Do all mucocele-like lesions of the breast require surgery?

Mucocele-like lesions of the breast - A radiological and clinicopathological analysis

INTRODUCTION

Mucocele-like lesions (MLL) of the breast are rare entities which are considered to harbor uncertain malignant potential. Current UK guidelines recommend vacuum assisted excision (VAE) of all such lesions regardless of whether they display epithelial atypia. This study sought to review the key histological and radiological features of MLLs and compare their differing outcomes based on the presence of epithelial atypia.

METHODS

Pathology records of a single breast cancer screening center were retrospectively searched for all biopsy diagnosed MLLs over an 11-year period. Upgrade rates to malignancy (positive predictive values) were calculated by reviewing histology from the initial core biopsy and comparing with the corresponding excision specimen. Radiological images were simultaneously reviewed to provide radiological-pathological correlation.

RESULTS

Three of 11 patients (27.3%) with atypical MLLs on biopsy had malignant outcomes at excision, compared with only 1 of 36 patients (2.8%) with non-atypical MLLs. The majority of MLLs (93%) were identified as microcalcifications on mammographic imaging. No specific radiological features were predictive of malignancy.

CONCLUSIONS

Our data suggest that MLLs without atypia are potentially overtreated with current protocols and could be managed conservatively with radiological follow up. Radiological-pathological correlation is essential.

A review of mucinous lesions of the breast

Mucinous lesions of the breast include a variety of benign and malignant epithelial processes that display intracytoplasmic or extracellular mucin, including mucocele-like lesions, mucinous carcinoma, solid papillary carcinoma, and other rare subtypes of mucin-producing carcinoma. The finding of free-floating or stromal mucin accumulations is a diagnostic challenge of which the significance depends on the clinical, radiologic, and pathologic context. This article emphasizes the differential diagnosis between benign and malignant mucin-producing lesions, with a brief consideration of potential mimics, such as biphasic and mesenchymal lesions with associated with mucinous, myxoid, or matrix material.

Unusual Changing Calcification Patterns on the Mammogram in a Pure Mucocele-Like Lesion of the Breast: A Case Report

Patient: Female, 39

Final Diagnosis: Mucocele-like lesion

Symptoms: None

Medication: —

Clinical Procedure: —

Specialty: Radiology

Mucocelelike Lesions in the Breast: Radiologic and Clinicopathologic Correlations With Upgrade Rate

OBJECTIVE

The purpose of this article is to investigate the radiologic and clinicopathologic findings of mucocelelike lesions (MLLs) and the rate of pathologic upgrade with factors predicting it.

MATERIALS AND METHODS

We reviewed our institution's database from January 2006 to December 2012 and enrolled 89 women with 89 MLLs. The pathologic findings from the initial biopsies identified 71 lesions without and 18 lesions with associated high-risk lesions. Images were reviewed according to the BI-RADS lexicon. Clinical and pathologic results were analyzed statistically, and upgrade rates were calculated.

RESULTS

Of the 89 lesions, 67 (75.3%) underwent surgical excision and 22 (24.7%) did not. After surgical excision (n = 67), one lesion was upgraded to mucinous carcinoma, three were upgraded to ductal carcinoma in situ, and 16 were upgraded to MLLs with associated high-risk lesions (29.9% total upgrade rate; 20/67). A statistically significant higher percentage of MLLs with associated high-risk lesions was observed in the surgical excision group (94.4% vs 70.4%; p = 0.036). The final pathologic diagnosis revealed larger lesions (16.4 ± 9.1 vs 12.6 ± 6.8 mm; p = 0.024) and younger patients in the high-risk group (46.9 ± 7.7 vs 50.6 ± 9.1 years; p = 0.049). Although no significant differences were observed in the imaging findings, including the BI-RADS category, upgraded lesions were seen as a mass with calcification as a predominant feature.

CONCLUSION

This study revealed no significant differences in imaging findings or BI-RADS category between high-risk and non-high-risk breast MLLs. However, we confirmed that high-risk lesions typically are seen as larger masses with calcifications.

