A case of adenosis and mastitis association: can those two benign lesions behave as DCIS?

Clinical History

Microglandular adenosis is a benign breast entity considered as a variant form of adenosis. It plays an important role in mimicking Ductal Carcinoma In Situ. We report a case of a woman with a
suspicious finding at breast imaging. The histologic features revealed an area of microglandular adenosis.

Imaging Findings

The 36-year-old woman underwent her first mammogram without any clinical findings except for pain in the right breast. A mammogram was performed using standard projections with a digital technique (Fig. 1). We found an asymmetric radio-opacity, in the upper outer quadrant of the right breast. Because of breast density and findings of the mammogram, the woman underwent an ultrasound examination which showed a hypoecoic mass, with a radial shape and irregular margins. At color-power-Doppler the mass revealed partial vascularisation, with a small vessel within the lesion. According to these suspicious findings, we decided to perform an MR study. MRI of the breast was performed using FFE-T1 and TSE-T2 weighted sequences, along the axial plane followed by the dynamic contrast-enhanced protocol. The dynamic series consisted of a three-dimensional FFE-T1 weighted sequence, with a total of 6 dynamic scan. MR depicted a pseudonodular area with spiculated and irregular margins. The enhancement of the lesion was homogeneous but the time-signal intensity curve presented an initial uptake, after which enhancement was abruptly cut off, and the signal intensity showed a plateau in the intermediate and late postcontrast periods (type II). A fine-needle aspiration was performed. The report reads as follows: “epithelial cells, hyperplasia and cystis. Follow up of the lesion is recommended”. Definitive hystologic diagnosis was fibrocystic disease with sclerosing, blunt duct and microglandular adenosis.

Discussion

According to Fischer et al, adenosis has nonspecific characteristics to traditional and MR Imaging. While the excellent sensitivity of breast MR imaging proves particularly advantageous for its application in the preoperative patient, its limited specificity continues to be problematic, particularly in patients referred for clarification of a conventionally inconclusive finding [2]. Two different approaches are known in distinguishing benign and malignant lesions: a meticolous analysis of the lesion’s structure and internal architecture supported by high spatial resolution, and different enhancement kinetics supported by dynamic protocols. Mastitis generally manifests as a distinct, firm to hard mass that may involve any part of the breast but tends to spare the subareolar regions. The features of the mammogram are variable, ranging from normal findings in patients with dense breasts to masses with benign or malignant features and focal asymmetric density, the most frequently described abnormality. The US appearance of multiple clustered, often contiguous hypoechoic tubular lesions is sometimes associated with a large, hypoechoic mass and has been considered suggestive of the disease, although the latter feature is not always found [3]. MRI shows a heterogeneous enhancement, prognosis is good, although local recurrence has been reported.
Primary treatment consists of excisional biopsy [4]. During our management of this partially asymptomatic patient (only referred pain to right breast) nothing showed up that would cause us to suspect an inflammation; starting with conventional imaging (all findings suspicious for carcinoma) up to MRI, our purpose was to exclude the possibility of a malignant lesion, with reference to literature: be aware of DCIS in differential diagnosis of benign sclerosing and microglandular adenosis.
Through our experience, we assumed a connection to sclerosing adenosis and mastitis, which could behave as a malignant lesion. The response to such lesions should be, apart from imaging in order to make a diagnosis, the histologic test to determine whether conservative surgery is necessary.

Differential Diagnosis List

Final Diagnosis

Fibrocystic disease with sclerosing, blunt duct and microglandular adenosis.

URL:	https://www.eurorad.org/case/5815
DOI:	10.1594/EURORAD/CASE.5815
ISSN:	1563-4086