Rare imaging appearance of adenoid cystic carcinoma of the breast: A case report

Adenoid Cystic Carcinoma of the Breast: Multimodality Imaging Findings and Review of the Literature

RATIONALE AND OBJECTIVES

Adenoid cystic carcinoma (ACC) of the breast is a rare type of breast cancer with favorable prognosis. There is limited data on the radiological findings of this rare tumor in literature. The aim of this study is to determine the most common imaging features and review the literature.

MATERIALS AND METHODS

Pathological databases of seven institutions from 2009 to 2021 were retrospectively reviewed, and patients with a diagnosis of ACC of the breast were determined. Thirteen patients whose imaging studies could be recalled from the picture archiving systems (PACS) were included in the study. Clinical and pathological findings as well as follow-up data were recorded. Radiological findings were analyzed and categorized based on BI-RADS 5th edition.

RESULTS

There were 16 mass lesions in 13 patients (two multifocal cases, one case with recurrence). Mammography demonstrated 14 masses, while ultrasound (US) demonstrated all. MRI was available in only seven cases, with eight masses. The most common findings were round or oval shape on all modalities (78.57%-93.75%). Other frequent findings were parallel orientation (81.25%), isoechoic or hyperechoic echogenicity (62.5%), high T2 signal (87.5%), restricted diffusion (71.43%), and homogeneous enhancement (62.5%). Mammography, US and MRI showed circumscribed margins resembling a benign lesion in 35.71%, 37.5% and 50% of the lesions respectively. Three patients had a cyst-like echogenicty on US. Half of the lesions were avascular on Doppler US (6/12) and half were soft (2/4) on strain elastography. Although there were benign features on all imaging modalities seperately, all lesions could be categorized as BI-RADS 4 or 5 when the findings were combined. However 9/16 masses were BI-RADS 4A, emphasizing the subtlety of the malignant features.

CONCLUSION

ACC of the breast can present with findings resembling a benign lesion on different imaging modalities. Although combination of all imaging findings correctly indicated the suspicious nature of the lesions in all cases, final classification was BI-RADS 4A in most of them. Radiologists should be aware of the more frequent findings of ACC of the breast for early diagnosis. US findings of isoechoic or hyperechoic appearance, and cyst-like echogenicity have not been reported previously in literature.

Triple-Negative Breast Cancer Histological Subtypes with a Favourable Prognosis

Simple Summary

Breast cancers that lack expression of the predictive markers oestrogen receptor, progesterone receptor and human epidermal growth factor receptor-2 are known as triple-negative breast cancers (TNBCs) and are generally considered to have a poor prognosis. As available targeted treatments are not effective, aggressive chemotherapy is frequently advocated for patients with TNBC. It is now becoming apparent that TNBC is not one entity but constitutes a range of malignancies with different clinical behaviour. This paper reviews 7 distinct histological subtypes of TNBC where the overall prognosis is favourable, and aggressive systemic treatment is generally not indicated. Their recognition and separation from the larger group of no special type TNBC are important. The members of the European Working Group for Breast Screening Pathology review the morphology, known molecular features and reported outcomes, and formulate a consensus statement regarding the approach to the subtypes that are associated with a favourable prognosis.

Abstract

Triple-negative breast cancers (TNBC), as a group of tumours, have a worse prognosis than stage-matched non-TNBC and lack the benefits of routinely available targeted therapy. However, TNBC is a heterogeneous group of neoplasms, which includes some special type carcinomas with a relatively indolent course. This review on behalf of the European Working Group for Breast Screening Pathology reviews the literature on the special histological types of BC that are reported to have a triple negative phenotype and indolent behaviour. These include adenoid cystic carcinoma of classical type, low-grade adenosquamous carcinoma, fibromatosis-like metaplastic carcinoma, low-grade mucoepidermoid carcinoma, secretory carcinoma, acinic cell carcinoma, and tall cell carcinoma with reversed polarity. The pathological and known molecular features as well as clinical data including treatment and prognosis of these special TNBC subtypes are summarised and it is concluded that many patients with these rare TNBC pure subtypes are unlikely to benefit from systemic chemotherapy. A consensus statement of the working group relating to the multidisciplinary approach and treatment of these rare tumour types concludes the review.

Breast adenoid cystic carcinoma arising in microglandular adenosis: A case report and review of literature

BACKGROUND

Breast adenoid cystic carcinoma (AdCC) is a rare invasive carcinoma composed of epithelial and myoepithelial cells. Microglandular adenosis (MGA) is a rare benign proliferative lesion consisting of small, uniform, and round glands formed by a single layer of epithelial cells and basement membrane without a myoepithelial cell layer. MGA may progress to atypical MGA and carcinoma arising in MGA. Among various invasive carcinomas from MGA, AdCC has been rarely reported. Here, we report a case of AdCC arising in MGA.

CASE SUMMARY

A 59-year-old woman was diagnosed with a newly developed density on a routine mammogram. The density was similar to or slightly lower than that of the breast parenchyma. Sonography showed an irregular mass with a slightly higher echo than that of fat. Magnetic resonance imaging showed an irregular mass with a similar T1 signal intensity and a slightly higher T2 signal intensity compared to muscles or the breast parenchyma. The lesion showed heterogeneous internal enhancement with an initially slow and delayed persistent enhancing pattern. Microscopically, the tumor was composed of invasive AdCC, in situ AdCC, and MGA. AdCC is composed of basaloid and ductal epithelial cells forming cribriform or solid sheets, or haphazardly scattered small cribriform or tubular glands. MGA showed small glands with a single epithelial lining and retained lumen. S-100 staining was strongly positive in MGA area. The patient underwent breast-conserving surgery with sentinel lymph node biopsy.

CONCLUSION

Breast AdCC arising in MGA showed unique imaging findings that was different from usual invasive cancer.

Adenoid cystic carcinoma of the breast - Discordant size on imaging and pathology: A case report and review of literature

Introduction

Adenoid cystic carcinoma (ACC) is an uncommon tumour of the breast. It is known for its rare lymph node involvement and distant metastasis. A triple-negative breast cancer that has a favorable prognosis compared to other triple negative ductal carcinomas, it accounts for approximately 0.1-1% of all breast cancers.

Presentation of case

We report a case of a 69-year-old female with a palpable left breast mass who underwent multiple imaging modalities with significant size variance between the studies. Breast conserving therapy (BCT) was performed with axillary sentinel lymph node biopsy (SLNB) followed by radiation therapy (RT). Pathological examination confirmed the tumour as ACC.

Discussion

ACC, known as an persistent if low-grade malignant tumour of salivary gland, is considered to have low-malignant potential in the breast. It is a very rare subtype and from this scant data, there is minimal mention about size discrepancy between imaging modalities such as ultrasound and MRI.No consistent MRI features have been demonstrated, with the exception of T2 hyperintensity in larger lesions and T2 iso-intensity in smaller lesions. Ultrasound demonstrates primarily a hypoechoic or heterogenous mass with minimum vascularity, consistent with our radiographic findings.

Conclusion

ACC is a rare entity in breast cancer pathology. Its size can be highly variable as measured by various radiographic modalities, and final Pathology from the surgical specimen is, as always, required for an accurate tumoral diameter. With that caveat, careful utilization of pre-operative imaging modalities is critical in pre-surgical planning to choose the appropriate surgery.