Invasive Lobular Carcinoma of Breast Presenting with Left Sterno-chondral Junction Swelling. A Case Report.

Invasive Lobular Carcinoma of Breast Presenting with Left Sterno-chondral Junction Swelling. A Case Report.

ABSTRACT

Invasive Lobular Carcinoma of the breast is less common than Invasive Ductal Carcinoma and the presentation can be different from other types of breast carcinomas. It can present as diffuse swelling or thickening of breast rather than a mass. Sometimes, it can present as metastatic deposits from a very small primary breast lesion. These make the diagnosis of this type of breast carcinoma difficult and challenging for the radiologist and surgeon.

We describe a case of Invasive Lobular Carcinoma of the breast, which presented with a left sterno-chondral metastasis and discuss the imaging findings and treatment of this condition.

Key Words: Invasive Lobular Carcinoma, mammography, sterno-chondral metastasis.

INTRODUCTION

Invasive Lobular Carcinoma (ILC) of the breast is far less common than Invasive Ductal Carcinoma (IDC), consisting about 8-14% of all breast carcinomas ¹.

ILC can be more difficult to detect by mammography, as it can present as diffuse swelling or thickening rather than a mass with distinct borders like IDC. It may also occur in combination with IDC. The largest published paper of 4140 cases of ILC to date¹ reported that it has distinctive clinical and biologic characteristics compared with IDC. Lobular carcinomas are more likely to occur in older patients, (with median age of 64.6.years), to be larger in size, Oestrogen-receptor (ER) and Progestogen-receptor (PgR) positive, and to have normal p53 status and low Epithelial Growth Factor Receptor (EGFR) and HER-2. The incidence of contra-lateral breast cancer in women with ILC is nearly double the incidence in women with IDC (1).

We wish to report a case of ILC in a relatively young woman with a slow-growing tumour present for over 5 years, and who subsequently developed an associated sterno-chondral metastasis.

A 39-year-old woman presented with an enlarging left breast lump that she had felt for about 5 years. Three years earlier, her general practitioner was of the opinion that the lump she had was a benign tumour. No histological verification was made, and she has been not followed up. About two years before presentation she discovered a new hard painless lump in the region of the upper inner quadrant of the same breast. She has some investigation done including blood investigations and was found to have an elevated CA 15-3 level. There was no history of nipple discharge, loss of weight or appetite.

Physical examination revealed a slim anxious woman with no pallor or jaundice. Breast examination revealed bilaterally small breasts. A lump was visible as a protuberance under the skin in the left breast at 6 o’clock position. It was hard and measured about 6cms in size. There was no nipple inversion. There was also a hard lump felt over the region of the second left sterno-chondral junction. Palpation of the left axilla revealed multiple enlarged lymph nodes. Examination of the chest, cardiovascular and abdomen were unremarkable.

She refused mammographic examination. Breast Ultrasound showed an ovoid well-circumscribed mass with microlobulated margins in the left breast at 6 o’clock position, measuring 3.6x2.9x2.1cm (Figure 1).

Figure 1: Ultrasound scan of the palpable mass at left 6 o’clock position shows an ovoid mass with microlobulated margins and heterogenous internal echogenicity lesion with increased vascularity. Core biopsy confirmed Invasive Lobular Carcinoma.

Colour Doppler Flow Imaging showed that it was vascular with multiple penentrating vessels. A lump arising from the second left sterno-chondral junction was also detected (Figure 2).

Figure 2: Ultrasound scan of the bony mass arising from the second sterno-chondral junction shows a heterogenous echogenocity mass with increased vascularity.

Two other smaller avascular ovoid lesions with well-defined thin echogenic margins were also detected in the left breast at 10 o’clock position measuring 1.4x1.0cm (Figure 3).

Figure 3: Left Breast Ultrasound scan also showed a well-marginated homogenous and vascular ovoid lesion at 10 o’clock position with homogenous internal echoes and thin echogenic margin, likely to represent a benign lesion. This showed no enhancement on contrast MRI.

These lesions appeared benign and suggestive of fibroadenomas. Contrast-enhanced MR with subtraction showed that the left 6 o’clock lesions was heterogenously enhancing and measures 4.0x2.3x3.6cm (Figure 4).

Figure 4: Axial Breast MR images (each 4mm in thickness) shows an avidly enhancing well-defined mass at the left 6 o’clock position. Core Biopsy showed Invasive Lobular Carcinoma.

A second enhancing lesion corresponded in site to the left sterno-chondral junction lesion. It measured 2.0x3.0x2.0cm and displayed a non-enhancing portion, consistent with central necrosis (Figure 5). CT of chest and abdomen were unremarkable.

Figure 5: Axial MR images showing a peripherally enhancing left sterno-chondral lesion with central necrosis. FNAC showed metastasis compatible with a primary Invasive Lobular Carcinoma of the breast.

Core biopsy of the left 6 o’clock breast lump performed using a 14G Monopty needle confirmed ILC with predominant in-situ component. Fine needle aspiration cytology (FNAC) of the costo-chondral lump confirmed the diagnosis of bony metastasis, compatible with a primary breast ILC.

