To investigate the clinical misdiagnosis causes and diagnostic features of nipple adenoma (NA) with atypical ultrasonographic manifestations.

The clinical data of a NA patient admitted to the Department of General Surgery, the First Affiliated Hospital of Wannan Medical College on July 17, 2020 were analyzed, and the literatures were reviewed.

The 29-year-old female patient underwent " left nipple mass resection" for left nipple mass 2 months ago. Postoperative pathology showed left nipple papillomatosis, and the patient was admitted to the hospital due to repeated incision. Physical examination revealed skin rupture of the left nipple with no obvious exudation, and showed no enlarged lymph nodes in bilateral armpits. Ultrasound examination showed that the left nipple was enlarged with rich blood flow signal, and Paget′s disease of the breast was considered. The postoperative pathological diagnosis was NA. Microscopically, the tumor was a glandular structure, located in the dermis, with papillary or adenomatous hyperplasia of ductal epithelium. Immunohistochemically, in tumor cells, low molecular cytokeratin (CAM 5.2) in glandular epithelium, p63 in myoepithelium, basal cytokeratin 5/6 (CK 5/6) in hyperplastic epithelium, smooth muscle actin (SMA) in myoepithelium and Ki-67 in nuclear were positive, but human epidermal growth factor receptor 2 (HER-2) and tumor suppressor gene (p53) were negative.

NA is easily misdiagnosed as nipple papillomatosis and Paget′s disease of the breast. Ultrasound examination is a helpful method for the assessment of NA. However in some cases, it is pretty difficult to make a correct diagnosis of NA just by ultrasound examination, pathological examination and immunohistochemistry should be used to confirm the diagnosis.