Ultrasound of non mass-like breast lesions
Topics discussed in this article:
- Normal breast anatomy by ultrasound:
- 1.Benign breast lesions:
- 2.Malignant breast lesions:
- 3. Post treatment changes:
Normal breast anatomy by ultrasound:
The breast on US can be classified into 3 zones:
- Premammary: which is composed of skin and subcutaneous tissue. Normal skin thickness by ultrasound doesn’t exceed 2 mm.
- Mammary: the fibrogalndular tissue, its composition varies from highly glandular beast seen in young age to total fatty breast seen in older age.
- Post mammary: mainly referred to the chest wall, its muscles and fat.
Not all breast changes are due to pathological causes, some changes may be physiological.
This is could be observed during pregnancy and lactation, due to the effect of circulating hormones; estrogen and progesterone, on breast tissue where on ultrasound the whole breast appears to be hypoechoic, inhomogenous with prominent ductal system and vascularity.
Many breast pathologies can present as diffuse lesions, which can be further classified into benign and malignant breast lesions.
1.Benign breast lesions:
a)Mastitis:
This is referred to inflammation of breast tissue, it most commonly occurs in the in lactating patient, or following lactation, yet it can occurs at any age.
There are different presentations to mastitis, which can be classified as follows:
1.Plasma cell mastitis:
Commonly referred to duct ectasia, the patient usually presents with dilated ducts >2mm, mainly located subareoral with no signs of inflammation or increase vascularity.
It may or not be associated with debris (inspissated secretions) in the ducts.
2.Acute mastitis :
This is due to infection of the breast tissue, usually caused by Staph Areus infection.
The patient will present with redness and induration. On ultrasound it may be a focal or diffuse area of hypoechic glands with hyperechoic fat lobules due to edema and increased vascularity.
It is important to diagnose mastitis early and treat it, before complicating into breast abscess, as this will spare the patient the need of any surgical drainage.
3.Granulomatous mastitis:
It is a rare form of mastitis that may be due to tuberculosis, sarcoidosis or any other non specific granulomatous disease.
Its appearance varies from focal decreased parenchymal echogenicity with acoustic shadowing and clusters of tubular hypoechoic lesions to mass-like appearance.
b)Gynecomastia:
Diffuse glandular pattern in male breast, may be unilateral or bilateral.
c)Early stage of fat necrosis:
It presents within few days after trauma, commonly seat belt injury, as asymmetric accentuated breast mastalgia.
On ultrasound it appears as diffusely increased echogenicity of the fat with diffuse edematous changes which may be easily missed except if compared to the contralateral normal side.
Histopathological examination is mostly mandatory to exclude diffuse malignant process.
d)Focal adenosis:
The patient is usually presented with localized pain, with no signs of inflammation, sometimes a mass can be felt.
On Ultrasound, we see condensation of glandular tissue element at focal area with no increase vascularity.
e)Breast edema:
Breast edema is not a pathology by itself, but it indicates the presence of an underlying pathology.
It may be present as a part of systemic edema in patients with organ failure (i.e heart failure), part of non specific breast signs in autimimmune diseases (i.e Rheumatoid arthrirtis, SLE) or secondary to another breast lesion as associated finding in case of mastitis, inflammatory carcinomatosis.
On ultrasound it appears in the form of skin thickening with increased thickness of the subcutaneous layer, having anechoic tubular images in the subdermal fat (dilated lymphatic channels) and parenchymal hypoechoicity.
f)Mondor disease :
It is due to superficial thrombophlebitis , leading to a focally painful (and often palpable) superficial vein that may be associated with overlying skin discoloration.
US shows a noncompressible “beaded” structure (thrombosed vein) with lack of internal color Doppler flow.
Usually it is radially oriented, and sometimes it is confused as inflamed dilated duct.
g)Pseudoangiomatous Stromal Hyperplasia (PASH):
It is a mesenchymal lesion composed of myofibroblasts, which sometimes includes glandular components. It is frequently seen as an incidental microscopic finding.
On ultrasound its apperance varies from solid masses to an ill-defined area of compact stromal hyperplasia with conglomerate cystic spaces.
a)Inflammatory carcinomatosis:
A type of locally advanced rapidly progressive breast cancer with dermal lymphatic permeation presenting clinically as inflammatory skin changes in the form of diffuse skin erythema, induration, peau d'orange appearance mildly or non responding to systemic antibiotics.
Sonographic picture is confusing being presented as skin thickening, diffuse breast edema, non localized tissue heterogeneity with increased vascularity.
Punch biopsy involving the dermal lymphatics is necessary before moving to the pre-operative chemotherapy regimen.
2)Pleomorphic lobular carcinoma:
A high grade infiltration lobular carcinoma which may be multicentric and bilateral.
It may be assymptomatic, clinically occult and suspected during routine breasts ultrasonography as segmental, regional or diffuse area of architectural distortion with or without faint pleomorphic calcifications, breasts asymmetry or "shrinking breast".
MRI with contrast may be needed before the implementation of the treatment plan to confirm the diagnosis and assess for multicentricity.
c)Lymphoma and leukemia:
Wide range of clinical and sonographic presentations with non specific sonographic picture in the form of diffuse skin thickening and tissue edema likely due to malignant lymphatic permeation.
3. Post treatment changes:
a)Myocutaneous flap reconstruction:
It is a process of autologous breast reconstruction after mastectomy in which transverse rectus abdominus myocutaneous flap (TRAM) is mostly used including the overlying fat and tissue as well as the muscle pedicle, alone or in combination with breast implant (mainly silicone).
Lack of normal glandular tissue, diffuse fatty tissue throughout the neobreast and distorted normal breast architecture is the common sonographic picture.
A baseline MRI may be needed to distinguish post surgical changes from local malignancy recurrence.
b)Post operative changes:
Picture similar to early fat necrosis such as edematous changes with skin thickening is detected.
A scar overlying an area of architectural distortion is the usual non worrying sonographic picture with no fluid nor soft tissue localization.
Gray scale ultrasonography is of limited use to assess lumpectomy site and MRI may be needed to distinguish thick irregular fibrotic scar from local recurrence/residual.
c)Post radiation changes:
Diffuse edematous changes, skin thickening and long term fatty change is the usual picture sharply limited to the radiation site.
d)Hormonal therapy changes:
Combined estrogen/progesterone therapy may be used as replacement therapy in post menopausal females or as part of the treatment regimen in breast cancer.
Usually it presents as bilateral symmetrical patch of increased breast echogenicity specially in females with diffusely fatty breasts.
Mammographic pictures with complementary sonographic examination are usually sufficient diagnostic tools.
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