Breast cyst: Clinical sciences

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Introduction0:00–0:50

Breast cysts are fluid filled masses that develop within the glandular tissue of the breast, usually in the upper outer quadrant; but they can appear anywhere in the breast.
Overall, breast cysts are the most common cause of breast symptoms, and they typically arise in patients assigned female at birth between the ages of 35 and 50 years, usually because of an overproduction of estrogen and suppression of progesterone.
Fortunately, most breast cysts are benign; but new cysts in older postmenopausal patients pose a higher risk of underlying malignancy, and this risk increases if they are currently on hormone replacement therapy.Alright, now, when a patient presents with a chief concern suggesting a breast cyst, the first step is to obtain a focused history and perform a physical examination.

History and Physical0:50–1:47

The most commonly reported symptom is a breast lump and possibly localized pain that worsens just prior to menstruation each month.
However, some patients can be asymptomatic, and a breast lump can be discovered as part of a physical examination performed for another reason.Speaking of which, physical examination findings that suggest a breast cyst include a palpable, solitary, smooth and firm breast mass that is freely mobile.
Occasionally, the mass can also be tender on palpation. With these findings, you can suspect a breast cyst.

Ultrasound1:47–3:58

The next step is to order a breast ultrasound to confirm your diagnosis. If there are no findings on the ultrasound that would indicate a breast cyst, then you should consider an alternative diagnosis.
On the other hand, if a breast cyst is identified, ultrasound findings can help classify it as either a simple, complicated or a complex cyst.
Here’s a clinical pearl! Breast findings on imaging can be categorized with a standardized system called BI-RADS, which stands for Breast Imaging-Reporting and Data System.
BI-RADS is typically used for mammography findings, but it can be applied for ultrasound as well. So, with BI-RADS, the imaging findings are assigned into categories labeled as 0 to 6.
First, 0 means incomplete, which needs additional imaging or comparison with previous images if available. Next, 1 is negative, meaning that imaging is normal, with no findings like masses or calcification; while 2 indicates findings are completely benign, meaning that mammography reveals findings with no probability of malignancy; a category of 0, 1, and 2 can only be used when undergoing routine screening.
On the other hand, 3 is probably benign, meaning that mammography may reveal a finding with minimal malignant potential of less than 2%, so these patients should get follow-up imaging.
Next, 4 is suspicious for malignancy, meaning that mammography may reveal a finding with malignant potential between 2 to 94%, where biopsy will likely be indicated.
Then, a category of 5 is highly suspicious of malignancy, with malignant potential over 95%. Lastly, 6 is known malignancy that has been proven with biopsy, and requires definitive management with surgery, chemotherapy, or radiation.Now, let’s take a look at some ultrasound findings that suggest the presence of a simple breast cyst.

Simple Cyst3:58–6:25

The ultrasound might show an oval or round lesion that is well-circumscribed with posterior acoustic enhancement but without any internal echoes or solid components.
The lesion can also have visible thin walls and septa that are less than 0.5 mm thick. If just these findings are present, you are dealing with a simple breast cyst, which is classified as BI-RADS 2, or benign.
Of note, there’s no increased risk of breast cancer detected in a mass that fulfills the ultrasound diagnostic criteria of a simple cyst.Alright, let’s talk about treatment.
If your patient is asymptomatic, no intervention is necessary, and you can simply continue with routine breast cancer screening.
On the other hand, if your patient experiences symptoms like pain and discomfort, then the next step is an ultrasound-guided aspiration.
If there is a complete collapse of the cyst after aspiration, no further interventions are needed, so you can continue with routine breast cancer screening.
However, if the cyst doesn’t collapse completely or there is blood in the aspirate, your next step is to perform an ultrasound-guided core needle biopsy.Okay, if the histopathology shows benign features only, such as epithelial hyperplasia and ductal dilation, your patient can return for a clinical breast exam in addition to a breast ultrasound and mammogram every 6 to 12 months for the next 1 to 2 years, in order to look for 2 year stability.
If there are no changes or new findings during that time, your patient can continue their routine annual screenings. On the flip side, if the histopathology shows malignant features, such as a high mitotic index, cellular atypia, nuclear changes and extracellular invasion, an excisional biopsy needs to be performed to remove the cyst.
Okay, now, let’s back up to discuss another set of ultrasound findings. Once again, you might see an oval or round lesion, with thin walls, and septa that are less than 0.5mm thick.

