Subtotal Sternectomy with Reconstruction for Metastatic Thyroid Carcinoma

Abstract

Introduction: Approximately 4% of thyroid cancer patients present with bone metastases.1 Only 18.3% of those patients present with metastases to the thorax (rib and sternum).2,3 Bony metastases often correlate with increased morbidity and decreased overall survival.4 Therefore, multimodality treatment including surgical resection is often warranted. This study includes a video demonstration of a subtotal sternectomy for metastatic differentiated thyroid carcinoma and reconstruction using a composite methylmethacrylate and Prolene mesh covered with a pedicled latissimus dorsi flap. Materials and Methods: A 70-year-old woman presented with a 6.7-cm lesion involving the manubrium and sternal body. Informed consent was obtained. Her medical history included bilateral mastectomies with implant reconstruction for ductal carcinoma (2014) and a right thyroid lobectomy for a presumptive benign thyroid adenoma (2015). The right thyroid was removed with pathology analysis demonstrating recurrent well-differentiated thyroid carcinoma with features of both follicular thyroid carcinoma and follicular variant papillary thyroid carcinoma. In addition to the changes to the sternum, imaging showed a 1.4-cm nodular enhancing lesion in the right hemithyroidectomy bed. On positron emission tomography/CT, the sternal mass was intensely fluorodeoxyglucose avid. There was no evidence of additional distant metastases. Sternal biopsy demonstrated BRAF V600E positive metastatic follicular thyroid cancer. Results: This case was discussed at multidisciplinary tumor board, and consensus was for upfront surgical resection with likely adjuvant therapy. External beam radiation and radioactive iodine (RAI) therapy were recommended with possible administration of BRAF V600E inhibitors in the event of the development of an unresectable recurrence or progressive distant metastases. The patient underwent a left completion thyroidectomy to facilitate RAI, a right thyroidectomy bed mass excision, and a subtotal sternectomy extending below the fourth rib. Posterior margins of the sternal mass were positive, and the anterior margin was at risk with a clearance of 1 mm. The remainder of the margins was clear. Reconstruction was performed with methylmethacrylate and Prolene mesh, and a pedicled latissimus dorsi flap was used to cover the composite reconstruction. The patient began adjuvant proton beam radiation therapy to the sternum and anterior chest wall ~4 months later, with plans to undergo RAI. Overall, patients do well after a latissimus dorsi pedicled flap with minimal morbidity. A systematic review of donor site morbidity after latissimus dorsi flap (both pedicled and free flap) including 729 cases demonstrated little difficulty in daily activities after surgery but significant difficulty in participating in sports and art activities.5 Eight of 12 articles reported some shoulder strength weakness over time—shoulder extension, adduction, and internal rotation were commonly involved. Our use of Prolene mesh folded over methylmethacrylate with overlying latissimus dorsi muscle flap created adequate structural support that she was not restricted from performing any activities in the long term. However, immediately postoperatively, she was placed on sternal precautions: limiting arm motions overhead and to the side, as well as restricting strenuous arm exercises. Conclusions: This video demonstrates a subtotal sternectomy and reconstruction with methylmethacrylate, Prolene mesh, and a pedicled latissimus dorsi flap in a patient with metastatic differentiated thyroid carcinoma. Authors' Contributions: D.K. contributed to investigation, project administration, observation, and writing—original draft. J.Y. and V.S. were involved in investigation, project administration, observation, and writing—review and editing. S.R. carried out conceptualization, supervision, observation, and writing—original draft. D.N. took charge of supervision, investigation, and resources. R.F. was involved in supervision, investigation, and resources. M.U. was in charge of conceptualization, methodology, supervision, investigation, resources, and writing—review and editing. No competing financial interests exist. Runtime of video: 7 mins 26 secs This study was presented at the World Congress on Thyroid Cancer on June 16th, 2023, in London as a video abstract presentation.