Breast Mass in Pregnancy
Karen Y. Oh, MD
DIFFERENTIAL DIAGNOSIS
Common
Normal Fibroglandular Tissue
Fibroadenoma
Simple Cyst
Complicated Cyst
Less Common
Breast Cancer
Lactating Adenoma
Abscess
Phyllodes Tumor
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Start with breast ultrasound for palpable lumps in pregnancy
Differentiate whether cystic or solid
Simple vs. complicated cyst (both benign)
Complicated cyst could be galactocele
Solid mass requires more careful evaluation
If benign-appearing, may follow in a young patient, though even benign lesions may grow in pregnancy
If suspicious do not hesitate to perform mammogram and ultrasound-guided core biopsy
If ultrasound negative, clinical follow-up warranted to assess for any changes
Helpful Clues for Common Diagnoses
Normal Fibroglandular Tissue
Slightly more echogenic parenchyma
Usually very dense on mammographic imaging due to hormonal stimulation of tissue and milk production
Fibroadenoma
Most common breast mass across all age groups
Peak age of occurrence → 20-30 years old
Can significantly enlarge during pregnancy
Many involute postpartum or after menopause
Circumscribed homogeneous mass growing parallel to breast tissues
“Wider than tall”
Isoechoic or slightly hypoechoic to fat
Variable effect on acoustic transmission
May have posterior acoustic shadowing, no effect, or increased posterior enhancement
If involuted fibroadenoma, may see echogenic, internal coarse “popcorn” calcifications
Atypical fibroadenomas may also have irregular or microlobulated margins
Should be sampled at any age if appears atypical
Simple Cyst
Presents as painful palpable mass, often with acute onset
Anechoic circumscribed mass
Smooth wall without irregularities or solid components
Increased through transmission
May have thin nonvascular septa
Complicated Cyst
Low-level internal echoes
Proteinaceous debris, cellular debris, or cholesterol crystals
Movement often visible with realtime imaging
Consider galactocele (cyst filled with milk) if during lactation
Can have fluid-debris level
Color or power Doppler ultrasound can show active swirling of debris
Benign finding; not an indication for removal or biopsy unless patient symptomatic and desires aspiration
Aspiration may require 18-gauge needle as fluid can be tenacious
Helpful Clues for Less Common Diagnoses
Breast Cancer
˜ 3% of breast cancers occur during pregnancy or lactation
Cancers are considered pregnancy-associated if occurs during pregnancy or within 1 year of delivery
Palpable hypoechoic, irregular mass; no specific appearance in pregnancy
May have posterior acoustic shadowing and echogenic halo
Do not hesitate to biopsy if lesion suspicious
Breast cancer can occur at any age
Late diagnosis common when found during pregnancy
Could be due to difficult breast exam, age of patient, rapid growth in setting of many physiologic changes
Treatment should be initiated despite pregnancy
Including surgery and chemotherapy
No significant known risk to the fetus in the 2nd-3rd trimester
Radiation therapy usually deferred
Most report similar outcome to patients with breast cancer diagnosed outside of pregnancy
If compare patients with similar age and stage at diagnosis
Some studies suggest prognosis worse during pregnancy if advanced stage at diagnosis
If chemotherapy given, can cause premature menopause
Lactating Adenoma
Not sonographically distinguishable from fibroadenoma
Abundant proliferative changes on histology, without atypia
Pregnancy-associated changes with secretory activity
Occurs during pregnancy and lactation
More commonly occurs during pregnancy than lactation
Abscess
Correlate with clinical history of infection
Usually erythematous/edematous overlying skin
Focal, complicated fluid collection on ultrasound
Can have irregular margins and echogenic halo of surrounding inflammation
May be difficult to distinguish from neoplasm unless correlated with clinical history
Ultrasound-guided drainage indicated to aid in resolution of infection
May require multiple aspirations during course of treatment until resolution
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