• Breast cancer
• lymphoma

The four patients described had an unexpected synchronous malignancy diagnosed during the workup for their breast cancer. It is a well-documented fact that patients with one treated malignancy are at an increased risk of developing a second tumour. However, the synchronous presentation of two malignancies is rare. In an autopsy study of 1870 known cancer deaths, 68 cases (3.6%) had multiple primaries, and only 15 (0.8%) of these were synchronous.1

We describe four patients who all presented within a 10-month time period to a regional hospital in Queensland Australia (table 1). This hospital treats on average 200 new breast cancer cases each year. To the best of our knowledge, this is the largest such case series in the English language literature, and it is remarkable considering the short time period over which the patients presented. Cox et al2 published a case series describing three patients who presented over a period of 15 years with breast carcinomas and coincidental axillary lymphoma, and there have been a number of similar single case reports.3–5

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Figure 1

Mastectomy specimen showing grade 2 invasive ductal carcinoma (H&E, original magnification ×200).

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Figure 2

Axillary lymph node specimen showing effacement of the normal architecture by a monotonous population of small malignant lymphocytes. A ‘proliferation centre’ (pale zone) which is characteristic of small lymphocytic lymphoma can be seen to the left. A microscopic metastatic deposit of breast carcinoma can be seen to the right, under the capsule (H&E, original magnification ×40).

Factors that have been suggested as contributing to the development of synchronous malignancies include advanced age of the patient, primary or cancer-related immunological impairment and genetic predisposition to cancer.6 As our population ages, this is likely to become a more frequent occurrence. The UK population is predicted to reach 65 million by 2016. In 2006, there were 4.7 million people in the UK aged 75 and over. The number is projected to increase to 5.5 million by 2016 and to 8.2 million by 2031, a rise of 76% over 25 years.

Two of the four patients described had both the breast cancer and the lymphoma occurring in the same lymph node. This has been rarely described in the literature. Possible explanations have been put forward to explain why this is an unusual finding, including the fact that the lymphoma may obliterate the lymphatic channels if it occurs first,6 or may lead to a local reduction in cytokine induced adhesion of breast cancer cells to the axillary lymph nodes.7 This situation could potentially impact on both staging and prognosis of the patient. Benoit et al describe a patient with breast cancer and negative sentinel lymph nodes.8 Complete level I/II axillary lymph node dissection diagnosed low-grade lymphoma. Metastatic breast carcinoma was found in one non-sentinel node which was free from lymphoma. Sentinel lymph-node biopsy alone would have led to incorrect staging and therefore potentially inadequate treatment of the breast cancer. As our two patients with lymph-node involvement had a clinically palpable lymphadenopathy, they progressed directly to axillary dissection, and their sentinel nodes were not identified. Therefore, we are unable to comment on whether they would have had negative sentinel nodes.

Patients with lymphoma tend to be chronically immunosuppressed. As well as predisposing them to the initial development of a second malignancy, it may also impact on its behaviour. Squamous-cell carcinoma has been noted to have an increased risk of metastasis and mortality in patients with chronic lymphocytic leukaemia.9 This more aggressive behaviour has been attributed to the patient's immunosuppresed state, and it is possible that breast cancer may behave similarly.

An important point highlighted by these cases is that, in the situation of obvious axillary lymphadenopathy and an impalpable breast primary, this does not always indicate metastatic disease. The clinician needs to maintain a high index of suspicion about the possibility of synchronous malignancies, and a biopsy from both breast and axilla may be required prior to planning surgery (table 1).

Synchronous malignancies pose both a diagnostic challenge to the pathologist and a management challenge to the clinician. If a patient has a negative sentinel node biopsy for carcinoma but is diagnosed as having an unexpected lymphoma, the possibility of a completion axillary dissection should be discussed, as this may impact on staging of the breast carcinoma. Also, a decision will need to be made regarding which malignancy should take priority with treatment, and thorough staging investigations will need to be performed for both primaries.