of triple negative (ER-, PR-, HER2-) breast carcinoma
  • Medullary carcinoma represents < 1%, however up to 20% of invasive breast cancers reportedly have some medullary features
  • Most common type of breast carcinoma in patients with BRCA1 germline mutation
  • Show increased expression of cell adhesion proteins
Essential features
  • Well circumscribed, composed of high nuclear grade cells with syncytial or large sheet-like growth, pushing borders, prominent lymphoplasmacytic infiltrate, scant fibrous stroma, no glandular structures and minimal DCIS
  • Circumscribed borders mimic benign lesions on imaging
  • Soft in consistency due to the lack of desmoplastic response
  • WHO Classification of Tumors of the Breast (2013) recommends using the term Carcinoma with medullary features (CMF) rather than medullary carcinoma or atypical medullary carcinoma
  • This terminology is recommended due to the lack of reproducibility in the diagnosis of medullary carcinoma and to avoid undertreatment of aggressive triple negative tumors lacking some diagnostic features of medullary carcinoma
  • 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)
  • Most commonly affects women 45 - 52 years
  • Accounts for 30 - 60% of breast tumors in patients with BRCA1 germline mutation
  • Rare in patients with BRCA2 germline mutation
Clinical features
  • Typically present as a soft palpable circumscribed mass which may appear benign
  • Lymphadenopathy may be present (due to hyperplasia rather than metastasis, which is uncommon)
Radiology description
  • Round, oval or lobulated mass on mammography
  • Hypoechoic mass on ultrasound with thick echogenic halo is commonly seen
Prognostic factors
  • Tumors with dense lymphocytic infiltrates are more likely to respond to chemotherapy
  • CMF has better prognosis than stage matched triple negative carcinoma
  • 10 year survival rates can be > 80%
  • Favorable prognosis may not apply to tumors > 3 cm, with nodal metastases or with BRCA1 mutations
  • When lymph node metastasis are present (≥ 4 nodes), recurrence / death within 5 year period is common
  • Slightly better prognosis than invasive ductal carcinoma NOS, even though high grade, aneuploid, ER / PR negative, p53 positive and high proliferation rates (Hum Pathol 1988;19:1340, Int J Radiat Oncol Biol Phys 2005;62:1040)
  • Better prognosis may be due to prominent inflammation (Eur J Cancer 2009;45:1780, Mod Pathol 2010;23:1357)
Case reports
  • Complete excision is recommended
  • Adjuvant chemotherapy and radiation are recommended similar to other triple negative tumors and invasive carcinoma respectively
Clinical images

Contributed by Mark R. Wick, M.D.


Gross description
  • Well circumscribed, 2 - 3 cm in size, soft and fleshy (may resemble fibroadenoma)
  • Homogenous with white to gray appearance
  • May show areas of necrosis with are focal and can cause cystic degeneration
Gross images

Contributed by Mark R. Wick, M.D.

Various images

AFIP images

Sharply defined margin
with internal nodularity
and bosselated surface

Images hosted on other servers:

Well circumscribed partly cystic gray-white

Atypical medullary carcinoma: primary and nodal metastases

Gray fleshy tumor

Tannish pink tumor with circumscribed margin

Tumor with extensive hemorrhage

Microscopic (histologic) description
  • Sharply circumscribed and pushing borders
  • Sheets of cells with indistinct cell borders (syncytial growth) in greater than 75% of tumor
  • Moderately to poorly differentiated; no prominent tubule formation
  • Pleomorphic cells with large nuclei and prominent nucleoli (cells may have multiple nucleoli)
  • Numerous mitoses with atypical mitoses
  • Moderate to marked lymphoplasmacytic response at periphery consists of cytotoxic T cells (CD3+ and CD8+) and IgA plasma cells
  • T cell infiltrate can be seen surrounding lobules in the background breast tissue
  • May contain multinucleated giant cells, squamous metaplasia, geographic necrosis, hemorrhage
  • Uncommon: lymphovascular invasion, lymph node involvement, DCIS
  • No desmoplastic reaction
Microscopic (histologic) images

Contributed by Mirna B. Podoll, M.D.
Missing Image

Carcinoma with medullary features

Prominent cellular pleomorphism

High grade features

Low power showing marked lymphocytic response

AFIP images

Medullary features

A lobule with in situ carcinoma in some lobular units

Focal areas of squamous metaplasia with keratin pearls

Tumor invades fat; is not well circumscribed

Contributed by Mark R. Wick, M.D.

Various images

Images hosted on other servers:

High grade syncytial pattern

Atypical medullary carcinoma

ER negative



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 carcinoma
  • 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
  • Lymph node in axillary tail: not circumscribed and may not be syncytial
    • While germinal centers can be seen in CMF and are not evidence of lymph node, a lymph node capsule or subcapsular sinus is supportive of lymph node
  • Lymphoma: primary breast lymphomas are more commonly B cell derived, CMF has predominantly T cells and plasma cells; tumor cells will stain with cytokeratins
  • EBV associated lymphoepithelial-like carcinoma: will display infiltrative borders and is EBV positive while only a few cases of CMF have been found to have EBV positivity
  • Undifferentiated ductal carcinoma: lacks prominent lymphoplasmacytic infiltrate, has infiltrative borders
Board review style question #1
    Which of the following is true of invasive carcinoma with medullary features?

  1. Are high grade triple negative tumors.
  2. Have a prominent lymphocytic infiltrate of predominantly B cells.
  3. Most commonly present as calcifications on mammography.
  4. Patients usually have poor prognosis.
  5. They are commonly infiltrative masses.
Board review style answer #1
A. Breast carcinoma with medullary features (CMF) most commonly presents as a palpable well circumscribed mass that may mimic benign lesions. They are high grade and demonstrate a prominent lymphocytic infiltrate predominantly of CD3 and CD8 positive T cells. Despite being triple negative, patients with CMF tend to have better prognosis than grade matched invasive carcinoma of no special type.

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Reference: Carcinoma with medullary features (CMF)
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