Paget’s disease of the breast is a rare form of breast cancer that appears on the skin of the nipple and areola. It accounts for 1% to 3% of all breast cancers and occurs mostly in postmenopausal women. What makes it unusual is that it looks like a skin condition, not cancer. The nipple develops eczema-like changes that can persist for weeks or months before the correct diagnosis is made.
Despite its innocent appearance, Paget’s disease is almost always connected to cancer deeper in the breast. Between 93% and 100% of cases are associated with an underlying breast cancer, most commonly ductal carcinoma in situ (an early, non-invasive form) or invasive ductal carcinoma.
How It Looks and Feels
The symptoms of Paget’s disease center on the nipple and the ring of darker skin around it (the areola). Common changes include:
- Itching, tingling, or redness of the nipple or areola
- Flaking, crusty, or thickened skin on or around the nipple
- A nipple that becomes flattened or inverted
- Discharge from the nipple, which may be yellowish or bloody
Some people also have a lump or mass in the same breast. In a study from M.D. Anderson Cancer Center, 60% of patients with Paget’s disease had invasive cancer in the breast, 33% had non-invasive cancer, and only 7% had disease confined entirely to the nipple with no deeper involvement.
Why It’s Often Mistaken for Eczema
Because the early signs look so much like eczema or dermatitis, many people (and even some clinicians) initially treat it as a skin problem. The key difference is that Paget’s disease does not improve with standard skin treatments. Eczema of the nipple typically responds to moisturizers or topical steroids within a couple of weeks. When those treatments fail and symptoms persist or worsen, that resistance to treatment is itself a red flag pointing toward Paget’s disease.
Another distinguishing feature: nipple eczema tends to affect both breasts and often spares the nipple itself, while Paget’s disease almost always starts on one nipple and spreads outward to the areola.
What’s Happening Inside the Breast
Under a microscope, the affected nipple skin contains large, distinctive cancer cells called Paget cells. These cells have pale, abundant interiors and oversized, irregularly shaped nuclei. They scatter through the surface layer of the nipple skin, either individually or in clusters.
Scientists have two main theories about where these cells come from. The more widely accepted one, called the epidermotropic theory, proposes that cancer cells originate in the milk ducts deeper in the breast and migrate outward along the duct system until they reach the nipple surface. This would explain why the vast majority of Paget’s cases have underlying breast cancer. The second theory suggests that skin cells of the nipple transform into cancer cells independently, which may account for the small number of cases with no deeper tumor.
About 80% to 90% of Paget’s disease cases overexpress a protein called HER2, which promotes cancer cell growth. This is a significantly higher rate than breast cancer overall, where roughly 15% to 20% of cases are HER2-positive. This molecular profile matters because it opens the door to targeted therapies that block HER2.
How It’s Diagnosed
Diagnosis requires a skin biopsy of the nipple. A small sample of the affected skin is removed and examined under a microscope, where Paget cells are readily identifiable. This is a straightforward procedure, and it provides a definitive answer.
Once the skin biopsy confirms Paget’s disease, imaging is needed to check for cancer elsewhere in the breast. This typically involves a combination of tools:
- Mammography looks for abnormalities like microcalcifications or masses, but it comes back normal in about 50% of Paget’s cases, so a clean mammogram does not rule out deeper disease.
- Ultrasound helps determine whether a breast lump is solid or fluid-filled and can reveal tumors that mammography misses.
- Breast MRI provides the most detailed picture and is now considered a standard part of the workup for Paget’s disease. It can detect additional areas of cancer in the affected breast or in the opposite breast.
If imaging reveals a suspicious area in the breast tissue, a needle biopsy guided by imaging is performed to sample that tissue separately.
Surgical Treatment Options
Surgery is the primary treatment. The type of operation depends on how much of the breast is involved and where the underlying cancer is located.
When the disease is limited to the nipple area or involves a small, localized tumor, breast-conserving surgery is an option. This removes the nipple, areola, and a margin of surrounding tissue while preserving the rest of the breast. Radiation therapy follows to reduce the chance of recurrence. The safety of this approach depends on maintaining a favorable ratio between the size of the tumor and the size of the breast, and on confirming that surgical margins are free of cancer cells.
Mastectomy (removal of the entire breast) becomes necessary when the cancer is multifocal, meaning it appears in more than one area of the breast, or when the tumor is large relative to the breast. Sentinel lymph node biopsy, where a few lymph nodes near the breast are checked for cancer spread, is part of the surgical plan when invasive cancer is present.
Beyond surgery, additional treatment depends on the characteristics of the underlying cancer. Because HER2 is overexpressed in the vast majority of cases, HER2-targeted therapy is commonly part of the treatment plan. Hormone therapy may also play a role: roughly 40% of cases test positive for estrogen receptors and about 30% for progesterone receptors, making those tumors responsive to hormone-blocking drugs. Chemotherapy is considered based on the stage and biology of the underlying cancer, just as it would be for any breast cancer.
Prognosis and What Affects It
Outcomes for Paget’s disease of the breast depend heavily on what’s happening beneath the nipple. When the disease is confined to the nipple skin or associated only with non-invasive cancer (DCIS), the prognosis is generally favorable, with high long-term survival rates similar to other early-stage breast cancers.
When invasive cancer is present, the prognosis aligns with the stage of that cancer. The 60% of patients who have invasive disease at diagnosis face a more complex treatment path and a prognosis that reflects the size of the tumor, lymph node involvement, and molecular subtype. Early detection makes a meaningful difference, which is why persistent nipple changes that don’t respond to standard skin care deserve prompt investigation rather than a wait-and-see approach.