Desmoid tumor of trapezius muscle: A case report.

Introduction: Desmoid tumors are benign fibrous entities developed from connective tissue, and they result from muscle fascia or aponeurosis. Surgical excision is the main pillar of treatment.

Case Report: A 29-year-old female patient presented with a left postero-lateral cervical swelling that had been evolving for 11 months. Cervical MRI showed a mass at the expense of the trapezium muscle measuring 41 × 68 × 81 mm. A biopsy of the mass was performed, concluding a desmoid tumor. The patient underwent a large resection of the tumor involving the left trapezius muscle. An immunohistochemistry staining was performed, demonstrating cytoplasmic labeling with anti AML antibody, and nuclear labeling of tumor cells with anti-beta-catenin antibody. The case was analyzed by a multidisciplinary committee, and it was decided to follow the patient for surveillance.

Discussion: The localization of desmoid tumors in the trapezius muscle is extremely rare. The main risk of these benign lesions is infiltration of surrounding tissue leading to morbidity and mortality. Recurrence is a main feature of these tumors, even if complete excision has been performed. Unresectable desmoid tumors require medical and non-surgical treatment such as hormone therapy (tamoxifen), and chemotherapy with vinblastine and methotrexate.

Conclusion: Desmoid tumor of trapezius muscle is classified as benign without metastatic power, and the main risk is infiltration of surrounding tissue.