Patient Data
Over the twelve-year period, 1,060 breast cancers were detected and of these nine were identified as being breast metastases from extramammary malignancies. Nine patients were included in this study with females being more commonly affected (6 females, 3 males). Mean and median onset age for breast metastasis was 62 years and 68 years, respectively, with a range of 15 years to 87 years.
In this study breast metastases from extramammary malignancies were rare, accounting for only 0.85% of all malignant neoplasms of the breast and reflects the incidence from current literature [1 - 5].
All patients presented for investigation of a clinically palpable breast mass (5 right breast masses, 4 left breast masses). At the time of presentation, seven patients had a known history of malignancy with two patients having no known history of malignancy.
Demographic characteristics of patients with breast metastases from extramammary malignancies are summarized in Table 1 (Figure 1).
Histology
The diagnosis of all breast masses in our group of nine patients was obtained histologically by ultrasound guided core biopsy.
The majority of cancers were lymphoma (n = 4), followed by lung carcinoma (n = 2).Other primary tumour sites include melanoma (n = 1), kidney (n = 1) and endometrium (n = 1). Our findings are consistent with previous reports in which lymphoma, lung carcinoma, melanoma and renal cell carcinoma were amongst the most common tumours to metastasize to the breast [1-5].
The histology of extramammary malignancies is shown in Table 2 (Figure 2).
Imaging Appearance
All nine patients were assessed sonographically and seven patients also had mammography performed. All patients proceeded to ultrasound guided core biopsy for tissue diagnosis.
Table 3(Figure 3) provides a summary of the imaging appearances of the malignant lesions.
The most common mammographic appearance was an uncalcified nodular density. No masses demonstrated mammographic macro- or microcalcification.
On ultrasound all masses were hypoechoic with either a well circumscribed margin (n=5) (Fig 4, 9, 10) or irregular angular margins (n=4) (Fig 5, 6, 7, 8).
The above imaging characteristics are in keeping with those demonstrated in other studies. Mammographically, breast metastases are most frequently described as round or oval masses with circumscribed margins. On ultrasound breast metastases typically present as hypoechoic masses with circumscribed or irregular margins [5]. Lesions with a well circumscribed margin may be mistaken as benign [3].
Breast metastases have been described as a solitary rapidly growing mass [5]and in our study all breast lesions were solitary.
Lymphoma
A total of four patients had breast lymphoma. Of the three patients who had mammography performed, only one lesion was visible as a uncalcified circumscribed mass. All four lesions were hypoechoic on ultrasound with three lesions demonstrating well circumscribed margins (Figure 4) and one irregular margins (Figure 5).
Published imaging studies describe breast lymphoma as predominantly oval nodules with well circumscribed margins. The histological type of all four cases in our study was B-Cell lymphoma, which according to the literature review accounts for 85%-95% of all cases of breast lymphoma [5].
Lymphoma Case 1
A 71 year old male with a twelve-month history of chronic B-cell lymphocytic leukaemia presented with a palpable left breast mass which proved to be chronic B-cell lymphocytic leukaemia within an island of lymphoid tissue.
Lymphoma Case 2
The youngest patient was a 15 year old girl who presented with an enlarging left breast mass (Figure 5). Three years prior to this presentation she had received a bone marrow transplant for lymphoblastic lymphoma of B-cell type.
Mammography was not performed. Ultrasound showed an irregular, hypoechoic, vascular 90mm mass along with left axillary lymphadenopathy. Core biopsy of the breast mass demonstrated malignant infiltration by acute lymphoblastic lymphoma of B-cell type in keeping with recurrence.
Lung Carcinoma
Two patients were found to have metastatic lung carcinoma of the breast.
Lung Cancer Case 1
A 67 year old female presented with a palpable left breast mass at the 10 o’clock position nine months following her diagnosis of small cell lung cancer. Mammography and ultrasound were performed (Figure 6).
Ultrasound guided core biopsy revealed a high-grade neuroendocrine carcinoma in keeping with metastatic small cell lung carcinoma.
Lung Cancer Case 2
69 year old previously well man presented with a palpable right breast mass. Mammography and ultrasound were performed (Figure 7).
Ultrasound guided core biopsy revealed a moderately differentiated squamous cell carcinoma.
Subsequent CT scan revealed left hilar and mediastinal lymphadenopathy. Bronchoscopy confirmed infiltrating moderately to well differentiated squamous cell carcinoma.
Melanoma Case
Two years the following excision of a malignant melanoma from her ventral abdominal wall a 44 year old woman presented with a palpable left breast mass at the 5-6 o’clock position (Figure 8).
Mammography demonstrated a subtle isodense, uncalcified nodule with well-defined margins. Ultrasound showed an irregular hypoechoic 17 mm mass with angular margins. Ultrasound guided core biopsy revealed malignant melanoma.
CT staging demonstrated the breast lesion to be an isolated metastasis.
Renal Cell Carcinoma Case
The oldest patient was an 87 year old man who was under observation for an indeterminate left renal mass that was incidentally diagnosed on CT (Figure 9). Two months later he presented with a left breast mass. Breast and left renal ultrasound were performed.
Ultrasound guided core biopsy of the left breast revealed metastatic renal cell carcinoma.
Endometrial Carcinoma Case
A 73 year old woman presented with a right breast mass on the background of known metastatic endometrial carcinoma. She was diagnosed with endometrial carcinoma seven years prior.
Mammography and breast ultrasound were performed (figure 10).
Ultrasound guided core biopsy confirmed metastatic endometrial adeno carcinoma to the right breast and axillary lymph node.
The prior month to this presentation she was found to have a solitary pulmonary metastasis. The preceding year she had a solitary cerebral metastasis which was excised (figure 11).
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