A galactocele is a milk-filled cyst composed of cuboidal or flat epithelium which frequently occur in women who are lactating or pregnant. A women concerned about a strange 'smooth and moveable' lump or breast discomfort will typically bring the condition to the attention of her doctor, who will likely refer the patient for breast cancer screening, just to be sure. Galactoceles can mimick fibroadenomas as well as breast carcinomas, but they are always non-cancerous and do not increase risk of breast cancer in any way. Galactoceles can be caused by anything that blocks a breast duct during lactation. It is possible that breast carcinoma has caused a change and blockage of some kind, but far more likely that it is the result of routine, benign causes. Galactoceles are the most common benign breast lesions in lactating women. They do seem to occur more frequently, however, after breast-feeding has stopped; as milk is retained and becomes 'stagnant' within the breast ducts.
Differential diagnosis for galactoceles and not breast cancer
Given that breast cancer tends to effect older, post menopausal women, the clinical presentation of a moveable lump in a younger lactating woman is a pretty good indication for the likelihood of a galactocele, or possibly lactating adenoma. But the patient will typically be sent for ultrasound imaging and a fine needle aspiration biopsy just to be sure. The presence of milk aspirated from the mass ( and not clear fluids or blood ) will generally confirm the diagonsis and rule out carcinoma and fibroadenoma. Aspirated milk tends to be 'thicker' when the lesion is older and the sample is obtained after breast feeding has stopped.
Galatoceles contain milk
Galactoceles are similar to ordinary cysts (see above.) But instead of clear fluid, they contain milk. Galactoceles are not dangerous, though they can be uncomfortable. Treatment involves a physician draining (aspirating) the galactocele with a fine needle.
Radiological appearane of galactoceles depends on the amount of fat content
Mammograms (X-rays) are generally not performed on pregnant women. For this reason, it is most likely that the breast lesion will be evaluated by ultrasound. (although needle biopsy will likely be the first investigation ) The mammographic appearance of a galactocele will depend upon the amount of fat in the fluid ( milk secretions tend to be fatty). In addition to the fat content, the mammographic appearance of galactocele will also depends on the density and viscosity of the fluid, and the amount of proteinaceous material present. Fat-fluids will tend to be radiolucent (transparent) on the X-ray, and appear darker. This could however mimic the appearance of lipoma, and ones looks for additional diagnositc criteria. But in general they will appear as an oval circumscribed mass whose radiolucency indicates a high fat content. However, mammographically a mass such as this will in virtually indistinguishable from a true lipoma.
On ultrasound, galactoceles may appear in a variety of ways, some of which are similar in appearance to solid masses, including some breast cancers. But generally speaking, galactoceles appear on a sonogram as small, round hypoechoic nodules. Usually they have well-defined margins with thin, echogenic walls, but on occasions they present with indistinct or microlobulated margins. Additionaly, there is often mild posterior shadowing (distal acoustic enhancement).
Other histological apsects of galactocele breast lesions
Galactoceles are frequently accompanied by necrotic debris or inflammatory fluids. Histological evaluation often reveals a large variety in the proportions of fate, lactose, and proteins in the fluid mixture. The presence of inflammation in the cysts is generally due to leakage. Thicker tumor walls also tend to be associated with inflammation.
Subcateogories/descriptions of Galactoceles
Galactoceles are sometimes broken into descriptive categories, depending upon the fat content and subsequent 'radiolucency' of the mass. The variable amounts of fat versus water content, and also the relative 'freshness' of the milk secretions change the texture and consistency and appearence of the tumor.
Psuedolipoma is the name given to the galactocele tumor when the fat content is very high and appears as a completely radiolucent mass.
galactocele as a 'cystic mass with flat fluid level'
A galactocele might be described as a cystic mass with a 'flat fluid level. This implies that the proportions of water and fat are variable, but the 'milk' content is fresh. The combination fo the low viscosity (ability to blend) of the milk with the lower density of the fat elements can allows it to rise above the water content, which is 'heavier'. It is interesting, but one can only see this situation if the mammogram is undertaken while the patient is in an upright posture.
Pseudohamartoma and 'complicated cyst-like' galactoceles
When the milk is older, which no longer allows for the physical separation of milk and water content, the situation is usually described as a pseudohamartomo. In this case the fluid is thicker and 'stickier' (more consistent). When a galactocele begins to evolve into this 'pseudo-solid' state, it begins more and more to resemble a potential breast cancer tumor.( But the well-defined shape and distinct margins would only suggest a benign tumor). Mammogram and ultrasound features of the psuedohamartoma will also look quite alot like a hamartoma or possibly a complicated cyst.
Treatment of Galactoceles
Galactoceles are not serious or dangerous, but they may be uncomfortable. As with many cysts, the typical treatment for a galactocele is to leave them alone. When the hormonal change associated with pregancy and lactation cease, the condition should resolve on its own. But, in cases of true discomfort, attempts may be made to 'drain' the galactocele through fine needle aspiration. In fact, the diagnostic aspiration of fluid from they cyst may prove to be theraputic at the same time.
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Copyright Steven B. Halls, MD Last edited 25-August-2011