A crust on the nipple or areola is a common finding, often resulting from a benign, dried fluid. This crusting represents a buildup of secretions, discharge, or dried skin cells on the surface of the nipple. The underlying cause is usually the temporary leakage of a fluid, which then hardens upon exposure to air. Understanding the source of this dried material helps determine if the crusting is a normal physiological occurrence or a symptom requiring medical attention.
Benign and Hormonal Explanations
The most frequent reasons for nipple crusting are related to normal bodily functions and minor environmental factors. Dried sweat, combined with natural skin oils and exfoliated skin cells, can easily form a minor crust, particularly after exercise or in warm conditions. Friction from tight or coarse clothing, such as a rough bra or athletic wear, can also irritate the delicate skin, leading to minor weeping that dries into a crust.
The areola contains small, raised bumps known as Montgomery glands, which are sebaceous glands that secrete an oily, antimicrobial substance. This natural lubricant can sometimes accumulate and dry on the skin, appearing as a crusty deposit or a waxy plug. These glands often become more noticeable and active due to hormonal fluctuations, such as those occurring during the menstrual cycle or puberty.
Hormones also play a significant role in causing nipple discharge that dries into a crusty layer. During pregnancy, the breast tissue prepares for milk production, and colostrum, a thin, yellowish fluid, may leak, especially in the later stages. This fluid often dries on the nipple surface. Hormonal changes unrelated to pregnancy, or the use of certain medications, can also lead to a physiological discharge from the milk ducts that dries into a crust, a condition often referred to as galactorrhea.
Common Skin Conditions
Nipple crusting is a signature symptom of various inflammatory skin conditions that cause the skin to weep and subsequently dry. Atopic dermatitis, commonly known as eczema, is a chronic condition characterized by a damaged skin barrier function, leading to dry, discolored, and intensely itchy patches. When eczema affects the nipple and areola, the skin can become scaly, cracked, and may ooze a clear fluid that hardens into a crust.
Another frequent cause is contact dermatitis, a localized skin reaction to an irritating substance. This reaction can be irritant (caused by harsh agents like soaps or detergents) or allergic (a response to a product like a new cream). The resulting inflammation causes the skin to break down, leading to fluid leakage and the formation of an intensely itchy, crusty rash. Eczema often affects both breasts, especially in those with a history of the condition, while contact dermatitis depends on direct exposure to the irritating agent.
Infections and Inflammatory Issues
Crusting that results from an infection is typically caused by a discharge containing microbial agents or inflammatory byproducts, such as pus. Yeast infections, primarily caused by the fungus Candida albicans, are common, especially in individuals who are breastfeeding, have diabetes, or have recently taken antibiotics. This infection, often referred to as thrush, thrives in warm, moist environments and can cause the nipple to appear shiny, red, or flaky. The pain is often described as a deep burning or shooting sensation.
Bacterial infections, such as mastitis or an abscess, can also cause a crust to form from purulent discharge. Mastitis is an inflammation of the breast tissue that most commonly affects breastfeeding individuals but can occur in others. The discharge leading to crusting is often accompanied by signs of infection, including localized redness, warmth, significant pain, and sometimes systemic symptoms like fever. Unlike the watery discharge from dermatitis, the crusting from a bacterial infection is often thick and sticky, reflecting the presence of white blood cells.
When to Seek Medical Evaluation
While most nipple crusting is benign, certain associated symptoms indicate the need for a professional medical evaluation. Crusting that is persistent and does not resolve with simple home care, such as gentle cleaning and avoiding irritants, should be discussed with a healthcare provider. The presence of discharge that is bloody, or clear and watery, particularly if it occurs spontaneously and only from a single duct, is a concerning symptom.
A medical consultation is also warranted if the crusting is accompanied by significant pain, swelling, or a palpable lump in the breast or armpit. Changes to the shape of the nipple, such as a recent inversion or flattening, are also important signs to report. These unilateral changes, affecting only one breast, can be associated with rare but more serious conditions, such as Paget’s disease of the breast, a form of cancer that begins in the nipple. Paget’s disease often mimics eczema, presenting as a scaly, crusty rash that does not respond to standard treatments. Another condition is duct ectasia, where a milk duct widens and becomes clogged, causing a thick, sticky discharge that dries into a crust.