Nipple bleeding: causes and examination

Bloody nipple discharge is considered a pathological condition. Doctors are primarily concerned if the discharge is spontaneous (occurs on its own), unilateral, and originates from a single duct. This condition is most often associated with a localized intraductal process—either benign (for example, intraductal papilloma) or malignant (ductal carcinoma in situ/invasive), so the situation requires routine, but immediate, diagnosis. [1]

It's important to understand that most cases of abnormal discharge are due to benign causes. According to major reviews and ACR criteria, intraductal papillomas and ductal ectasia are the most common; the proportion of cancers in patients undergoing surgical evaluation varies between 5% and 23%, depending on the selection and methodology. This is a high threshold for caution, but far from a death sentence—which is why staged imaging and targeted biopsy have become the standard. [2]

Bloody discharge can also occur due to dermatological problems in the nipple-areolar area (trauma, cracked eczema), especially with scratching. However, if blood is visible as a drop from a nipple pore without trauma to the surrounding skin, this indicates a ductal source. During the examination, the doctor tries to distinguish cutaneous "bleeding" from true intraductal discharge. [3]

A separate, rare but important cause is Paget's disease of the nipple (cancer "masquerading" as nipple eczema). It is usually unilateral and may be accompanied by crusting, itching, and discharge, and therefore any persistent "eczema" of one nipple, especially with blood, is considered an indication for oncorouting and, if necessary, biopsy. [4]

Main causes: from benign to serious

Most often, bloody discharge is caused by intraductal papillomas—small benign "polyps" within the milk duct. They tend to bleed and produce clear or bloody discharge. Although papillomas themselves are benign, atypia is sometimes found within them; therefore, when detected, the lesion is usually removed or at least morphologically confirmed by needle biopsy/vacuum-assisted biopsy. [5]

The second most common diagnosis is ductal ectasia (dilation and inflammation of large ducts). It often produces serous/brownish discharge, but can also develop into a pinkish-bloody color. It is usually benign, more common in perimenopausal women; treatment includes observation, treatment of inflammation, and, in cases of focal lesions, targeted biopsy/excision. [6]

Malignant causes include ductal carcinoma in situ and invasive cancer, including the rare Paget's disease. The classic "suspicious" presentation is unilateral, spontaneous, often clear/bloody discharge from one nipple orifice, sometimes accompanied by a palpable nodule or new skin lesions. Modern imaging algorithms have been optimized for this clinical presentation. [7]

Non-ductal sources are also considered: cracked nipples during breastfeeding, injuries (including sports friction), dermatitis, food and drug factors, and rare vascular/infectious causes. However, with "true" ductal bleeding, these options remain second on the list – they are excluded by skin examination and medical history. [8]

Red flags and when to see a doctor

Seek medical attention promptly and without delay if the discharge is bloody or clear, occurs spontaneously, is from one breast, and/or appears to be from one nipple opening. Even with a high probability of benignity, such cases require evaluation by a mammologist/radiologist with experience in treating abnormal discharge. [9]

Seek immediate medical attention if the bloody discharge is accompanied by a new lump/nodule, skin or nipple indentation, "orange peel" appearance, persistent nipple eczema, or enlarged axillary nodes. This does not automatically indicate cancer, but it does increase the pre-test probability of malignancy and expedite the examination. [10]

In men, any nipple discharge, especially bloody discharge, is considered abnormal and requires examination. Pregnant and breastfeeding women experience their own benign scenarios (like "rusty tube" - bloody colostrum at the beginning of lactation), but a doctor will still rule out ductal pathology if the discharge persists or appears "abnormal." [11]

If "blood on underwear" is due to cracked skin or scratches on the areola/nipple, that's a different matter: the skin should be treated first and any friction/contact dermatitis eliminated. But if there's any doubt about the source, it's best to check: an examination with gentle pressure and visualization will show whether blood is coming from the duct. [12]

How they survey: what really works in 2024-2025

The first step is clinical triage: distinguishing physiological/cutaneous causes from pathological intraductal ones. "Physiological" (milky/greenish, bilateral, non-spontaneous, multiductal) usually requires no more than age-appropriate screening mammography. "Pathological" (unilateral, spontaneous, single-ductal, clear/bloody) - requires targeted imaging. [13]

The basic combination is diagnostic mammography and retroareolar ultrasound. Mammography looks for calcifications/masses, while ultrasound detects ductal lesions, papillomas, and cysts, and helps guide a targeted needle biopsy. If these methods are negative, but the clinical picture of a "pathological" discharge persists, the next step is most often an MRI of the mammary glands—a sensitive method that allows for the visualization of lesions and subsequent MRI-guided biopsy. MRI is increasingly replacing ductography in complex cases. [14]

If a lesion is visualized, a core biopsy (often vacuum-assisted biopsy - VABB) is indicated, which not only clarifies the diagnosis but sometimes completely removes a small intraductal nodule. This approach reduces the number of "just in case" surgeries and provides a quicker answer. If a lesion is not found and the discharge is persistent, decisions are made on an individual basis, ranging from observation with MRI guidance to ductoscopy/surgical microductectomy. [15]