The patient was treated with 5 cycles of chemotherapy with intravenous Adriamycin 80mg and Docetaxel 80mg. The pre-treatment CA15-3 of 97 fell to 30.7. Sequential follow-up ultrasound showed progressive shringkage of the left 6 o’clock breast mass, and no change in the two benign-looking lesions. There is also complete disappearance of the left sternochondral mass and axillary lymph nodes. Left mastectomy and axillary clearance were performed subsequently. Pathologic examination of the excised specimens showed a 1cm tumour mass, arranged mainly as clusters and islands with tumour cells forming cords, Indian files and tagetoid pattern. There was necrosis in the centre of the tumour nests, and desmoplastic reaction in the surrounding stroma. LCIS comprised 30-40% of tumour volume. Tumour cells were positive for ER and cerb-2 and are negative for PgR. One of 15 lymph nodes was positive for metastases. Bloom-Richardson grading was Grade 1. She was well at clinical and imaging follow-up 6 months after surgery.

Lobular Carcinomas of the Breast are classified into in-situ and invasive forms. Invasive Lobular Carcinoma (ILC) of the breast can be difficult to diagnose with mammography because of subtle changes that mimic normal breast parenchyma, or a mass that is poorly delineated on clinical breast examination and mammography. It tends to be multifocal and bilateral in 20-29% ¹.

Pathologically, ILC consists of small round cells that often invade the surrounding tissue in thin strands, often only one cell in width without provoking the usual desmoplastic response as in IDC. These cells are bland in appearance with scant cytoplasm and may encircle ducts, whilst preserving the architecture of the ducts ². They infiltrate the stroma in single Indian file and do not incite any substantial connective tissue response. They often fail to form distinct masses and have an increased propensity for multifocal and multicentric distribution ¹. These unique histological features may contribute to delay in diagnosis and treatment. The uniform appearance of bland tumour cells that lack cellular atypia, often with a low mitotic rate make the lobular carcinoma cells more difficult to detect in metastatic lymph nodes. Thus nodal metastases are often missed with ILC ¹. The metastatic pattern for ILC also differs from that of IDC. Advanced ILC is more likely to spread to the peritoneum, ovary and gastro-intestinal system, and less likely to affect the lungs, pleura and CNS, compared to IDC ¹.

The histo-pathological features of ILC contribute to its mammographuc features, and several groups have described the mammographic findings in ILC ^{3, 4, 5}. In a retrospective review of 137 cases of ILC, Hilleren et al. reported that 16% appeared mammographically occult or benign. Of those visible mammographically, more than one third appeared as vague asymmetries, poorly defined opacities or architectural distortion ³. Micro-calcifications were seen in 2- 24% ^{3, 4, 5}. It is postulated that the lack of ductal invasion or obstruction may explain why microcalcifications are less often seen with these tumours compared to IDC ³. ILC is associated with a false negative rate of mammographic diagnosis of 16%-19% ⁵. The tendency of ILC to grow in multicentric foci with normal tissue in between may contribute to the relatively low radiographic density of the lesion and the absence of a well-defined discrete tumour mass ³.

Harvey et al reported an apparent ipsilateral decrease in breast size on mammography as a common finding with large ILC ⁶. The characteristics of ILC that may explain these findings are the bandlike infiltrating tumour, its association with loose but diffuse collagen formation, and frequent microscopic skip areas. These histological findings could cause thickening at physical examination without a discrete mass. The ipsilateral decrease in apparent mammographic size is probably related to reduced compressibility of the breast and may explain why this tumour is better seen in the craniocaudal view ^{4, 7}.

Paramugul et. al in 1995, reported a sensitivity of 68% with ultrasound using a 7.5 MHz transducer in the detection of ILC. This compared with 89% for mammography. The average size of ILC in the series was 2.2cm ⁸. Although 53% of cases in the series exhibited patterns that include hypoechoic irregularly marginated masses, heterogenous internal echoes and distal acoustic attenuation, the other cases of ILC displayed a variety of the above features in combination with features more commonly associated with benign lesions such as smooth margin, homogenous internal echogenicity and absence of acoustic attenuation ⁸.

Butler et. al. subsequently reported a series of 81 cases of ILC in which he found that ultrasound, using a 10MHz transducer to be a useful adjunct investigation in patients with subtle mammographic findings, with a sensitivity was 87%. The most common sonographic appearance of ILC was a heterogenous hypoechoic mass with ill-defined margins and posterior acoustic shadowing seen in 60.5% of tumours. Of the remaining 32 tumours, 12 showed focal shadowing without a discrete mass, 10 appeared as a lobulated well-circumscribed mass, and 12 were sonographically invisible ⁹. Correlation of the ultrasound features of the lesions was made with the histological cell types of the tumours. The five histological subtypes of ILC were classic, pleomorphic, signet, alveolar and solid. Although there may be considerable overlap in the histological subtypes, the classic ILC tended to present as focal shadowing without a discrete mass. The more aggressive pleomorphic type typically were seen as a shadowing mass while the other subtypes were most likely to be seen on ultrasound as a lobulated well-circumscribed mass ⁹.

MRI has been reported to be more sensitive than mammography and ultrasound in the detection of breast carcinoma and assessing disease extent before surgery. Qayyum et. al. observed three basic patterns of ILC. The most common pattern, observed in eight of 13 patients was of multiple enhancing foci with either connecting enhancing strands or non-enhancing intervening tissue ¹⁰, consistent with its propensity for multifocal disease.

This case report is of a patient with ILC with delayed diagnosis. This was partly due to its well-circumscribed appearance mimicking a benign lesion, a recognized but uncommon presentation. Colour Doppler Flow Imaging was extremely useful in showing the presence of multiple penetrating vessels within the tumour, thus increasing our index of suspicion. MRI was also a useful additional investigation to further identify the other lesions detected on Ultrasound. These proved to be benign fibroadenomas on the mastectomy specimen. MRI was also able to confirm the bony origin of the second palpable mass which was later proven to be a metastasis.