Galactocoeles occur exclusively in lactating or post-weaning women as a milk-filled cystic lesion which is well-circumscribed, fluid-density lesion on ultrasound, often associated with breastfeeding.
Description
A galactocele is a benign breast lesion that typically occurs in lactating or post-weaning women, consisting of a milk-filled cyst. It results from the obstruction of a lactiferous duct, leading to the accumulation of milk and formation of a cyst. Galactoceles are the most common benign lesion found in lactating women and usually resolve spontaneously.
Pathogenesis
The development of a galactocele is thought to be related to obstruction of a lactiferous duct, which may occur due to inflammation, trauma, or an anatomical anomaly. The obstruction leads to milk accumulation, resulting in cyst formation. The milk within the cyst may become inspissated over time, leading to the characteristic appearance on imaging studies.
Epidemiology, Risk Factors & Associations
- Almost exclusively affects lactating or recently weaned women. Most occur on cessation of lactation.
- No specific risk factors have been identified, but improper breastfeeding techniques or trauma may contribute to their formation.
Clinical Features
- Typically presents as a smooth, mobile, painless mass within the breast.
- Some women may experience mild discomfort or fullness in the affected area.
- Usually unilateral, but can occur in both breasts.
Complications
- Infection or abscess formation, although rare, can occur.
- Large galactoceles can cause cosmetic deformity or discomfort.
Pathological Features
Histopathology
- Macroscopic: A cyst containing milky fluid or semi-solid material.
- Microscopic: Lined by a thin layer of epithelium, with the cyst content showing fat globules and proteinaceous material.
Serology
- Non-specific; not applicable for diagnosis.
Biochemistry
- Aspirate shows a variety of proportions of proteins, fat, and lactose
Radiological Features
General Features
- US is the most useful modality
- Slight predilection for sub-areolar region
US
- B-Mode: Well-defined, anechoic or hypoechoic lesion with possible internal septations and fluid-fluid or fat-fluid level. The content may appear echogenic if the milk has become inspissated.
- Doppler: No internal vascularity. Minimal peripheral vascularity.
MG
- Mammography is less commonly performed in lactating women due to the increased breast density.
- May show a well-circumscribed, round, or oval radiolucent lesion (due to high-fat content, possibly mimicking lipoma or harmartoma)
- Fat-fluid level within the cyst may be demonstrated on mediolateral view
Differential Diagnosis
- Breast abscess: Typically presents with signs of infection, including pain, redness, and fever (less common). May have similar appearance.
- Fibroadenoma: A solid, circumscribed ovoid/almond shaped benign breast tumour that is common in younger, non-lactating women. Classically demonstrates homogenous echogenicity with posterior acoustic enhancement. Lactating adenomas have a similar appearance, sometimes demonstrating colour flow.
- Invasive Carcinoma: Presence of a solid component with vascularity would be concerning.
Management
- Conservative management is often sufficient, with spontaneous resolution expected.
- Needle aspiration may be performed for symptomatic relief or to confirm the diagnosis.
- Surgical intervention is rarely required, reserved for cases complicated by infection or persistent discomfort.