2/2 fluid accumulation in the TDLU bc of distention/obstruction of the efferent ductule

Features: 

• Can be solitary or multiple

• Can cause sx: palpable mass and/or pain

• Influenced by hormonal fluctuations

  • Can be seen in pre-, peri-, and postmenopausal women

  • Cyclical

US: must have all 4 features (PAIN!)

• Imperceptible wall

• Anechoic

• No internal vascularity

• Posterior enhancement

  • Small cysts (<5-8 mm) and/or deep cysts (>3 cm deep to skin) may not show posterior enhancement 2/2 US attenuation. 

  • If mass cannot be confidentially characterized as a cyst, an aspiration attempt may be needed to confirm. If aspiration does not confirm simple fluid, then the procedure should be converted to a core bx. 

MR: round T2 hyperintense mass with smooth margins and no assoc enhancement

Cyst may fluctuate in size and sx over time based on hormonal changes

Demo:

• More common in premenopausal women and those using estrogen therapy. 

• 38% of postmenopausal women not on estrogen were found to have cysts at some point during the 3 years of screening US (ACRIN 6666 protocol)

• Found in 37.5% of all women (MC in 35-50 yo)

New, enlarging, &/or palpable circumscribed masses on mammo merit further evaluation by US

US aspiration is necessary only when there is diagnostic uncertainty or for symptomatic relief.

• Fluid is sent for cytology only when bloody.

2/2 fluid accumulation in the TDLU bc of distention and obstruction of the efferent ductule

Solitary or multiple

Sx: can cause pain and palpable mass

CM is considered benign or probably benign in perimenopausal women.

US: 2-3 mm cysts w/ thin (0.5 mm) intervening septations.

Perform bx if...

• Finding is new or enlarging in a postmenopausal woman NOT on HRT to exclude a malignancy such as...

  • Apocrine or papillary ductal carcinoma in situ 

  • Mucinous carcinoma

• There is a discrete solid component or suspicious calcifications

2 MCC of clustered microcysts are fibrocystic changes and apocrine metaplasia (aka apocrine cysts)

• Apocrine metaplasia is diagnosed when there are dilated acini in the lobular portion of the TDLE lined with columnar epithelium containing eosinophilic cytoplasm. The columnar epithelial cells secrete fluid resulting in dilation of the acini and eventually cysts that are seen on imaging. A histopathologic dx of AM is benign and requires no further evaluation if the pathology is concordant with imaging.

• Fibrocystic changes

If CC has thick inspissated secretions they can be difficult to distinguish from solid masses.

Features:

• Imperceptible wall

• Non internal vascularity

• +/- posterior enhancement

• Homogeneous low-level internal echoes /debris

  • Tends to be dependent

BIRADS

• 2 - if multiple

  • When mass shows circumscribed margins, homogeneous low-level echoes, posterior enhancement, and is incidentally found on sono in pt with multiple cysts -> classify it as probably benign or benign

• 3 - 6 mo FU

• 4 - aspiration if needed to resolve new mammo finding or solid vs complicated cyst to avoid FU

Get aspiration and possible bx if...

• Margins are not circumscribed

• Mass is new, palpable, or tender 

Special types of complicated cysts:

• Hemorrhagic cyst

• Galactocele

Characteristics of a complex cystic and solid mass include at least 1 or combo of the following:

• Thick wall > 0.5 mm or mural nodularity

• Thick septations >0,5 mm

• Intracystic mass

• Mixed cystic and solid mass or mostly solid w/ cystic areas 

Additional findings:

• +/- internal vascularity

• Posterior enhancement

DDx is broad

Suspicous for malignancy (BR 4B) w/ 23-36% of such masses proving to be malignant