An Update of Mucinous Lesions of the Breast

Mucinous lesions of the breast include a variety of benign and malignant epithelial processes that display intracytoplasmic or extracellular mucin, including mucocelelike lesions, mucinous carcinoma, solid papillary carcinoma, and other rare subtypes of mucin-producing carcinoma. The most important diagnostic challenge is the finding of free-floating or stromal mucin accumulations for which the significance depends on the clinical, radiologic, and pathologic context. This article emphasizes the differential diagnosis between mucocelelike lesions and mucinous carcinoma, with a brief consideration of potential mimics, such as biphasic and mesenchymal lesions with myxoid stroma ("stromal mucin") and foreign material.

Mucocele-Like Lesions of the Breast: Rate of Upstaging and Cancer Development

BACKGROUND

Breast mucocele-like lesions (MLLs) are rare breast lesions. There is a paucity of literature on the rate of pathologic upstaging of MLL to in situ or invasive breast cancer. We sought to review our experience with MLL at a tertiary care center and review published literature.

METHODS

A retrospective review was undertaken of all patients with breast MLL at the Mayo Clinic, Rochester, from 1998 to 2016. Descriptive statistics were performed.

RESULTS

Overall, 30 patients were diagnosed with MLL, with a mean age of 54.6 years (range 51-58). Calcifications on screening mammogram were the most common method of MLL detection (n = 26, 86.7 %), with core needle biopsy (CNB) being performed in 29/30 patients. MLL with atypia was identified in 14 patients (48 %), and surgical excision was performed in 26 patients. Disease was upstaged to invasive disease in one patient (3.8 %) who presented with a palpable mass. With a median duration of follow up of 3.5 years [interquartile range 1-7.1], two patients developed contralateral invasive breast cancer (both patients had a remote history of invasive breast cancer on that side), and one patient developed contralateral in situ disease. Review of the literature demonstrates a 2.9 % upgrade rate of MLL without atypia on excisional biopsy.

CONCLUSIONS

The upstage rate of MLL identified on CNB to invasive disease at surgical excision in this series was 3.8 %. In cases with MLL presenting as calcifications, no cases were upstaged in this series. Across the literature, upstage rates of MLL without atypia on CNB are low, indicating excisional biopsy may be avoided in these cases.

The significance of extracellular mucin in breast fine needle aspiration specimens

OBJECTIVE

To determine if all breast fine needle aspiration (FNA) specimens with abundant extracellular mucin require excisional biopsy.

METHODS

Fifty cases of breast FNA containing extracellular mucin, reported with a recommendation for biopsy and with histological follow-up were reviewed. Cellular features were noted, and the cases reclassified ignoring the presence of mucin and then correlated with histological outcome.

RESULTS

Subsequent histology showed benign changes in 20% (10/50), two cases (4%) of atypical ductal hyperplasia (ADH) and 76% (38/50) to be malignant lesions, including three cases of ductal carcinoma in situ (DCIS). When the FNA cases were reviewed disregarding the presence of mucin, 11 cases were reclassified as benign and one case that contained mucin-like material but no epithelial cells reviewed as non-diagnostic. All cases of invasive mixed and mucinous carcinoma (MC) would have been reported with a recommendation for histological examination. In addition, the three cases each of fibroadenoma (FA) and a benign mucocoele-like lesion (MLL) were correctly identified as benign. However, two cases each of DCIS and ADH would have been reported benign with no recommendation for further histology.

CONCLUSIONS

Breast FNA specimens with mucinous material may arise from sampling of a range of benign and malignant processes; however, a biopsy should be recommended, even in cases of low cellularity, owing to sampling problems and the frequent co-occurrence of significant lesions. FNA is highly accurate at predicting carcinoma with mucinous differentiation although it is not possible to reliably predict if the lesion represents pure MC or a mixed carcinoma.

A pure mucocele-like lesion of the breast diagnosed on ultrasonography-guided core-needle biopsy: is imaging follow-up sufficient?

Purpose:

To evaluate the upgrade rate of ultrasonography (US)-guided core-needle biopsy (CNB) of the breast for a pure mucocele-like lesion (MLL), to evaluate the clinical and radiologic features, and to correlate the image-pathologic features further on to guide the management of MLL.

