Low-grade adenosquamous carcinoma of the breast: a review with focus on imaging and management

Abstract

Low-grade adenosquamous carcinoma is a less frequent variant of metaplastic breast carcinoma, incidentally detected during screening and has an age distribution similar to other breast carcinomas. It shares characteristics with both benign and malignant carcinomas: its mammographic and sonographic features are therefore nonspecific. Breast conserving surgery with adjuvant radiation therapy is currently the preferred therapeutic approach. The aim of this review is to describe the imaging and clinical features of low-grade adenosquamous carcinoma for appropriate identification and diagnosis. The associated pitfalls, histopathologic and epidemiologic factors, natural course, and management of low-grade adenosquamous carcinoma are also discussed.

Keywords: Low-grade adenosquamous carcinoma; breast cancer; metaplastic carcinoma.

Figure 1.

(a) DBT slice shows a focal asymmetry in the left upper-outer quadrant of a 54-year-old patient. (b) A subsequent additional targeted view is performed to study better the radiological features, confirming the focal asymmetry with fine linear microcalcifications. (c) On the following US, there is a hypoechoic mass with microlobulated margins of about 1.7 cm.

Figure 2.

(a) 2D projections mammography shows – only in mediolateral oblique projection – an architectural distortion with a diameter of about 12 mm in the right upper-inner quadrant of a 46-year-old woman. (b) On US, there is a hypoechoic mass with indistinct margins, of uncertain nature. ((c) and (d)) We proceed to DBT vacuum-assisted breast biopsy which allowed us to diagnose LGASC.

Figure 3.

((a) and (b)) Mammograms of a young woman with extremely dense breasts. There are no mammographic findings either in craniocaudal or mediolateral oblique projections. (c) On the other hand, on US, a suspicious mass appears in the left lower peri-areolar area.

Figure 4.

((a) to (c)) In craniocaudal and mediolateral oblique projections of a 70-year-old woman, suspicious microcalcifications (black arrow) in the left external periareolar area are identified. (d) This finding corresponds in US scans, obtained with high-frequency probe, to a suspicious mass not circumscribed complex cystic/solid hypoechoic with microcalcifications associated.