Resection and Reconstruction of a Solitary Sternal Metastasis After Mastectomy for Breast Cancer: A Case Report and Review of the Literature

Ramona Hagmaier, MHS, PA-C; Hung T. Khong, MD; Carl Maltese, MD; Randy D. Proffitt, MD; and Adam I. Riker, MD
Published: Thursday, Mar 03, 2011

In May 2005, a 25-year-old female presented to her primary care physician complaining of a newly palpable breast mass that had grown to several centimeters over the course of a few months. A mammogram and ultrasound revealed a 3.6 x 3.4 cm left breast mass with several enlarged and suspicious lymph nodes. Adjacent soft tissue masses in the left axilla were deemed suspicious, ranging in size from 1 to 2 cm each. An ultrasound-guided core biopsy of the breast mass revealed a grade 3/3 infiltrating ductal carcinoma that was estrogen receptor/progesterone receptor (ER/PR) positive and HER2/neu 3 (ie, strongly positive). In June 2005, the patient began neoadjuvant chemotherapy with 4 treatments of dose-dense Adriamycin (doxorubicin) and Cytoxan (cyclophosphamide), followed by 2 cycles of Taxol (paclitaxel). Due to the development of severe peripheral neuropathy, her treatment regimen was changed to 2 cycles of Taxotere (docetaxel).

The patient completed neoadjuvant chemotherapy in November 2005 and underwent a left modified radical mastectomy, with the final pathology revealing a grade 3/3 infiltrating ductal carcinoma that was 3.2 cm, with associated high-grade comedo-type ductal carcinoma in situ (DCIS). All surgical margins were negative, and final pathology revealed a single lymph node involved with metastatic breast cancer. No reconstruction was performed at that time. She recovered from her operation and then received left chest wall radiation followed by adjuvant tamoxifen and trastuzumab therapy. Deemed responsible for an asymptomatic decrease in her ejection fraction, the trastuzumab was subsequently held for 3 months. Her ejection fraction returned to normal; further investigation showed that the decrease was not due to the trastuzumab, but rather the Adriamycin and possibly the adjuvant chest wall radiation. Trastuzumab was restarted in August 2006 and completed in October 2006, and her last ejection fraction was found to be within normal limits.

In November 2006, the patient developed new-onset midsternal pain that she described as constant and unrelenting. Analgesics and narcotics were required to achieve adequate pain control. A whole-body position emission tomography-computed tomography (PET/CT) scan revealed an area of intense hypermetabolic activity within the central and distal portion of the sternum, extending to and including the xiphoid process (Figure 1). This area was described as an expansile lytic lesion of the sternum with large areas of cortical bone destruction. A bone scan was otherwise negative. Her pain continued to increase in severity and her tamoxifen was discontinued. She was started on anastrazole, an aromatase inhibitor, and leuprolide therapy in an attempt to inhibit further growth of this likely sternal metastasis.

In March 2007, we proceeded with surgical intervention in collaboration with our cardiothoracic and plastic surgery colleagues. We began with a midsternal skin incision followed by a complete 360-degree circumferential dissection of the mid-distal sternum. This left the manubrium and sternal notch intact as the superior aspect of the sternum was clearly uninvolved on imaging studies. A circumferential margin of 3 to 4 cm was removed with resection of the ribs. The central and distal portions of the sternum, including the xiphoid process (Figure 2 and Figure 3), were also completely removed. Chest wall stability was maintained by leaving the uninvolved superior aspect of the sternum intact. A high-grade adenocarcinoma, which involved bone and periosseous soft tissue consistent with a mammary duct primary cancer, was revealed in a final histologic analysis of the specimen. All rib margins were negative, with the carcinoma closely approximating the deep soft-tissue margin of the surgical resection to within 0.1 mm (Figure 4). We had decided preoperatively against placing synthetic mesh or nonautologous tissue into the resulting defect due to the uncertainty of surrounding tissue involvement and the possibility of developing recurrent disease in this area. Thus, the resulting defect measured 13 x 13 cm, and tissue reconstruction was achieved with bilateral pectoralis major muscle advancement flaps brought to the sternal midline, with the vascular pedicle based upon the thoracoacromial artery (Figure 5).

Following a full recovery from her operation, the patient was again placed on anastrazole and leuprolide, and she has since completed a full year of trastuzumab therapy. She tested negative for BRCA1 and BRCA2 genetic mutations. Despite these negative genetic testing results, she wished to undergo a prophylactic mastectomy of the right breast with immediate bilateral reconstruction. In January 2008, she underwent a right breast prophylactic mastectomy, sentinel lymph node mapping of the right axilla using blue dye only, and the immediate placement of tissue expanders. Due to the patient’s prior course of radiation to the left chest wall, a left latissimus dorsi myocutaneous flap was used for reconstruction and bilateral silicone implants were inserted (Figure 6).

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