Mucocele-like lesions of the breast: a clinical outcome and histologic analysis of 102 cases

Abstract

Mucocele-like lesions (MLL) of the breast are characterized by cystic architecture with stromal mucin and frequent atypia, but it is unknown whether they convey long term breast cancer risk. We evaluated 102MLL that were derived from a single institution benign breast disease (BBD) cohort of 13412 women who underwent biopsy from 1967–2001.MLL were histologically characterized by type of lining epithelium, architecture of the lesion, associated atypical hyperplasia (AH) and for incidence of breast cancer (14.8 years median follow-up). A relatively large proportion of MLL (42%) were diagnosed in women >55 years of age AH was significantly more frequent in MML patient compared to the cohort overall (27% vs 5%, p<0.001). Breast cancer has developed in 13 patients with MLL.. This frequency is only slightly higher than population expected rates overall (Standardized incidence ratio (SIR) 2.28, 95% CI 1.21–3.91), and not significantly different from women in the cohort with (non atypical) proliferative breast lesions. Younger women (<45) with MLL had a non-significant increase in risk of cancer compared to the general population (SIR 5.16, 95% CI 1.41–13.23). We conclude MLL is an uncommon breast lesion that is often associated with co-existing AH. However, in women over age 45, MLL do not convey additional risk of breast cancer beyond that associated with the presence of proliferative disease.

Mucocele-like lesions diagnosed on breast core biopsy: Low risk of upgrade and subsequent carcinoma

“…The clinical significance of non‐malignant breast lesions diagnosed on core biopsy is related to the risk of developing carcinoma in the future and the potential for upgrade to carcinoma on excision. Recent data from the Mayo Clinic Benign Breast Disease cohort indicates that patients with mucocele‐like lesions without atypia do not have an elevated risk for the future development of breast cancer . The primary issue in contemporary management is whether the risk of upgrade is sufficient to require all patients with mucocele‐like lesions on core biopsy to undergo immediate surgical excision.…”

“…The primary issue in contemporary management is whether the risk of upgrade is sufficient to require all patients with mucocele‐like lesions on core biopsy to undergo immediate surgical excision. The difficulty in distinguishing a mucocele‐like lesion from an invasive mucinous carcinoma in some cases leads to recommendations for complete excision of all mucocele‐like lesions . Additionally, some core biopsy series that combined mucocele‐like lesions with and without atypia into one category have shown upgrade rates as high as 30% .…”

“…indicates that patients with mucocele-like lesions without atypia do not have an elevated risk for the future development of breast cancer. 2 The primary issue in contemporary management is whether the risk of upgrade is sufficient to require all patients with mucocele-like lesions on core biopsy to undergo immediate surgical excision. The difficulty in distinguishing a mucocele-like lesion from an invasive mucinous carcinoma in some cases leads to recommendations for complete excision of all mucocele-like lesions.…”

“…Mucocele‐like lesions are relatively uncommon findings in breast biopsies . These lesions were first described by Rosen with the characteristic histologic findings of mucin‐filled cysts with extrusion of mucin into the adjacent stroma.…”

“…These lesions were first described by Rosen with the characteristic histologic findings of mucin‐filled cysts with extrusion of mucin into the adjacent stroma. In the long‐term follow‐up of mucocele‐like lesions in the Mayo Clinic Benign Breast Disease Cohort, an association with co‐existing atypical hyperplasia was noted but mucocele‐like lesions did appear to confer an increased risk for the subsequent development of breast cancer . In current practice, mucocele‐like lesions are often initially diagnosed on image‐guided core needle biopsies and most undergo immediate surgical excision to exclude the possibility of a limited sampling of an invasive mucinous carcinoma .…”