Manuel A. Torres-Salichs MD,FACS Surgical Oncology, Breast Surgeon

Edileidis Tarrio, ARNP-BC, OCN





Classification of Invasive Breast Carcinomas

Invasive (Infiltrating) Ductal Carcinoma:
Approximately 80% of the invasive breast cancers are of the ductal type. The cancer cells develop within a breast milk duct. At one point, it erodes through its wall into breast tissue containing blood and lymphatic vessels. It is at this time when cancer cells can potentially spread (metastasize) to other parts of the body.


Invasive Ductal Carcinoma: The cancer cells are no longer confined to the breast ducts. They brake through the basement membrane of the duct and invade the stroma. The blood and lymphatic vessels are located in the stroma. The cancer cells can potentially enter this vessels and spread to other parts of the body.


This breast carcinoma is easily identified in this breast with low density due to its replacement with fatty tissue.

Invasive (Infiltrating) Lobular Carcinoma:
This cancer originates in the milk glands (lobules) of the breast instead of the ductal system. Variants of tumors within this classification have been described based on different types of cells and patterns of infiltration. These include pleomorphic, solid, alveolar, and signet ring. The prognosis ranges from excellent in the classic form of invasive lobular carcinomas to a more aggressive tumor in the case of pleomorphic lobular carcinomas. Invasive lobular carcinoma comprises approximately 10% of invasive breast cancers. For unknown reasons the incidence of this type of tumor is increasing, especially among postmenopausal women. In the 1970’s infiltrating lobular carcinomas constituted 4% of all breast cancer cases. The most recent studies have shown they constitute 10% to 14% of invasive carcinomas. Classic lobular carcinoma is reported to have a better prognosis than infiltrating ductal carcinoma. These tumors are usually located in the upper outer quadrant of the breast and tend to be larger in size. The infiltration of the tumor into the breast tissue does not incite a substantial response.

By virtue of this, lobular carcinomas often fail to form distinct masses that can be easily diagnosed by palpation or mammography. The diminished tissue reaction can make it difficult for surgeons to determine the extent of the disease during surgery and to achieve negative margins of resection. These breast cancers also have a higher incidence of multifocality (multiple deposits of the same cancer cells around the main tumor within the same quadrant of the breast) and multicentricity (multiple tumor deposits throughout the breast). Breast conservation can be challenging sometimes due to these characteristics. There is actually a tendency to favor a mastectomy with this form of breast cancer. Patients with infiltrating lobular carcinoma are especially prone to having bilateral disease. Prior and concurrent carcinoma of the opposite breast has been reported in 6% to 28% of cases. A patient with a history of infiltrating lobular carcinoma can develop another cancer in the opposite breast in approximately 10% to 14% of cases. Metastatic (cancer spreads to other organs) infiltrating lobular carcinoma is more likely to affect the peritoneum, ovaries and gastrointestinal tract than ductal tumors. Central nervous system metastases tend to affect the meninges. The overall survival rate of patients with invasive lobular carcinoma is similar to patients with invasive ductal carcinomas. Both types of breast cancers should be managed similarly and the histologic subtype should not be a deciding factor for the surgical treatment options.


Invasive Lobular Carcinoma. The breast cancer cells originate in the breast lobules. The cells invade the basement membrane of the lobule and colonize the surrounding stroma of the breast tissue. The cancer cells can invade the blood and lymphatic vessels and migrate to other parts of the body.

Inflammatory Breast Carcinoma:
This is the most aggressive type of breast cancer. It accounts for up to 3% of all breast cancers. It usually presents with redness of the skin and the breast is warm. It actually can mimic an infection and the entire breast can become swollen with thickening of the skin. This is due to blockage of the skin lymphatics by the tumor. Inflammatory breast cancer does not present with a breast lump but rather diffuse swelling of the breast. It is sometimes missed by breast imaging studies. The clinical findings are that of dermal edema in one-third or more of the breast, erythema in one-third or more of the breast, and a palpable border to the erythema. It is a tumor that carries a very unfavorable prognosis. Initial staging evaluation is mandatory. This includes a breast MRI and a PET CT scan. Once staging is completed, these women should be treated with preoperative chemotherapy. If these women respond to chemotherapy as the vast majority do, then they should be treated with a total mastectomy, axillary node dissection and radiation therapy.

Mucinous Carcinoma:
This is a rare type of invasive breast carcinoma. It accounts for less than 5% of breast cancer cases. It usually affects women over the age of 60. These tumors produce a substance called mucin that accumulates around the cells. Pools of mucin make up at least one third of the volume of the tumor. When present in its purest form it has an excellent outcome. Lymph node metastases are rare from pure low grade mucinous carcinoma.

Tubular Carcinoma:
This is an uncommon histologic type of breast cancer. Tubular carcinomas represent 3% to 5% of all invasive carcinomas. Generally these are low grade tumors that affect older patients. When this tumor is in its purest form it is highly unlikely to metastasize (spread). Tubular carcinomas have an excellent prognosis.

Cribiform Carcinoma:
The long-term survival is reported to be 100%. Systemic metastases are very rare. This carcinoma is closely related to tubular carcinoma. It is a low grade tumor with an excellent prognosis.

Paget's Disease of the Breast:
This is an unusual presentation of breast carcinoma. It represents less than 4% of breast cancers. There is a higher incidence reported for males. The cancer cells usually originate from the breast ducts and migrate to the nipple. It presents clinically with inflammation, retraction, fissuring, bleeding, and/or eczematous-like changes in the nipple. The patient usually complains of itching and pain. A small percent of patients with Paget disease have no abnormality of the nipple on clinical examination. Nearly all cases of mammary Paget disease are associated with an underlying in situ or infiltrating breast carcinoma.

Medullary Carcinoma:
Medullary breast carcinomas represent 2% of all invasive breast carcinomas. Although these tumors show aggressive pathological characteristics, they are often associated with a more favorable prognosis. Recurrences are very rare more than five years after diagnosis. They respond well to radiotherapy and chemotherapy. This type of tumor is found in association with hereditary breast cancer and a mutation in the BRCA1 breast cancer gene.


This ultrasound image demonstrates a large invasive cancer seen as a dark structure. The edges of this tumor are marked with "X" s. The surrounding breast tissue is seen in gray and white tones.

Less Frequent Types of Tumor

These represent less than 2% of all breast carcinomas:


Adenoid Cystic Carcinoma
Adenosquamous Carcinoma
Apocrine Carcinoma
Invasive Micropapillary Carcinoma
Invasive Papillary Carcinoma
Metaplastic Carcinoma
Small Cell Carcinoma
Secretory Carcinoma
Squamous Cell Carcinoma

New Classification of Breast Tumor Subtypes

Breast cancer is a heterogeneous group of diseases defined by estrogen receptor, progesterone receptor, and HER2 expression. Genetic profiling has been used to identify specific subgroups of breast carcinomas with distinct clinical behavior. This new classification of invasive breast cancers is based on the molecular characteristics of the tumors. The different subtypes of breast cancers have been shown to differ in prognosis and response to treatment.

Luminal Type A

  ER+ &/or PR+, HER2-
  Most common subtype
  Hormone responsive
  Good prognosis

Luminal Type B

  ER+ &/or PR+, HER2+
  • Worse outcome that Luminal A

HER2+ (ER-)

  Less common, aggressive subtype
  High grade histology
  Outcome improved with Herceptin
  Risk at young age


  • Triple negative
  • Aggressive subtype
  • High grade histology
  • Risk at young age
  • More common in African American women
  • Constitute 20% of all breast cancers
  • Propensity for metastasis