Answers

Short answers

1 The left breast has a large ill defined, lobulated, and enhancing lesion in the centre, with surrounding satellite nodules. The right breast has a smaller, medially located, ill defined enhancing nodule. Both masses have associated pathological circulation, which is more marked on the left.

2 The lesions are consistent with bilateral breast carcinoma, which is multifocal on the left. They are probably malignant—they enhance avidly, are irregular with ill defined margins, have pathological circulation, and satellite lesions are seen on the left.

3 In younger symptomatic patients with prominent glandular tissue and dense mammograms where lesions can be obscured, magnetic resonance imaging often provides reassurance that no lesion is present. It is the best method for assessing breast implants for suspected leakage and looking for tumour recurrence after breast surgery.^{1 2 3 4 5 6} It is also useful for evaluating multifocal or lobular carcinoma or suspected chest wall invasion,^{1 2 3 4 5 6} and it has been proposed as a primary screening tool in young high risk BCRA positive patients.^{7 8 9 10 11}

4 Firstly, establish a histological diagnosis. Focused ultrasound of the medial right breast identified a 12 mm lesion, so ultrasound guided core biopsy was carried out. Sample biopsies of the central left breast at the level of the abnormality confirmed invasive lobular carcinoma bilaterally. Clinical examination, needle biopsy, and imaging all play complementary roles in such cases. The management of lobular carcinoma is complex and may include surgery, hormone therapy (depending on oestrogen receptor status), chemotherapy, and radiotherapy.

Long answers
1 Radiological abnormalities
The magnetic resonance image showed a large ill defined, lobulated, and enhancing lesion located centrally within the left breast surrounded by satellite nodules. A smaller ill defined enhancing nodule was also seen medially within the right breast. Both these masses showed pathological circulation, which was more marked on the left.

View larger version (140K): [in this window] [in a new window] [PowerPoint Slide for Teaching]   Fig 2 An axial post-contrast, fat saturated magnetic resonance image through the superior portion of the breasts. A large ill defined, lobulated, and enhancing lesion (A) is seen centrally within the left breast with surrounding satellite nodules. A smaller ill defined enhancing nodule is also noted medially within the right breast (B). These masses both show pathological circulation, which is more marked on the left (C)

 
2 Likely diagnosis
These findings are consistent with bilateral breast carcinoma, which is multifocal on the left. These lesions are likely to be malignant because they are spiculated, enhance avidly, and are irregular with ill defined margins. The associated pathological circulation and the satellite lesions on the left are also in keeping with invasive malignancy.¹ Further features of malignancy on magnetic resonance imaging are rapid enhancement and washout characteristics.

3 Indications for breast magnetic resonance imaging in everyday practice
Magnetic resonance imaging of the breast is being increasingly used in everyday practice as a problem solving tool with a widening spectrum of potential applications. It is often helpful in patients who present with a palpable abnormality, but where initial breast imaging is negative or inconclusive (as in our case).

In patients with prominent glandular tissue and dense mammograms, particularly younger women, where lesions can be obscured, magnetic resonance imaging can be especially helpful in reassuring both patient and clinician that no lesion is present. It is the technique of choice when assessing breast implants for suspected leakage and looking for suspected tumour recurrence after breast surgery.^{1 2 3 4 5 6} Other indications for breast magnetic resonance imaging include evaluation of multifocal or lobular carcinoma or where chest wall invasion is suspected.^{1 2 3 4 5 6} Magnetic resonance imaging has also been proposed as a primary screening tool in young high risk BCRA positive patients.^{7 8 9 10 11}

Although magnetic resonance imaging is a useful problem solving tool in breast imaging, it does have disadvantages and contraindications. A dedicated breast coil, which can be uncomfortable, is required. The scan can last up to 30 minutes and patients may feel claustrophobic, which results in a high failure rate. The technique is increasingly available in most breast units but is expensive compared with other breast imaging modalities. Magnetic resonance imaging can also pick up incidental abnormalities and lead to unnecessary additional surgery, investigation, and stress for the patient.^{3 4 5 6}

4 Further management
The immediate further management is to establish a histological diagnosis. This was achieved by focused ultrasound of the medial right breast, which identified a 12 mm lesion. Ultrasound guided core biopsy under local anaesthesia was then performed. Sample biopsies were also taken from the central area of the left breast using ultrasound, and these biopsies confirmed invasive lobular carcinoma bilaterally. Alternatively, surgical excision biopsy or magnetic resonance imaging guided biopsy (although not widely available) could have been used to obtain samples.

Infiltrating lobular carcinoma makes up 5-10% of all invasive breast carcinomas.¹ The median age at presentation is 45-56 years, with 2% of cases occurring in women under 35.^{1 2} It is the second most common form of the disease after ductal carcinoma. Thirty per cent to 50% of patients develop a second primary in the same or contralateral breast within 20 years.¹ It is the most commonly missed breast cancer overall—it is difficult to detect mammographically and clinically, and it has a 19-43% false negative rate radiologically (occult in dense breast tissue).^{1 2} Because of the tendency for multifocality and bilaterality, once lobar carcinoma has been identified, magnetic resonance imaging is increasingly being used to screen the remaining breast for lesions.

Disease is multicentric in 30% of patients and bilateral in 10%. The tumour tends to grow around ducts, vessels, and lobules without destruction of anatomical structures (targetoid growth). There is also a propensity for desmoplastic stromal reaction. Prognosis is poor, often because of the late diagnosis.^{1 2}

Lobular carcinoma is managed by surgery, hormone therapy (depending on oestrogen receptor status), chemotherapy, and radiotherapy.

Patient outcome

The patient underwent bilateral mastectomy with axillary node clearance. She was referred for chemotherapy, and because the tumour was oestrogen receptor positive, she will also receive hormone therapy.

Cite this as: BMJ 2009;339:b4316