Intraductal Papilloma of the Breast: Prevalence of Malignancy and Natural History Under Active Surveillance.

BACKGROUND The optimal management of intraductal papillomas (IPs) without atypia diagnosed on needle core biopsy (NCB) is unclear. This study analyzed the malignancy risk of immediately excised IPs and characterized the behavior of IPs under active surveillance (AS). METHODS We retrospectively reviewed the pathology and imaging records of patients diagnosed with IPs without atypia on NCB during a 10-year period (1999-2019). The malignancy upgrade rate was assessed in patients who had an immediate surgical excision, and the rates of both radiographic progression and development of malignancy were assessed in a cohort of patients undergoing AS. RESULTS The inclusion criteria were met in 152 patients with 175 IPs with a mean age of 51 ± 13 years. The average size of the IPs on initial imaging was 8 ± 4 mm. Most of the lesions (57%, n = 99) were immediately excised, whereas 76 (43%) underwent AS with interval imaging with a median follow-up period of 15 months (range, 5-111 months). Among the immediately excised IPs, surgical pathology revealed benign findings in 97% (n = 96) and ductal carcinoma in situ in 3% (n = 3). In the AS cohort, 72% (n = 55) of the IPs remained stable, and 25% (n = 19) resolved or decreased in size. At 2 years, 4% had increased in size on imaging and were subsequently excised, with ductal carcinoma in situ (DCIS, n = 1) and benign pathology (n = 1) noted on final pathology. CONCLUSIONS In a large series of breast IPs without atypia, no invasive carcinoma was observed after immediate excision, and 96% of the lesions had not progressed on AS. This suggests that patients with IP shown on NCB can safely undergo AS, with surgery reserved for radiographic lesion progression.