Image of the Month

Figure 1. A 15 × 10-cm mass in the patient's right breast grew rapidly during the past 8 to 12 weeks. A "cyst" had been noted previously.

Figure 2.Operative specimen of right total mastectomy. Note the cystic appearance of the cystosarcoma phyllodes tumor.

Figure 3.Appearance of patient after right breast reconstruction and left breast reduction.

Based on the patient's history, physical examination, and the atypical stromal cells on fine-needle aspiration, a presumptive diagnosis of a malignant cystosarcoma phyllodes tumor (Müller tumor) of the right breast was made. The patient underwent a total right mastectomy without axillary dissection (Figure 2). At the patient's request, the right breast was immediately reconstructed with a right-sided latissimus dorsi myocutaneous flap and a saline implant by a plastic surgeon. Reduction mammoplasty of the left breast was also performed (Figure 3).

Final pathology described a 15 × 10 × 9-cm malignant phyllodes tumor with extensive myxoid change. The tumor was circumscribed, the margins of resection were clear, there was no involvement of the skin of the breast, nipple, or vascular channels, and there was marked pleomorphism and anaplasia. The patient received no further therapy and is being followed up by the surgery and medical oncology services. A physical examination and mammogram of the left breast both had normal findings at 20 months following right mastectomy and reconstruction.

Originally named by Johannes Müller in 1838, the term cystosarcoma phyllodes refers to an uncommon tumor with a cystic and lobulated appearance that most commonly appears in the female breast.^1,2 Cystosarcoma phyllodes accounts for approximately 0.5% to 1.0% of all breast tumors.^3,4 The average age of onset is 45 years, but deaths from metastatic sarcoma have been reported in adolescent females.^5,6 A solitary and large unilateral breast mass is the usual sign, and approximately 25% of patients complain of recent rapid growth in a known breast mass.⁷

An ultrasound of a cystosarcoma phyllodes tumor will demonstrate a solid hypoechoic mass. On mammography, there will be a nonspiculated soft tissue mass that may represent either a benign or a malignant variant.⁸

A benign cystosarcoma phyllodes resembles a fibroadenoma histologically but has increased stromal cellularity.^2,9 There is not, however, uniform agreement about the histologic criteria that separate benign from malignant variants. In one review of the pathological specimens from 26 patients with cystosarcoma phyllodes, stromal overgrowth was found to be a significant predictor of metastatic spread and death of the patient.⁹ Stromal overgrowth was defined as "mesenchymal proliferation with complete absence of a ductal epithelial element in an area greater than one low power (×40) field."⁹(p2287)

The surgical treatment for smaller lesions is local excision with clear margins around the tumor. Because phyllodes tumors do not have true capsules, reexcision is necessary when the lesion is diagnosed on postoperative histologic sections and the margins are unclear.⁴ Larger tumors and recurrences of borderline and malignant tumors are treated with total mastectomy with simultaneous reconstruction based on patient preference.¹⁰ Axillary dissection is not indicated in the absence of clinically involved nodes on preoperative examination.¹¹ There is no indication for postoperative chemotherapy after the excision of malignant tumors. Postoperative radiation therapy has been suggested for large tumors or for recurrences involving the skin or fascia of the pectoralis major muscle.³ In a series from M. D. Anderson Hospital and Tumor Institute (Houston, Tex), 7 (27%) of 26 patients died of uncontrolled local recurrence or metastatic disease at a mean period of 30 months following resection.⁹

Corresponding author and reprints: David V. Feliciano, MD, Department of Surgery, Grady Memorial Hospital, 69 Butler St SE, Atlanta, GA 30303 (e-mail: dfelici@emory.edu).