The disease processes discussed in this chapter are uncommon tumors: phyllodes tumors, sarcomas, lymphomas, melanomas, and metastases to the breast. As a group, these tumors are rare and heterogeneously diverse. Given their small numbers, there have been few large patient series or trials, and no large prospective trials will likely be performed. The majority of the literature consists of single-institution, retrospective studies/case reports with small numbers, varied follow-up, and inherent biases. Furthermore, these studies are difficult to compare as the definition, management, and treatment of these tumors have changed over time. Therefore, there are no established guidelines for the treatment of these uncommon tumors; patients with these rare tumors should be managed in a multidisciplinary fashion.
Phyllodes tumors represent a spectrum of fibroepithelial neoplasms that have biological behavior that is diverse and unpredictable. They account for less than 1% of all breast neoplasms.1,2 These tumors have also been referred to as cystosarcoma phyllodes, phylloides tumors, and periductalstromal tumors. The term cystosarcoma phyllodes was first introduced in 1838 by Johannes Mueller; "sarcoma" for the fleshy nature of the tumor and "phyllodes" for its leaf-like architecture.3 Mueller emphasized the benign nature of this tumor. The first report of histologically malignant features in these tumors was by Lee and Pack in 1931.4 In 1960, Lomonaco proposed the name tumor phyllodes to avoid any implications of biological behavior.5 The World Health Organization proposed phyllodes tumor to emphasize the putative origin of these tumors from specialized periductal stroma and to avoid the designation of sarcoma with its deceptive implication of malignancy for a majority of these tumors.6 These tumors can arise de novo, and less frequently from preexisting fibroadenomas or from the malignant transformation of benign phyllodes tumors.2
Phyllodes tumors occur over a wide age range from adolescents to the elderly, with the majority of tumors occurring in women in their 40s to 50s.1,2,7,8 These tumors can occur in young children and men. Women usually present with a palpable, firm-hard, discrete, mobile mass with an average size of 4 to 5 cm. Most tumors are unilateral and painless. Some women may give a history of a stable mass that grows rapidly. Larger tumors may cause stretching of the overlying skin and ulceration. All of these findings can be seen in both benign and malignant tumors. Compared with fibroadenomas, phyllodes tumors are seen more frequently in older patients and those with a history of rapid tumor growth and/or larger tumors. Palpable axillary lymphadenopathy can be identified in up to 20% of patients but is usually due to reactive changes as metastatic involvement is rare.9-11 In some instances, tumors may be multifocal, bilateral, or occur in ectopic breast tissue. In 1% to 2% of cases, an in situ or invasive breast carcinoma occurs within a phyllodes tumor.12 Also, patients can ...