An intraductal papilloma is a common, non-cancerous growth that forms inside a milk duct of the breast. The term “intraductal” indicates its location within the breast duct system. This finding is relatively frequent, particularly in women between the ages of 35 and 55. Although the discovery of any breast abnormality can cause concern, this specific condition is classified as benign.
Understanding Intraductal Papillomas
An intraductal papilloma is a small, wart-like tumor composed of glandular tissue, fibrous tissue, and blood vessels. These components form a stalk-like structure known as a fibrovascular core, which projects into the open space of the milk duct. The growth is covered in epithelial cells, the same type of cells that line the ducts.
These growths typically measure between one and two centimeters in diameter, limited by the size of the milk duct where they reside. The papilloma’s presence can partially or completely obstruct the duct, leading to a buildup of fluid or other material behind the blockage. The condition results from an abnormal overgrowth of the epithelial cells that line the milk ducts, though the exact biological trigger is not yet fully understood.
Presentation and Symptoms
In many instances, an intraductal papilloma is asymptomatic and is discovered incidentally during routine breast imaging, such as a mammogram or ultrasound. When symptoms appear, they are usually related to the papilloma’s location within the ductal system. The most common sign is a spontaneous nipple discharge, which may be clear, sticky, or bloody.
The discharge occurs because the papilloma is a fragile structure with many tiny blood vessels. Trauma or friction within the duct can cause these vessels to bleed into the ductal fluid. This discharge is often limited to a single duct in one breast, a characteristic feature that helps differentiate it from other causes of nipple discharge.
The papilloma may occasionally be felt as a small lump, especially if located in a larger duct close to the nipple. These palpable lumps are often found directly behind or near the areola, and may sometimes be accompanied by localized pain or discomfort.
Classifications and Cancer Risk
Intraductal papillomas are categorized into two primary types based on their number and location within the ductal system, which has implications for the long-term risk of developing breast cancer. Solitary papillomas, also called central papillomas, are single growths that occur in the larger milk ducts close to the nipple. These lesions are nearly always benign and do not carry a significantly increased lifetime risk for breast cancer unless other abnormal cell changes are present.
Multiple papillomas, sometimes referred to as papillomatosis, develop in the smaller, more peripheral ducts deeper within the breast tissue. This type is associated with a slightly higher, though still low, long-term risk of breast cancer.
The elevated risk with multiple papillomas is often due to an association with atypical hyperplasia, an overgrowth of abnormal but not yet cancerous cells within the ducts. Therefore, a definitive diagnosis through a tissue sample is necessary to determine the presence of these atypical cells, which dictates the management plan.
Diagnosis and Treatment
The initial step in diagnosing an intraductal papilloma involves imaging, typically a mammogram and a targeted ultrasound, which can reveal a mass or ductal widening. A ductogram, using contrast dye injected into the affected duct, may also be used to visualize the lesion. However, imaging alone cannot definitively distinguish a benign papilloma from a cancerous growth.
A definitive diagnosis requires a tissue sample obtained through a needle biopsy, such as a core biopsy or a vacuum-assisted excision (VAE). This procedure removes a small portion or the entire lesion for examination under a microscope to confirm its benign nature and check for atypical cells.
Treatment decisions are based on symptoms, the number of papillomas, and the presence of atypical cells. Symptomatic papillomas or those containing atypical cells are typically removed surgically through a procedure like an excisional biopsy or a microdochectomy, which removes the affected duct. Asymptomatic, solitary papillomas confirmed as benign by a needle biopsy may be managed with active surveillance, involving periodic clinical exams and imaging.