Last revised by Angela Liao on 7 Jul 2023

Galactoceles, also referred to as lactoceles, are the most common benign breast lesion typically occurring in young lactating women; however, they mostly happen on cessation of lactation 1

Patients usually present with a painless breast lump occurring over weeks to months. The lesion can present as single or multiple nodules and can be unilateral or bilateral.

Secondary infection with development of a breast abscess.

It is essentially a retention cyst resulting from lactiferous duct occlusion. Diagnosis can be achieved with percutaneous aspiration 8. Biochemical analysis of material aspirated from galactoceles shows a variety of proportions of proteins, fat, and lactose. Macroscopically, the milk within the galactocele may appear white and of usual viscosity if fresh, or thickened if the liquid is older.

There may be predilection towards the sub-areolar region.

Mammographic appearance of galactocele can be varied depending on the fat and protein content and the consistency of the fluid. Based on these, the galactoceles could appear like:

  • pseudolipoma: due to significant fat content, the mass seems radiolucent

  • fat-fluid level within cyst: when fat and water are present, and the milk is in a fresh liquid state, a characteristic fat-fluid level is seen due to the viscosity difference. This can be demonstrated on mediolateral view with the beam horizontal to the upright patient

  • pseudohamartoma: seen when contents are old milk and water. Due to highly viscous old milk, significant separation of fat and water is not possible and hence gives a hamartoma-like appearance on the mammogram

Ultrasound appearances can be widely variable. Sonographic characteristics according to one study are as follows 3:

  • cystic/multicystic: ~50%

  • mixed (cystic + solid): ~37%

  • solid: ~13%

Color Doppler interrogation will show a lack of blood flow.

In uncertain cases, an aspiration is recommended in the first instance which will classically yield milky fluid 10.

They are benign lesions and spontaneous resolution occurs in a vast majority of cases. A small percentage have a residual collection that may mimic a fibroadenoma or complex cyst.

The term galactocele derives from the Greek words galatea meaning milky white and -cele (-coele) meaning pouch 9.

General considerations on imaging include:

  • lactating adenoma: seen as a solid lesion and may show color flow within it

  • breast abscess: has a different clinical presentation, but can develop as a complication

  • fibroadenoma: classically ovoid or almond-shaped with a smooth border, internal homogeneous echogenicity and acoustic enhancement 7

  • carcinoma of the breast: especially for certain lesions on ultrasound

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