Bilateral breast metastases of a renal carcinoma: a case report and review of the literature
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* S Ganapathi
* G Evans
* R Hargest

## Summary

Metastatic tumours account for <1% of all breast malignancies, most originating in the contralateral breast. An 88-year-old woman presented with bilateral breast lumps 4 years after radical nephrectomy for a T2N0M0 renal cancer. Mammography showed a circumscribed 15 mm mass just below and medial to the left nipple without any micro-calcification. Ultrasound scan showed the presence of a solid vascular mass in the left breast; a guided core biopsy confirmed it as a metastatic renal cell carcinoma. Left simple mastectomy and excision of right breast lump was done. Histology of both lesions confirmed them as metastatic deposits. Bilateral breast metastasis from a renal cancer is very rare and this is the second reported case. This case illustrates the potential for rare sites of metastases and for the consideration of metastasis in the presence of previous renal cancer. Recognition as metastatic neoplasm is important to prevent unnecessary radical procedures.

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## BACKGROUND

This is the second case report of bilateral metastases in the breast secondary to renal cancer, the previous instance involving a 14-year-old girl.

*   The case illustrates the potential for rare sites of metastases and for the consideration of metastasis in the presence of previous renal cancer.

*   It also illustrates the wide range of age that this disease can involve.

*   Recognition of the neoplasm as metastatic is important to prevent unnecessary radical procedures.

## CASE PRESENTATION

An 88-year-old woman presented to the breast clinic with a lump in the left breast 4 years after radical nephrectomy for a T2N0M0 renal cancer. An asymptomatic right breast lump was identified at examination. Both the lumps were in the lower inner quadrant but the lump in the right breast was close to the nipple. With the suspicion of primary carcinoma of the breast, she was investigated.

## INVESTIGATIONS

Mammography showed a circumscribed 15 mm mass just below and medial to the left nipple without any micro-calcification (fig 1). Ultrasound scan showed the presence of a solid vascular mass in the left breast and a guided core biopsy was taken. The lump was shown to be a metastatic clear cell carcinomatous deposit and was very similar to the post-surgical histopathology after radical nephrectomy (fig 2). Computed tomography (CT) scan of the breasts showed the lump in the right breast to be highly suspicious of metastatic lesion. CT scan of the thorax showed a suspicious deposit in the right lung and enlarged mediastinal lymph nodes. There was no evidence of any local recurrence or any tumour in the left kidney.

![Figure 1](http://casereports.bmj.com/https://casereports.bmj.com/content/casereports/2008/bcr.06.2008.0239/F1.medium.gif)

[Figure 1](http://casereports.bmj.com/content/2008/bcr.06.2008.0239/F1)

Figure 1 Mammogram of left breast lump showing a circumscribed 15 mm mass without microcalcification.

![Figure 2](http://casereports.bmj.com/https://casereports.bmj.com/content/casereports/2008/bcr.06.2008.0239/F2.medium.gif)

[Figure 2](http://casereports.bmj.com/content/2008/bcr.06.2008.0239/F2)

Figure 2 Clear cell carcinoma of right kidney.

## DIFFERENTIAL DIAGNOSIS

*   Primary bilateral breast carcinoma.

## TREATMENT

With a palliative intent, the patient was treated with left simple mastectomy and excision of the right breast lump. Histology of both the lesions confirmed them as metastatic deposits (figs 3–5).

![Figure 3](http://casereports.bmj.com/https://casereports.bmj.com/content/casereports/2008/bcr.06.2008.0239/F3.medium.gif)

[Figure 3](http://casereports.bmj.com/content/2008/bcr.06.2008.0239/F3)

Figure 3 Cut-section of right breast lump showing a vascular tumour with areas of necrosis.

![Figure 4](http://casereports.bmj.com/https://casereports.bmj.com/content/casereports/2008/bcr.06.2008.0239/F4.medium.gif)

[Figure 4](http://casereports.bmj.com/content/2008/bcr.06.2008.0239/F4)

Figure 4 Clear cell carcinoma of right breast which is very similar to the histology of previous renal carcinoma.

![Figure 5](http://casereports.bmj.com/https://casereports.bmj.com/content/casereports/2008/bcr.06.2008.0239/F5.medium.gif)

[Figure 5](http://casereports.bmj.com/content/2008/bcr.06.2008.0239/F5)

Figure 5 Clear cell carcinoma of left breast which is also very similar to the histology of previous renal carcinoma.

## OUTCOME AND FOLLOW-UP

Follow up at 1 and 6 months following the operation did not reveal any clinical evidence of tumour recurrence.

## DISCUSSION

Metastatic tumours account for <1% of all breast malignancies, most originating in the contralateral breast.1 Excluding neoplasms from contralateral breast and haematopoietic malignancies, about 400 cases of solid tumour metastasis to the breast have been reported. There have been 15 cases of metastatic renal cell carcinoma to the breast. Among them 12 cases were breast metastasis identified between 1 and 18 years after nephrectomy, including bilateral breast metastasis in a 14-year-old girl.2 Breast metastasis was the initial presenting symptom in two cases. In one man a palpable metastatic lesion arose from the skin of the breast. A crude survival rate of 10.9 months has been reported.3

Metastatic tumours to the breast are usually asymptomatic with the lesions most commonly solitary and discrete, located superficially in the upper outer quadrant of the breast. Pain, tenderness or discharge are rare. The overlying skin is rarely dimpled or adherent to the tumour. The breast lesion has been the first manifestation of metastatic disease in 25% of the cases in which the data were available. The common sources of primary tumour for breast metastases in the order of frequency are the contralateral breast, the leukaemia/lymphoma group, malignant melanoma and lung cancer.4

The breast location can be explained by the spread of neoplastic cells from the renal vein into the inferior vena cava (IVC) and then through the pulmonary circulation, reaching the arterial circulation before finally spreading throughout the whole organism.5 The majority of the presentations (80%) have been metachronous metastases which have been found to carry a better prognosis than the synchronous metastases.1

The metastatic behaviour of renal cell carcinoma is frequently bizarre and unpredictable. The clinical literature includes a surprisingly high number of organs involved in metastases. The number is even higher in autopsy series, which include metastatic sites never or rarely reported in clinical studies.

Unlike primary breast carcinoma, metastases do not generally involve the overlying skin and usually lack microcalcifications. In addition mammographic sizes of the metastatic tumour are comparable, whereas the clinically palpable size of the primary tumour due to the associated desmoplasia is usually larger than the mammographic size. Rapid growth is another feature characteristic of metastatic tumours.6

#### LEARNING POINTS

*   Metastatic tumours are uncommon in the breast. Bilateral breast metastasis from a renal cancer is very rare and this is the second reported case.

*   The case illustrates the potential for rare sites of metastases and for the consideration of secondaries in the presence of previous renal cancer.

*   Recognition of the neoplasm as metastatic is important to prevent unnecessary radical procedures.

## Footnotes

*   **Competing interests:** none.

*   **Patient consent:** Patient/guardian consent was obtained for publication

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