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We present a case of metastatic adenocarcinoma of the breast in a patient who sustained a pathological fracture of the distal femur. Histology of the distal femur lesion excised at the time of endoprosthetic replacement confirmed this to be a primary chondrosarcoma. We have reviewed the literature and identified previously documented cases of concurrent breast carcinoma and chondrosarcoma of bone. A high index of suspicion is warranted and the diagnosis must be first confirmed before rushing to internal fixation (therapeutic or prophylactic) assuming them to be secondary bone lesions from the known primary cancer even in patients with multiple metastases.
Orthopaedic surgeons are usually involved when a patient with metastatic cancer sustains a pathological fracture from bony metastases. It is common practice to assume this to be a secondary deposit from the originally diagnosed primary tumour. Management decisions are usually based on this presumption. We present a case of pathological fracture of a distal femur in a patient with known metastatic breast carcinoma, which turned out to be another primary tumour, a chondrosarcoma. We present a review of similar cases from the literature and discuss the significance of this possibility.
A 56-year-old woman who was attending for inpatient chemotherapy felt her left knee give way when getting off the toilet. Weight bearing on the leg was not possible due to pain, and radiographs of her knee confirmed a supracondylar fracture of the left distal femur. She had metastatic breast carcinoma with lung secondaries and with on going chemotherapy was expected to survive longer than 6 weeks. An MRI scan was arranged to determine the extent of the deposit in the femur, in order to select the ideal fixation. MRI revealed extensive infiltration of the distal femur and this looked unsuitable for internal fixation (figure 1).
The primary breast tumour, diagnosed 3 years prior to the fracture, was an aggressive, poorly differentiated (grade 3) ductal carcinoma (oestrogen receptor, progesterone receptor and human epidermal growth factor receptor 2 negative; figure 2). The patient was initially treated with wide local excision and sentinel node biopsy, which showed that the margins were clear and lymph nodes were negative (T2 N0 M0). She had a right mastectomy for local recurrence and shortly afterwards was found to have pulmonary metastases. She received a number of different chemotherapy regimens. Most lung lesions responded and the remaining resistant nodule required wedge resection 2 years later.
The lesion in the distal femur was presumed to be a secondary deposit with a history of metastatic breast carcinoma.
The regional bone tumour unit was consulted for an expert opinion. The patient was transferred to the bone tumour unit and underwent endoprosthetic replacement of the distal femur. She was able to mobilise on the knee almost pain free for 8 weeks before eventually succumbing to a pulmonary embolism in spite of mechanical prophylaxis and enoxaparin in the perioperative period.
Histology from the excised distal femur did not show metastatic breast carcinoma as expected, but identified a primary chondrosarcoma (figure 3). Histology from the previous breast and lung biopsies were reviewed in multiple centres to exclude the possibility of misdiagnosed dedifferentiated chondrosarcoma spreading to breast and lung, and eventually two separate primary cancers were confirmed.
Primary chondrosarcoma of the breast, although very rare, has been reported previously.1 An extensive review of 132 636 cases of breast cancer between 1973 and 1998, in the Netherlands,2 identified 34 cases of concurrent breast cancer and cartilaginous tumours. There were 28 osteochondromas in the same group as well but a statistically similar incidence of concurrent osteochondromas was observed in patients with lung cancer. Out of the 34 cases, 18 were enchondromas and 15 chondrosarcomas, and involved mostly the femur or humerus (65%). All 34 had histological and immunohistochemical survey performed and cluster analysis did not reveal any associations with known syndromes or genetic traits. Their findings support the existence of a new hitherto unrecognised syndrome, characterised by an increased risk to develop breast cancer and also centrally originating cartilaginous tumours. There have been sporadic reports of concurrent breast carcinoma as well as bone chondrosarcoma in the literature.3 The possibility of an unidentified genetic mutation increasing susceptibility to multiple concurrent tumours cannot be ruled out, but has not yet been proven.3
In patients with metastatic cancer, pathological fractures are assumed to be a secondary deposit from the originally diagnosed primary tumour. Management decisions are usually based on this presumption. In this case, since the femoral lesion was not appropriate for stabilisation with internal fixation and required excision/replacement, we could make a definitive histological diagnosis of a different tumour. Even though this diagnosis has not changed the eventual outcome in our patient, orthopaedic surgeons should be aware of the possibility of two different primary tumours being present at the same time. Chosen surgical strategy should also consider further cancer treatment that may be required, such as radiotherapy, which may delay fracture healing and, of course, the life expectancy of the patient.
The authors would like to acknowledge Mr Simon Carter, Consultant in Orthopaedic Oncology, Royal Orthopaedic Hospital, Birmingham, for his help in feedback and advice on the case report, and for securing relevant information required.
Competing interests: None.
Patient consent: Not obtained.
Provenance and peer review: Not commissioned; externally peer reviewed.