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Synonyms and keywords: Intraductal hyperplasia; IDH; Atypical ductal hyperplasia; Comedocarcinoma; Duct cell carcinoma; Duct carcinoma

# Overview
Ductal carcinoma is the most common type of breast cancer in women. Ductal carcinoma may be classified according to the Armed Forces Institute of Pathology (AFIP) into 2 groups: large cell carcinoma in situ and small cell carcinoma in situ. The pathogenesis of ductal carcinoma is characterized by the microinvasion of cancer cells limited to the ducts with no extension beyond the basement membrane. The mutation on HER2/neu has been associated with the development of ductal carcinoma.

# Historical Perspective
Ductal carcinoma was first described in 1893.

# Classification
- Ductal carcinoma may be classified according to the Armed Forces Institute of Pathology (AFIP) into 2 groups:
- Large cell
- More aggressive form
- Also referred to as comedocarcinoma
- Small cell
- Less aggressive
- Subtypes include cribriform, micropapillary, papillary, and solid in situ.
- Other variants of ductal carcinoma include, non-DCIS entities.

# Pathophysiology
- The pathogenesis of ductal carcinoma is characterized by the microinvasion of cancer cells limited to the ducts with no extension beyond the basement membrane.
- The mutation on HER2/neu has been associated with the development of ductal carcinoma.
- On gross pathology, characteristic findings of ductal carcinoma, include:
- White
- Firm stellate lesion
- On microscopic histopathological analysis, characteristic findings of ductal carcinoma, include:
- Equal spacing of cells - "cookie cutter" look.
- Cells line-up along lumen/glandular spaces - form "Roman briges".
- Nuclear enlargement (key feature)

# Causes
- Common causes of ductal carcinoma,  may include:

# Differentiating ductal carcinoma from other Diseases
- Ductal carcinoma must be differentiated from other diseases that cause nipple discharge, breast skin color change, and palpable mass such as:

# Epidemiology and Demographics
- The prevalence of ductal carcinoma is approximately 32.5 per 100,000 women worldwide.

## Age
- Ductal carcinoma is commonly observed among females between 40 to 80 years old
- Ductal carcinoma is rarely observed among males between 60 and 70 years of age
- Ductal carcinoma is more commonly observed among postmenopausal women

## Gender
- Females are significantly more commonly affected with ductal carcinoma than males.

## Race
- There is no racial predilection for ductal carcinoma.

# Risk Factors
- Common risk factors in the development of ductal carcinoma, include:
- Family history of breast cancer
- Mutations in BRCA1/BRCA2 genes
- Previous exposure to radiation therapy
- Increased breast density
- Hormonal therapy
- Nulliparity
- Obesity

# Natural History, Complications and Prognosis
- The majority of patients with ductal carcinoma remain asymptomatic for years.
- Early clinical features include skin color change or nipple discharge.
- If left untreated, the majority of patients with ductal carcinoma may progress to develop lymph node invasion, and metastasis.
- The most common complication of ductal carcinoma is lymphedema.
- Prognosis generally depends on the histological subtype.
- In general, the 20-year mortality rate among patients with ductal carcinoma is approximately 3.3%.
- Factors related with worse prognosis, include: young age at diagnosis, black ethnicity, and high grade cancer.

# Diagnosis

## Diagnostic Criteria
- The diagnosis of ductal carcinoma is made when at least  of the following  diagnostic criteria are met:

## Symptoms
- Ductal carcinoma is usually asymptomatic.
- Symptoms of ductal carcinoma may include the following:
- Nipple discharge
- Skin color changes
- Warm and thickened
- Skin of an orange appearance
- Nipple retraction

## Physical Examination
- Patients with ductal carcinoma usually are well-appearing.
- Physical examination may show no specific physical findings.
- In some cases, it may be remarkable for:
- Palpable mass

## Laboratory Findings
- Laboratory findings consistent with the diagnosis of ductal carcinoma, include:
- Positive/negative estrogen receptor (ER) and progesterone receptor (PR) expression

## Imaging Findings
- Mammography is the imaging modality of choice for ductal carcinoma.
- On mammography, findings of ductal carcinoma,  include:
- Calcifications (most common)
- Simple mass
- Soft-tissue opacity
- Asymmetry without calcification
- The image below demonstrates findings compatible with  ductal carcinoma.
- Normal (left) versus cancerous (right) mammography image.

## Other Diagnostic Studies
- Ductal carcinoma may also be diagnosed using .
- Findings on  include , , and .

# Treatment

## Medical Therapy
- The mainstay of therapies for ductal carcinoma are divided into 2 groups: hormonal therapy and targeted therapy.
Hormonal Therapy
- Selective estrogen receptor modulators, such as:
- Tamoxifen
- Raloxifene
Targeted Therapy
- HER2-directed therapy
- Trastuzumab
- The primary goal of medical therapy is to reduce the risk of ipsilateral or contralateral breast invasion and also decreases the risk of recurrence.
- Response to medical therapy can be monitored with  every .

## Surgery
- Surgery is the mainstay of therapy for ductal carcinoma.
- Surgical approaches for ductal carcinoma, include: mastectomy or breast-conserving therapy
-  in conjunction with  is the most common approach to the treatment of ductal carcinoma.
-  can only be performed for patients with  ductal carcinoma.

## Prevention
- Effective measures for the secondary prevention of ductal carcinoma include: screening mammography for women between 50-74 years (or earlier if identified risk factors)  and periodical breast self-examination (BSE). 
- Once diagnosed and successfully treated, patients with ductal carcinoma are followed-up every 3, 6, or 12 months depending on individual assessment.