Solitary breast metastasis from myxoid liposarcoma

Background: Metastasis to the breast from nonmammary malignancies is rare, and mostly involves patients in a pre-terminal condition with systemic metastases outside the breast. Lymphoma and leukemia, melanoma, and lung carcinoma are the most common primary malignancies to cause breast metastasis; metastasis of soft tissue sarcoma to the breast is very rare. Here, we report a case of primary lower-extremity myxoid liposarcoma with the development of a solitary metastasis to the breast. To the best of our knowledge, no isolated case reports of solitary breast metastasis by myxoid liposarcoma have been previously reported in the English-language literature. Case presentation: The patient, a 66-year-old woman, had been previously diagnosed with myxoid liposarcoma of the right thigh. At 21 months after complete surgical resection of the primary tumor with negative margins, a palpable tumor was identified in the patient's left breast. Needle biopsy revealed the presence of metastatic liposarcoma; positron emission tomography/computed tomography examination confirmed the metastasis as solitary, and no local recurrence of the primary tumor was identified. The patient underwent lumpectomy with negative margins and did not provide consent for adjuvant chemotherapy. As with the biopsy specimen and the total cleavage specimen, myxoid liposarcoma with metastasis to the breast was diagnosed. No recurrence or new metastases were observed five years after resection of the metastatic breast lesion. Conclusions: We have presented an extremely rare case of a solitary metastatic breast tumor arising from myxoid liposarcoma of the lower limbs. There is no standard treatment for the management of solitary breast metastasis from myxoid liposarcoma. Therefore, treatment should be guided by consideration of an individual patient's overall condition.