Non-puerperal mastitis masking pre-existing breast malignancy: importance of follow-up imaging

Abstract

Mastitis is an inflammatory condition of the breast with common symptoms of pain, swelling, erythema, warmth, and fever. Diagnosis of mastitis is easily made on the basis of typical symptoms and ultrasonographic findings, such as diffusely increased echogenicity of the parenchyma and subcutaneous fat, or skin thickening. However, when it occurs in women middle-aged or older, associated malignancy should be considered. In our cases, we detected irregular hypoechoic malignant masses after the disappearance of inflammatory changes. Therefore, when non-puerperal women have inflammatory signs on their breast, follow-up imaging should be performed. In particular, in the case of persistent or growing palpability after the recovery of breast inflammation, percutaneous core biopsy and short-term follow-up with ultrasonography should be considered to exclude the associated malignancy.

Keywords: Breast; Breast neoplasms; Diagnosis; Mastitis; Ultrasonography.

Fig. 1.. A 56-year-old woman with the symptoms of left mastitis.

A. Sonogram shows a diffusely increased echo in subcutaneous fat and parenchyma with skin thickening. The engorged edematous breast and diffuse hyperechogenicity disturb the distinction of each structure of the breast. There are multiple tubular hypoechoic lesions in the left outer breast (arrowheads). B. Sonogram taken 3 weeks later shows the disappearance of the edema and skin thickening. However, diffusely distributed irregular hypoechoic lesions are revealed in the left outer breast with internal echogenic spots from microcalcifications (arrowheads). C. Mammogram shows an irregular hyperdense mass with a segmental distribution of microcalcifications in the left outer breast (arrowheads). D. Axial maximum intensity projection image shows an extensive enhancing lesion in the left outer breast (arrowheads).

Fig. 2.. A 63-year-old woman with the symptoms of left mastitis.

A. Sonogram shows a diffusely increased echo of the left breast with mild skin thickening (arrow). Sonographic penetration is poor, and the distinction between retromammary fat and the parenchyma is not clear (arrowheads). B. Prominent duct distention is seen in the left subareola with some internal debris (arrow). C. Mammogram taken 10 days later shows diffuse and bizarre trabecular thickening of the left breast (arrowheads) and the left axillary lymphadenopathy (arrow). Skin thickening or haziness of the subcutaneous fat is not present. D. Multiple irregular hypoechoic masses are seen in the deep layer of the left breast (arrows). Previously increased echogenicity of the fat and skin thickening disappears. The distinction of subcutaneous fat and parenchyma is very clear. E. Subareolar duct distension is still seen, but internal debris and adjacent inflammatory changes are gone (arrow).