Benign proliferative breast disease (ECR 2017 Case of the Day)

Clinical History

39-year-old asymptomatic woman. Newly appeared asymmetric density in the right axillary tail on mammographic images, without palpable or ultrasound abnormality. Lesion visible on MRI could not be found on second look ultrasound.

Imaging Findings

Newly appeared asymmetric density in the right axillary tail on mammography without ultrasound abnormality. Irregular-shaped lesion with indistinct margins presenting type II time intensity curve on MRI could not be found on second look ultrasound.

Discussion

A. Background: benign proliferative breast disease may mimic malignancy on imaging.
B. Clinical Perspective: Usual lobular hyperplasia may be asymptomatic or may occur as a palpable lump. It has been observed also in lactating women. Sclerosing lobular hyperplasia may be associated with fibroadenomatoid hyperplasia. [1, 2]
C. Imaging Perspective: Newly appeared asymmetric density on mammography was considered BI-RADS 4. As it was not palpable, not seen in ultrasound, MRI was proposed. Irregular shape, type II time intensity curve raised the suspicion of malignancy. The lesion was not found by second look ultrasound and MR-guided biopsy was difficult to perform because of the posterior position of the abnormality.
D. Outcome: Mammography-guided preoperative wire localisation and excision was performed. Post-operative histology revealed usual lobular hyperplasia. Because of the benign histology, short-term follow-up or adjuvant therapy was not necessary. As preoperative sampling could not be performed, surgical excision was able to provide histological results.
E. Take-Home Message, Teaching Points:
- Benign proliferative disease may mimic malignancy on imaging.
- Newly appeared asymmetric density on mammography and irregular nodular enhancement with type II time intensity curve on MRI are suspicious of malignancy.
- Even nodular lesions are not always found by second look ultrasound
- If imaging-guided sampling cannot be performed, imaging-guided localisation and excision may provide histological diagnosis.

Differential Diagnosis List

Final Diagnosis

Benign proliferative breast disease (usual lobular hyperplasia)

URL:	https://eurorad.org/case/15206
DOI:	10.1594/EURORAD/CASE.15206
ISSN:	1563-4086