Case report: Trapezius Fibromatosis in the Elderly – An Extremely Rare Tumor

Summary

Desmoid-type fibromatosis typically manifests as a deeply seated but poorly circumscribed soft-tissue mass. Herein, we present the case of a 78-year-old man who developed a gradually progressive painless swelling over the right side of the neck over a period of 6 months. The patient was planned for a magnetic resonance imaging scan which showed ill-defined lobulated mass in the right trapezius of size 4 × 7 × 5.4 cm, which was heterogeneous in T2, isointense in T1, multiple ovoid calcifications, and was suspected with cysticercosis or fibroma. Open biopsy was done a week later which was suggestive of fibromatosis. The patient underwent definitive resection of the tumor 1 week later and the tumor was found to be restricted to the muscular plane. Histology was consistent with fibromatosis, the specimen being positive for vimentin, beta-catenin, and smooth muscle actin. The patient was on serial follow-ups and the last follow-up, 3 year later did not show any signs of recurrence of the tumor.