A 34-year-old woman noticed a small lump in the center of her left nipple and watched it slowly grow for two years. A mammogram flagged it for closer evaluation. When surgeons removed it, pathologists found not one benign growth but two, including one that neither of her imaging tests had shown.
The case, published in May in the Journal of Surgical Case Reports by surgeons at Corewell Health in Dearborn, Michigan, and Mercy Health in Perrysburg, Ohio, describes a nipple adenoma occurring together with an intraductal papilloma. The authors call the combination extremely rare, with very limited published literature.
The report is a reminder that nipple lesions can look worrisome yet prove benign, and that imaging alone does not always tell the whole story.
A Growing Lump and an Uncertain Mammogram
The woman found the lesion during a self-exam. It was flesh-colored, centered on the nipple, and measured 1.1 centimeters. Doctors saw no enlarged lymph nodes, skin dimpling, or other skin changes.
A diagnostic mammogram showed asymmetric prominence of the left nipple and was classified as BI-RADS 4A, a category indicating low suspicion for cancer that typically prompts further evaluation. An ultrasound then showed a 9-millimeter complex fluid collection within the nipple that appeared benign.
Wanting a definitive answer, and citing cosmetic concerns, she chose to have the lesion surgically removed under intravenous sedation.
Two Diagnoses in One Specimen
Pathology showed a nipple duct adenoma plus an intraductal papilloma with florid ductal hyperplasia and focal atypia, meaning some cells looked abnormal under the microscope. There was no evidence of cancer. She recovered well, with a satisfactory cosmetic result.
The second finding was the surprise. Neither the mammogram nor the ultrasound showed evidence of an intraductal papilloma, and she did not have bloody nipple discharge, which the authors describe as the most characteristic symptom of that condition.
That, the authors argue, reinforces the value of surgical excision, both to confirm a suspected diagnosis and to rule out other underlying disease. If patients prefer less invasive approaches, they write, the possibility of hidden disease should be discussed in detail so the patient can make an informed decision.
A Rare Tumor Known for Mimicking Cancer
Nipple adenoma is a benign growth arising from the milk ducts. According to the report, it makes up less than 1% of diagnosed benign breast lesions and is most common in women in their 30s. It is often described as a well-defined, crusting erosion of the nipple that can mimic breast cancer, eczema, or Paget's disease, a form of cancer involving the nipple.
Imaging often does not settle the question. A radiology-pathology review in the Journal of Breast Imaging notes that nipple adenomas are often invisible on mammograms, while ultrasound can show a mass with increased blood flow centered in the nipple. Diagnosis is usually made with a punch biopsy or excision. The same review notes that cancer can be found elsewhere in the same or opposite breast, though published experience with such cases is small.
Similar diagnostic puzzles appear across the literature. In a case report in Frontiers in Oncology, another 34-year-old woman had persistent bloody discharge and nipple erosion that mimicked cancer before surgery confirmed a benign nipple adenoma.
Treatment usually means removing the growth. A report in the International Breastfeeding Journal on managing nipple adenomas during pregnancy notes that complete surgical excision is the main treatment, while alternatives such as Mohs micrographic surgery, nipple-splitting enucleation, and cryotherapy can be considered.
Intraductal papilloma is more common, representing an estimated 2% to 3% of benign breast tumors, according to the new report. It is usually diagnosed with a core needle biopsy that checks for atypia.
Benign Usually, but Not Always Alone
For most patients, the outlook with nipple adenoma is good. A pathology study of 50 cases in the American Journal of Surgical Pathology found no recurrences among the 44 patients with follow-up over a median of 66 months, concluded that simple excision is curative, and reported that no definitive link to invasive cancer has been established.
Still, the growths sometimes occur alongside other disease. A systematic review of 387 cases from 86 studies found that 10.34% of patients had a co-diagnosis of a malignant or premalignant condition. Over a mean follow-up of about 57 months, 2.87% had a recurrence and 1.79% developed cancer, notably among those with co-diagnoses. Higher co-diagnosis rates were linked to older age.
Reported ages vary widely. The review found a mean age of 44, while the 50-case pathology study reported a median age of 56. The review's authors advocate a comprehensive evaluation of every case, with excision as the primary treatment, and suggest Mohs surgery can be advantageous when nipple adenoma is the only diagnosis.
A single case report cannot estimate how often nipple adenomas and papillomas occur together. But the Michigan and Ohio surgeons conclude that a complete workup is essential, even when a benign diagnosis is expected, so that no underlying condition is missed.
Anyone who notices a new or growing nipple lump, crusting, erosion, or discharge should have it evaluated promptly by a clinician, since these changes can have both benign and cancerous causes.
Key Questions Answered
What is a nipple adenoma?
It is a rare, benign growth of the milk ducts in the nipple that can resemble breast cancer, eczema, or Paget's disease.
What did surgery reveal in this case?
Pathology showed a nipple adenoma plus an intraductal papilloma with focal atypia, and no cancer.
Why was the second finding surprising?
Neither the mammogram nor the ultrasound showed the papilloma, and the patient had no bloody nipple discharge.
Can nipple adenomas become cancer?
A 50-case study found no definitive link to invasive cancer, but a systematic review found that about 10% of cases had a co-occurring malignant or premalignant diagnosis.
What should people do if they notice nipple changes?
New lumps, crusting, erosion, or discharge should be checked promptly by a clinician.
