Squamous Cell Carcinoma In Situ (SCCIS) of the Nipple Following Breast Conserving Therapy: Case Report

Squamous cell carcinoma in situ (SCCIS), also known as Bowen's disease, is a precancerous intradermal lesion that commonly arises in sun-exposed areas. Other risk factors include radiation, inflammation, carcinogen exposure, and human papilloma virus exposure. Its presentation on the nipple-areolar complex is extremely rare with 14 cases reported in literature. We report a case of a postmenopausal woman with remote history of breast cancer and DCIS treated with bilateral breast conserving surgery followed by adjuvant radiation. She developed SCCIS of the right nipple nearly 30 years later. Associated symptoms included bloody nipple discharge, nipple rash, and nipple pruritus for 1.5 years. A punch biopsy of the right nipple lesion identified epithelioid cells in the intradermal space staining CK7 (+) and p40 (+)/p63 (+), classifying the lesion as Paget's disease. The patient elected to proceed with bilateral mastectomies without reconstruction. Final surgical pathology revealed radiation induced atypia and atypical keratinocytes that focally extend throughout the full epidermal thickness. Immunohistochemical staining demonstrated CK7 (-), CK5/6 (+), p40 (+), HER2 (-) and GCDFP15 (-) consistent with the diagnosis of SCCIS. Paget's disease of the nipple and SCCIS may present with similar clinical and histopathologic features; however, they are managed differently. Nipple lesions in the setting of prior radiation should raise concern for SCCIS. Clinicians should be aware of this rare, but potential sequelae in patients with a history of breast cancer treated with breast conserving therapy and nipple complaints.