Complicated Cyst6:25–8:18

The lesion could have posterior acoustic enhancement, as well as low-level internal echoes that may change shape when the patient changes positions during the ultrasound; but it doesn’t have any solid components within the cyst.
If you see these features on ultrasound, you are dealing with a complicated breast cyst, which can be classified as a BI-RADS 2 or 3.
This means that the lesion is either benign or probably benign. For BI-RADS 2 and 3 complicated cysts, you can repeat the clinical breast exam and breast ultrasound in about 6 months.
If there are no changes in the size of the cyst and no solid components are seen on the ultrasound, repeat another clinical breast exam, as well as an ultrasound and mammogram in another 6 months.
On the other hand, if the cyst has increased in size or if solid components are now present, your next step is to perform an ultrasound-guided core needle biopsy.
If the histopathology is benign, your patient can return for a clinical breast exam, an ultrasound, and a mammogram every 6 to 12 months for the next 1 to 2 years.
If there are no changes or new findings during that time, they can proceed with routine annual screenings. However, if the histopathology confirms malignancy, then an excisional biopsy is needed to remove the cyst.Alright, now that we’ve reviewed complicated cysts, let’s discuss the last set of characteristics you might see on the breast ultrasound.

Complex Cyst8:18–10:56

Ultrasound might reveal a lesion with lobulated, indistinct, or irregular margins with or without posterior acoustic enhancements.
You might see solid components with thick walls and septa that are greater than 0.5 mm in thickness. If you see these characteristics, you can make your diagnosis of a complex breast cyst, which is classified either as a BI-RADS 4 or 5 lesion.
BI-RADS 4 indicates the lesion is suspicious for malignancy, while BI-RADS 5 is highly suggestive of malignancy. Here’s a clinical pearl!
Based on ultrasound findings, complex cysts can also be classified under one of four categories, with the probability of malignancy increasing with each one.
Type I masses have a wall and septa thicker than 0.5mm. Type II masses have solid components on the wall of the cyst.
Finally, type III and IV masses have mixed cystic and solid components, but the difference is that type III masses are predominantly cystic, while type IV masses are predominantly solid, and have cystic inclusions.
Now, after making your diagnosis of a complex cyst, you need to get an ultrasound-guided core needle biopsy to determine if it’s benign or malignant.
Benign histopathological diagnoses include fibrocystic changes and fibrocystic mastopathy; intraductal papilloma; phyllodes tumor; as well as an abscess, hematoma or fat necrosis in the breast.
In this case, the patient can return for a clinical breast exam, an ultrasound, and a mammogram every 6 to 12 months for the next 1 to 2 years.
If there are no changes or new findings during that time, they can return to their routine annual screenings. On the other hand, if atypia or malignant findings are present, like atypical ductal hyperplasia, ductal carcinoma in situ, and infiltrating ductal carcinoma, an excisional biopsy is required.

Review10:56–12:05

Alright, as a quick recap… Breast cysts are fluid-filled masses typically found in patients between the ages of 35 and 50, and are typically benign.
Breast cysts should be evaluated with ultrasound to determine if they’re simple, complicated, or complex. Simple cysts require ultrasound-guided aspiration only if symptomatic.
If the cyst doesn’t collapse fully or has a bloody aspirate, an ultrasound guided biopsy can be performed to assess for malignancy.
Complicated cysts warrant ultrasound-guided biopsy if they increase in size or have solid components. Finally, complex cysts always require ultrasound-guided core needle biopsy.
Finally, regardless of the cyst type, if the histopathology shows benign findings, your patient can return for a clinical breast exam in addition to a breast ultrasound and mammogram every 6 to 12 months for the next 1 to 2 years.
On the other hand, if there are malignant findings,