Nipple Discharge

Definition of nipple discharge:
- Fluid that leaks from one or both nipples is called a nipple discharge:
  - Each breast has several (15 to 20) milk ducts:
    - A discharge can come from one or more of these ducts
Nipple discharge accounts for approximately 2% to 10% of the symptoms that women report when they seek care at breast clinics:
- Causing anxiety in patients because it can be a presenting sign of breast cancer:
  - However, it is usually benign in origin (papillomas and galactophore / mammary duct ectasia):
    - With a 5% to 21.3% risk of an underlying malignant lesion:
      - Mostly due to in situ carcinomas
Nipple discharge can occur normally during the last weeks of pregnancy and after childbirth:
- When breast milk is produced
A nipple discharge can also be normal in women who are not pregnant or breastfeeding:
- Especially during the reproductive years:
  - For example, in women, fondling, suckling, irritation from clothing, or sexual arousal can stimulate a nipple discharge, as can stress:
    - However, a nipple discharge in men is always abnormal
A normal nipple discharge is usually:
- A thin, cloudy, whitish, or almost clear fluid that is not sticky:
  - However, the discharge may be other colors, such as gray, green, yellow, or brown
- During pregnancy or breastfeeding:
  - A normal discharge is sometimes slightly bloody
If the discharge is considered to be physiologic on the basis of clinical information and characteristics of the nipple discharge:
- No further imaging studies of the breast are warranted:
Although approximately 80% to 90% of patients with pathologic nipple discharge have been reported to have benign conditions:
- Breast imaging enables the localization of the breast abnormalities causing the pathologic nipple discharge:
  - Which helps minimize the number of operations and / or the extent of surgery
  - In addition, localizing the origin of pathologic nipple discharge enables percutaneous biopsy under imaging guidance:
    - Which allows clinicians to be more confident when deciding upon management and when choosing whether to perform minimally invasive percutaneous vacuum-assisted excision
Abnormal discharges vary in appearance depending on the cause:
- An abnormal discharge may be accompanied by other abnormalities:
  - Such as dimpled skin, swelling, redness, crusting, sores, and a retracted nipple:
    - A nipple is retracted if it pulls inward and does not return to its normal position when it is stimulated
- If a discharge from only one breast occurs on its own (without any stimulation of the nipple):
  - It is considered abnormal
Causes:
- Several disorders can cause an abnormal discharge:
  - A discharge from one milk duct or from one breast:
    - Is likely to be caused by a problem with that breast:
      - Such as a noncancerous (benign) or cancerous breast tumor
  - A discharge from both breasts or from several milk ducts in one breast is more likely to be caused by a problem outside the breast:
    - Such as a hormonal disorder or use of certain drugs
Common causes of a nipple discharge:
- Usually, the cause is a benign disorder of the milk ducts, such as the following:
  - A benign tumor in a milk duct (intra ductal papilloma):
    - Intra ductal papilloma is the most common cause
    - It is also the most common cause of a bloody nipple discharge when there is no lump in the breast
  - Dilated milk ducts (mammary duct ectasia)
  - Fibrocystic changes:
    - Including pain, cysts, and general lumpiness
  - A breast infection or abscess
  - Less common causes of a nipple discharge:
    - Certain disorders stimulate the production of breast milk in women who are not pregnant or breastfeeding:
      - In most of these disorders, the level of prolactin (a hormone that stimulates production of breast milk) is elevated:
        Taking certain drugs can have the same effect
    - Cancer causes fewer than 10% of cases:
      - Nipple discharge is a cause for concern when it:
        Occurs without the nipple’s being squeezed or stimulated by other means (when it occurs spontaneously)
        Occurs in women aged 40 or older
        Comes from only one breast
        Is bloody or pink
        Is accompanied by a lump that can be felt
        Occurs in a boy or man
Preferred examination:
- Mammography or digital breast tomosynthesis (DBT):
  - Is the first-line study for a pathologic discharge in most patients:
    - Mammography is limited:
      - Because of its poor sensitivity of 20% to 25%
      - A negative mammogram in the context of nipple discharge:
        Does not therefore exclude any underlying disease:
- Ultrasound is performed immediately after mammography even if the mammogram is normal
According to the American College of Radiology (ACR) Appropriateness Criteria:
- For women 30 to 39 years of age:
  - Either mammography or ultrasonography may be used as the initial examination
- For women aged 30 years or younger:
  - Ultrasound should be the initial examination:
    - With mammography / DBT added when ultrasound shows suspicious findings or if the patient is predisposed to developing breast cancer
- For men aged 25 years or older:
  - Mammography / DBT should be, performed initially:
    - With ultrasound added as indicated, given the high incidence of breast cancer in men with pathologic nipple discharge
- Although MRI and ductography (galactography) are not usually appropriate as initial examinations:
  - Each may be useful when the initial standard imaging evaluation is negative