Paget’s disease of the breast is a rare form of breast cancer that primarily affects the nipple and the dark skin around it, known as the areola. This condition is distinct from Paget’s disease of the bone, which is unrelated.
Understanding Paget’s Disease of the Breast
Paget’s disease of the breast is almost always associated with an underlying breast cancer within the milk ducts. In the majority of cases, it is found alongside either non-invasive ductal carcinoma in situ (DCIS) or invasive breast cancer. The widely accepted theory explains that specialized cancer cells, known as Paget cells, originate from a tumor deeper within the breast and migrate through the milk ducts to the skin surface of the nipple and areola.
While less common, another theory suggests that Paget cells might originate independently in the nipple itself. Regardless of origin, the presence of these cells on the nipple surface indicates a connection to a cancerous process within the breast.
Factors Influencing Progression Speed
The perceived speed at which Paget’s disease of the breast progresses is primarily determined by the nature of any underlying breast cancer. If the underlying condition is only ductal carcinoma in situ (DCIS), a non-invasive form, the progression of the surface skin changes might be slow, and the cancer itself is confined to the milk ducts. However, if an invasive breast cancer is present beneath the nipple, the overall progression rate is dictated by that invasive cancer, which has the potential for growth and spread beyond the ducts.
The specific type and characteristics of the underlying cancer influence its growth rate, with invasive forms generally progressing more rapidly than DCIS and having potential for spread. Factors such as the tumor’s grade (how aggressive the cancer cells appear), hormone receptor (estrogen/progesterone), and HER2 status play a role in determining the underlying cancer’s behavior and potential for spread. High-grade DCIS, for instance, carries a greater risk of progressing to invasive disease.
A significant factor that can make the disease appear to progress quickly upon diagnosis is a delay in identifying the condition. The initial symptoms of Paget’s disease are often mistaken for benign skin conditions, such as eczema or dermatitis. This common misdiagnosis can lead to several months of delayed treatment, allowing any underlying cancer more time to develop and potentially advance before a correct diagnosis is made.
Clinical Presentation and Diagnosis Timeline
Paget’s disease of the breast typically presents with changes to the nipple and areola. Common symptoms include:
- Redness
- Flaking
- Scaly skin
- Itching
- Crusting
- Oozing
- Burning sensations
- A nipple that appears flattened or inverted
- Discharge from the nipple, which can be straw-colored or bloody
Because these symptoms frequently resemble benign skin conditions like eczema or dermatitis, the disease is often misdiagnosed. This can lead to delays in diagnosis, with symptoms sometimes present for several months before correct identification.
The diagnostic process typically involves a thorough physical examination, followed by imaging tests such as a mammogram, ultrasound, and sometimes an MRI to assess the breast for underlying tumors. A biopsy of the nipple or areola is the definitive method to confirm Paget’s disease by identifying the characteristic Paget cells. This comprehensive evaluation helps determine the full extent of the disease and guides treatment decisions.
Prognosis and Outlook
The overall outlook for individuals with Paget’s disease of the breast is primarily determined by the stage and characteristics of the underlying breast cancer, rather than by the Paget’s manifestation itself. The presence of Paget cells on the nipple does not change the staging of any underlying cancer. Treatment strategies are therefore guided by the deeper tumor.
If the underlying condition is limited to ductal carcinoma in situ (DCIS), meaning the cancer cells have not spread beyond the milk ducts, the prognosis is generally favorable with appropriate treatment. For cases associated with DCIS, the 5-year survival rate can be very high, around 97.5%.
When invasive breast cancer is present, the prognosis depends on factors such as the tumor’s size, whether it has spread to nearby lymph nodes, and its specific biological features. For individuals with invasive ductal carcinoma associated with Paget’s disease, the 5-year survival rate is approximately 84.1%. Early and accurate diagnosis, followed by comprehensive treatment, including surgery, radiation, and potentially chemotherapy or targeted therapy, plays a significant role in managing the disease and improving outcomes.