Table 1 Differential diagnosis of GLM

GLM

Unknown etiology. Motivations are blunt breast trauma, lactation disorder, galactostasis, hyperprolactinemia, etc. [60]

Women who have delivered with breastfeeding history tend to develop GLM. Women who have not delivered seldom develop GLM

It frequently occurs on the periphery of the breast and concentrically involves the areola area. The subcutaneous abscess can spread to the whole breast, and can form recurrent ulcers or sinuses with a prolonged healing time

Ultrasonography often presents hypoechoic or uneven masses, with or without duct dilation

Non-caseating granulomas centered on the breast lobular, distributed multifocally, varying in size, with or without micro-abscesses

Ductal dilatation/periductal inflammation of the breast

Unknown etiology. Ductal dilatation may be associated with nipple deformities, blocked milk ducts, smoking, and bacterial infections [61]

Women in all age groups can develop ductal dilatation, more often in perimenopausal women. Women who have not been delivered can develop ductal dilatation as well

Manifestations include nipple discharge with nipple retraction. The lesion is centered on the areola [62], showing eccentric development. The large ducts behind the areola dilate, and an areola abscess may appear

Obvious duct dilation, fine light spots inside, and flow signs when pressurized can be observed by ultrasound. Dilated, tortuous, blocked and deformed duct can be observed by galactography

Breast duct is highly dilated, the wall of the duct is thickened or ruptured, and the cyst cavity is filled with pink granular thick material. Infiltration of lymphocytes, plasma cells and neutrophils can be seen around the dilated duct [63]

Zuska disease/subareolar abscess

Zuska may be associated with the breast duct obstruction, congenital malformation of breast duct, and nipple retraction

Zuska mainly occurs in non-lactating period, more common in women aged 14–66 years old, especially unmarried women

Swelling under the areola, swelling formation or abscess, lactiferous fistula and repeated attacks, prolonged non-healing are important characteristics of this disease

One or more hypoechoic or anechoic areas with blood flow signals can be detected around the areola by ultrasound

Squamous metaplasia of lactiferous tube columnar epithelium at the base of the nipple

Breast cancer

Breast cancer may be related with a family history of breast cancer, BRCA1/2 mutation [64], exposure of radiation, first menstruation before 12 years old, first pregnancy after 35 years old, no pregnancy, tobacco and alcohol, and psychological stress. Oncogenic and latent viruses such as HPV, CMV, EBV, MMTV and BLV are recently accused to be etiologic factors in the pathogenesis of breast cancer. Moreover, stress has a role in activation of these viral mechanisms

The incidence rate gradually rises after the age of 20, and more frequently in perimenopausal and post-menopausal women

Breast cancer usually presents a single mass with unclear borders, hard texture and poor mobility, and may be accompanied by enlarged ipsilateral axillary lymph nodes. As a rare subtype of breast cancer, inflammatory breast cancer develops rapidly, and local skin may show inflammation-like manifestations, including redness, edema, thickening, roughness, and increased surface temperature [65]

A hypoechoic mass with unclear borders and blood flow signals can be detected by Doppler ultrasound[66]. Ultrasound manifestations of inflammatory breast cancer include thickened skin and extensive parenchymal echo enhancement of the breast. Mammography shows an increased density of masses with irregularity margin or with Burr sign, small and dense calcification

–