Galactoceles, also known as lactoceles, are the most common benign breast lesion typically occurring in young lactating women; however, they mostly develop following the cessation of lactation ¹. 

Clinical presentation

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.

Complications

Secondary infection with development of a breast abscess.

Pathology

A galactocele is 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.

Location

There may be predilection towards the subareolar region.

Radiographic features

Mammography

The mammographic appearance of galactoceles varies depending on the fat and protein content and the consistency of the fluid. Based on these, galactoceles may present as:

• 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

Ultrasound appearances vary widely. Sonographic characteristics according to one study were as follows ³:

• cystic/multicystic: ~50%

• mixed (cystic + solid): ~37%

• solid: ~13%

Color Doppler interrogation in general shows a lack of blood flow.

In uncertain cases, an aspiration is recommended which will usually yield milky fluid ¹⁰.

Treatment and prognosis

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

History and etymology

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

Differential diagnosis

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