[citation needed] Signs of duct ectasia can include nipple retraction, inversion, pain,[5] and various intermittent couloring discharge (ranging from white, to green/black, to grey).

[6] The duct widening is commonly believed to be a result of secretory stasis, including stagnant colostrum, which also causes periductal inflammation and fibrosis.

Duct widening with associated periductal fibrosis is frequently included in the wastebasket definition of fibrocystic disease.

In plasma cell rich lesions diagnosed on core biopsies, steroid-responsive IgG4-related mastitis can be identified by IgG/IgG4 immunostaining.

In some contexts, it was used to describe a particular form of nonpuerperal mastitis coincident with fibrocystic disease, frequently involving pasty (coloured) nipple discharge, nipple retraction, retroareolar abscess and blue dome cysts.

In addition to nonspecific duct widening the myoepithelial cell layer is atrophic, missing or replaced by fibrous tissue.

Because research literature regarding duct ectasia is anything but abundant it is probably easiest to determine the exact meaning(s) intended by the respective authors on a case-by-case basis and this section can offer only a few hints.