CASE 9658 Published on 29.11.2011

A case of mammographically occult breast cancer with sonological features of fat necrosis


Breast imaging

Case Type

Clinical Cases


Radhamma A, Malhotra A, Tsukagoshi D, El Sheikh S, Holloway B

Royal Free Hospital,
Pond Street,
London, NW3 2QG

69 years, female

Area of Interest Breast ; Imaging Technique Mammography, MR, Ultrasound, Experimental
Clinical History
A 69-year-old Caucasian lady presented to the breast clinic with a 2-week history of nodular thickening in the lower outer quadrant of the left breast. No family history of breast or ovarian cancer.
Clinical examination revealed 2x1 cm hard palpable mass with skin thickening.
Imaging Findings
Full-field digital mammography (Figs. 1 and 2) showed minimally dense breast parenchyma bilaterally. No suspicious opacities or micro calcification (M1).
Targeted US (Fig. 3) showed a principally irregular hyper echoic lesion (20x15 mm) which appeared to merge with the surrounding breast tissue. No enlarged ipsilateral axillary nodes. A diagnosis of U3 lesion (U3-sonographically indeterminate) – probable fat necrosis was given.
With clinically suspicious mass, a negative mammogram and indeterminate lesion sonographically, a core biopsy was done.
This case was discussed in the MDT and the histology was Grade 1 invasive lobular carcinoma (Figs. 4 and 5).
With the above histology MR imaging of the breast with contrast material was requested (Figs. 6 and 7)
An MRI, done 7 days after biopsy, revealed a unifocal area of distortion and ill-defined enhancement measuring 3 cm in the lower outer quadrant of left breast corresponding to the known primary lesion on US. No pathology noted elsewhere.
Invasive lobular carcinomas (ILC) constitute 10% of all breast cancers [1] and are the second most common type of breast cancer after invasive ductal cancer.

Clinically ILCs do not normally form a lump as most women expect with breast cancer. Instead ILC more often causes a thickening of the tissue or fullness in one part of the breast. Commonest age group is 45–55 yrs. These tumours can be bilateral and multicentric.
Background density and diffuse histology are the principal causes of false-negative mammograms. It is widely accepted that mammography has a false-negative rate of 10–15% in detecting ILC than other invasive breast cancers [2]. These are mammographically negative because instead of forming a lump the cancer cells more typically spreads to the surrounding connective tissue in a line formation and fails to elicit a desmoplastic reaction when positive. The most common mammographic finding is as opacity with spiculated or ill defined margins (44–65%) [3]. Other presentations are with architectural distortion and asymmetry. Micro calcification is less than in ductal carcinoma with a reported prevalence of 0–24% [4].
USS is a valuable adjunct to mammogram with reported sensitivity for the detection of ILC ranging from 68–98% [5]. The most common manifestation is an irregular or angular mass with hypo echoic and heterogeneous internal echoes, ill defined or spiculated margins and posterior acoustic shadowing.
MR imaging is superior to USS and mammogram in detecting multifocality and multicentricity as well as in estimating tumour size [6]. More importantly it is shown to affect clinical management in 50% of the patients with ILC leading to changes in surgical management in 28% of cases [1]. It also provides valuable information about the presence of a residual tumour or of extensive or multifocal disease in women who have already undergone excision biopsy. At MRI the appearance of ILC varies as follows:
1. Solitary irregular or angular mass with spiculated or ill defined margins (31–43%)
2. Type II/III enhancing mass with multiple surrounding enhancing foci.
3. Multiple foci with enhancing interconnecting strands.
4. Architectural distortion.

The clinical and mammographic elusive nature of ILC makes the diagnosis and management of this neoplasm uniquely challenging compared with other invasive cancers. ILC gives varied imaging appearances and can be occult mammographically, sonologically and even in MRI. Despite these challenges however, imaging remains a fundamental tool in the detection and management of ILC and emphasises the importance of triple assessment in the management of these tumours.
Differential Diagnosis List
Unifocal Grade 1 Invasive lobular carcinoma (ILC) of left breast.
Fat necrosis
Invasive ductal carcinoma
Final Diagnosis
Unifocal Grade 1 Invasive lobular carcinoma (ILC) of left breast.
Case information
DOI: 10.1594/EURORAD/CASE.9658
ISSN: 1563-4086