Methods:

Between January 2003 and February 2013, 14-gauge US-guided CNB was performed in 18,111 cases. Thirty-two cases associated with MLL were identified, and five cases of MLLs associated with breast carcinoma or with other high-risk breast lesions (i.e., atypical ductal hyperplasia [ADH], papillary lesions, lobular carcinoma in situ, and radial scar complex) were excluded. Among these 27 pure MLLs, 21 cases with surgical or vacuum-assisted excision (VAE) pathology were included in our study. Medical records, mammograms, and ultrasonograms were reviewed for the clinical and radiologic features of the cases.

Results:

Among the 21 cases with pure MLLs at CNB, the final pathology showed a 0% proportion of cases upgraded to malignancy. All the 21 cases with either surgical or VAE pathology were benign MLLs including three cases of focal involvement of ADH (14.3%). The common features were mammographic features of microcalcifications that were round in shape and had a grouped distribution. The US features included oval shape, circumscribed margin, parallel orientation, complex solid and cystic echo pattern, no posterior feature, and complex solid and cystic echoic masses. The predominant Breast Imaging Reporting and Data System (BIRADS) category was 4A. All the lesions showed image-pathologic concordance.

Conclusion:

For pure MLL on US-guided CNB with image-pathologic concordance, close imaging follow-up might be considered instead of surgical excision.

Focal extravasated mucin in breast core needle biopsies: is surgical excision always necessary?

Focal extravasated mucin (EM) with benign or atypical epithelium is a rare finding at breast core needle biopsy (CNB) and usually prompts surgical excision to rule out mucin-producing carcinoma. In the largest detailed series to date, we assessed surgical outcomes in lesions yielding EM with atypical or nonatypical epithelium at CNB. With IRB approval, we retrospectively reviewed 28 consecutive atypical and nonatypical CNBs with EM that underwent surgical excision at our center over a 22-year period. CNB imaging and pathologic findings were concordant if pathology sufficiently explained the radiologic features of the lesions. Pathologic findings in CNB and excision specimens were correlated. Statistical analysis was performed. CNBs sampled mammographic calcifications in 25/28 (89%) women and a mass in 3/28 (11%). All cases had concordant pathologic and imaging findings. At CNB, the epithelium associated with EM was atypical in 18/28 (64%) lesions and nonatypical in 10 (36%). Cancer (one mucinous carcinoma; three ductal carcinoma in situ) was present in 4/28 excision specimens (14%; 95% confidence intervals [CI], 4%-33%). All carcinomas were in lesions with epithelial atypia at CNB (4/18; 22%; 95% CI, 6%-48%) versus none (0/10; 0%; 95% CI, 0%-31%) in nonatypical lesions at CNB; this difference was not statistically significant (p = 0.3). Surgery is warranted for lesions yielding EM with atypia at CNB due to the high (22%) prevalence of cancer. Our data suggest that surgical excision of lesions yielding EM without epithelial atypia at CNB may not be necessary provided that imaging and pathologic findings are concordant.

Mucocele-like lesions diagnosed on breast core biopsy: assessment of upgrade rate and need for surgical excision

Mucocele-like lesion (MLL) is a rare mucinous lesion of the breast with highly variable upgrade rates to atypia or malignancy on excision. This spectrum of data has led to differing opinions on the need for surgical excision. We evaluated 50 core biopsy specimens diagnosed as having MLLs and correlated the findings with those of excision pathology. Thirty-eight patients underwent surgical excision and 29 were benign (76%), 4 had atypical ductal hyperplasia (11%), and 5 had ductal carcinoma in situ (13%), with an overall upgrade rate of 13%. However, the risk of upgrade was exclusively associated with the presence of atypia as seen on the needle core biopsy. All 22 MLLs without atypia had benign excisions, while 5 (31%) of the 16 patients with MLLs with atypia were upgraded to ductal carcinoma in situ on excision. No invasive carcinoma was identified. We believe it is reasonable that women with the core biopsy diagnosis of MLL without atypia and no associated mass be offered close clinical follow-up as an alternative to surgery.