Osteogenic sarcoma of the breast tissue can arise from a pre-existing benign or malignant neoplasm of the breast or may arise from previously normal breast tissue as non-phylloides sarcoma. It is known to differentiate from the connective tissue elements of fibroadenomas and has been reported following intraductal papilloma [3
]. Breast osteosarcoma can also arise as an osseous metaplasia of a primary carcinoma of the breast and as a whole or partial metaplastic replacement of phylloides tumor stroma [15
]. In its pure form and in exceptional cases, osteogenic sarcoma can arise from the soft tissues of a previously normal breast [17
]. To diagnose primary breast osteosarcoma, an osteogenic sarcoma arising from the underlying chest wall bony cage and infiltrating the breast tissue must be excluded. From findings at surgery and from the pathology report, our patient did not have gross or microscopic chest wall osteosarcoma extending to the breast. The absence of demonstrable metaplastic transformation of a pre-existing fibroadenoma or phylloides tumor at histology among others, suggests that the case presented could be an example of breast sarcoma arising from previously normal breast tissue.
Almost all patients with osteogenic sarcoma present like those with other benign or malignant breast lesions. Clinically, the breast lump is of varying consistency and may be rapidly growing. At the time of presentation, most patients have developed metastasis in different parts of the body including the chest and bones, though this was not the case with our patient [18
]. The two patients from our centre – this case and the earlier reported one [11
] – presented for definitive treatment about one year after noticing breast lumps and when the tumors were already locally advanced. This is typical of breast cancer patients about 80 percent of who present late to our oncology clinic [19
]. Mammographic findings vary. Most present as large masses with relatively well-defined margins and lobulated borders, often containing coarse or dense calcifications, which are sometimes similar to fibroadenomas [20
]. Where available intense focal intake of 99mTc-diphosphonate, a specific radionuclide marker for osteoid tumoral tissue, in a soft-tissue tumor is strongly suggestive of bone-forming neoplasms. This may be useful in the radiological diagnosis of breast osteosarcoma [20
]. Serum alkaline phosphatase is known to be elevated in patients with osteoid-forming neoplasms [20
]. Though non-specific, these tests may be useful adjuncts in the diagnosis of osteogenic sarcoma of the breast. Definitive diagnosis hinges on exclusion of an osteogenic sarcoma arising from underlying ribs and sternum, and a demonstration of osteosarcomatous matrix by histology. Where facilities are available, immunohistochemical demonstration of vimentin with absence of epithelial, neural, muscular and other markers suggest the diagnosis of osteogenic sarcoma. This may be confirmed by ultrastructural examination of the osteoid-like areas, which will reveal collagen fibers enmeshed with crystalline material confirming the presence of osteoid [23
The rarity of this condition precludes any one institution from gathering enough cases from which a definitive assessment of the effectiveness of treatment options can be made or clinical trials conducted. It follows however, that management of sarcomas elsewhere should generally apply in the management of this disease entity. It is debatable whether modified radical mastectomy should be done instead of simple mastectomy with axillary node dissection where there is clinical evidence of lymph node involvement. Adequate surgical excision should ensure tumor free margins and be supplemented by intraoperative evaluation of lymph nodes. Osteosarcomas are aggressive tumors with a propensity for blood-borne rather than lymphatic spread [13
]. Because of high risk of recurrence, chest wall irradiation and regular follow-up for early detection of loco-regional recurrence is indicated. The role of combination chemotherapy is uncertain but it may be considered in the presence of systemic metastasis. However, these have not been proven to offer additional benefits.
Because these tumors tend to attain large sizes and the role of neoadjuvant chemotherapy to down-stage them is unclear, patients occasionally require chest wall reconstruction. Myocutaneous flaps are preferred because they can tolerate radiotherapy with minimal risk of tissue loss [24
]. Latissimus dorsi
musculocutaneous flap was used for our patient because of the ease of raising it, its reliability and cosmetic acceptability of the scar at the donor site, which is hidden at the back of the patient where it is covered with regular clothing. The major disadvantage of the flap is that patient may have to be repositioned during the course of surgery to ensure improved access.