Nipple-Originating Solid Papillary Carcinoma In Situ: A Case Report and Literature Review.

Solid papillary carcinoma of the breast is a rare histopathological subtype of papillary neoplasms, and its in situ variant localized to the nipple is particularly uncommon. Current oncology literature provides limited evidence on standardized diagnostic criteria, biological behavior, and optimal treatment strategies for this entity. We describe a 73-year-old Chinese woman with a two-year history of a left nipple mass that developed erythema and ulceration five days prior to presentation. Imaging studies (ultrasonography and MRI) identified an isolated nipple lesion (BI-RADS 4b) with no other breast tissue involvement. Wide local excision confirmed solid papillary carcinoma in situ (pTisN0M0), with pathological evaluation showing R0 resection margins. The patient received standard adjuvant endocrine therapy (letrozole 2.5 mg/day) and showed no evidence of recurrence at 9 month follow-up. For patients with nipple-confined solid papillary carcinoma lacking high-risk features, complete surgical excision constitutes the mainstay of treatment, complemented by postoperative adjuvant endocrine therapy to mitigate recurrence risk.