An important detail: color isn't always decisive. Although blood is a strong marker, some malignant processes manifest as clear/serous discharge, and vice versa: not everything "red" is cancer. Therefore, a combination of characteristics (spontaneity, unilaterality, single-ductality) and the results of staged visualization are used. [16]

Treatment: from observation to mini-operations

If an intraductal papilloma without atypia is confirmed, options include observation after complete vacuum-assisted biopsy excision or sectoral excision of the duct (microductectomy) if discharge persists. If atypia or suspicious findings are detected, surgical excision with morphology is indicated to exclude adjacent in situ/invasive carcinoma. [17]

In cases of ductal ectasia, anti-inflammatory and local therapy, observation, and correction of factors (smoking, hormonal influences) are often sufficient; in cases of recurrence or persistent discharge, targeted excision of the dilated duct is performed. This solves the problem and eliminates the symptom. [18]

If imaging and/or biopsy reveal cancer (ductal in situ or invasive), treatment follows oncology standards: surgery (organ-preserving or mastectomy) with nodule assessment, radiation therapy, and systemic treatment based on the tumor's biology. For Paget's disease, the strategy depends on the extent and presence of an underlying lesion: organ-preserving options with radiation therapy or mastectomy are possible. [19]

When are niche technologies used? Ductoscopy (duct endoscopy) is used in select centers for source localization and pinpoint excision. Liquid-based cytology of discharge using modern techniques is being actively researched; early studies report promising sensitivity, but for now it is a complement to, not a replacement for, biopsy/MRI. [20]

Special situations: pregnancy/lactation, men, "blood and skin"

During pregnancy and early lactation, the phenomenon of "rusty pipe"—a brownish, bloody discharge due to fragile blood vessels in the ducts and hormonal changes—occurs. It usually resolves within a few days or weeks. However, if the discharge is one-sided, persistent, and abnormal, a mild radiation (safe) diagnostic procedure is performed: ultrasound is the first step, followed by further evaluation based on indications and standards for pregnant women. [21]

In nursing mothers, the appearance of blood on pads is often explained by cracked nipples. Here, the focus is on treating the skin and correcting the latch; if the sensation of blood coming from a nipple pore persists, follow the algorithm for pathological discharge (retroareolar ultrasound, then follow the results). This is important because intraductal lesions can also exist during lactation. [22]

In men, any discharge, especially bloody, is abnormal. The procedure is the same: examination, mammography/ultrasound, and targeted biopsy if a lesion is present. Although less common, men can have both papillomas/ectasia and carcinoma; therefore, delay is not justified. [23]

If "blood on the nipple" is associated with eczema/dermatitis or mechanical irritation (sports, tight underwear), the skin is treated with barrier creams, short-term topical anti-inflammatory agents, and friction control. However, if the source is unclear, imaging is preferable to confidently rule out ductal pathology. [24]

Prognosis, observation and self-care

For benign causes (papilloma without atypia, ectasia), the prognosis is excellent: after local treatment/excision, recurrences are rare, and quality of life is quickly restored. If the lesion is removed entirely by vacuum biopsy, observation without surgery is possible – a decision made in consultation with a physician, taking into account the morphology and symptoms. [25]

In malignant diagnoses, the outcome is determined by the stage and biology of the tumor. A benefit for the patient is that bloody discharge often highlights early intraductal lesions, which respond well to organ-preserving treatment with excellent disease control. Modern radiation therapy and drug treatment regimens help preserve breast shape and reduce the risk of recurrence. [26]

After eliminating the cause, the doctor discusses a monitoring plan: examinations, follow-up imaging (ultrasound/mammography/sometimes MRI), and markers for rapid recovery (the appearance of new spontaneous discharge, nodule, or skin changes). It's important to understand that the "color" of the discharge itself is not a key indicator—its spontaneity and single-duct nature are more important. [27]

Self-care includes avoiding nipple squeezing/checking (this maintains discharge), gentle skin care, wearing appropriately sized underwear, and seeking medical attention at the first sign of an abnormal condition. For nursing mothers, this includes working on latching technique and protecting the skin barrier to avoid masking true ductal symptoms with cracks. [28]

Brief FAQ

Is it always cancer?
No. The most common causes are intraductal papilloma and ductal ectasia. The risk of malignancy in surgical series is approximately 5-23%, so testing is essential, but panic is not. [29]

How does the examination begin?
With an examination and diagnostic mammography plus retroareolar ultrasound. If they find nothing, but the clinical picture is "pathological," they add an MRI; if there is a lesion, a needle/vacuum biopsy with possible "complete" removal of small nodes. [30]

If it's a papilloma, is surgery necessary?
Most often, yes, but if it's completely removed by vacuum biopsy and there's no atypia, observation is an option. The decision is individual and depends on symptoms and morphology. [31]

What if the discharge is clear, not bloody?
If it's spontaneous, unilateral, and from a single duct, the algorithm is the same: it's pathological discharge, and it's examined as a potential marker of intraductal pathology. [32]