INTRODUCTION: Vascular leiomyoma is a rare tumour of smooth muscle origin. It has been reported in many anatomical sites, but it usually affects limbs. It’s recurrence rate is slow but it’s quite difficult to make diagnosis. CASE REPORT: The study describes the case of a 53-year-old man, with a subcutaneous, large vascular leiomyoma of the right clavicular region. The patient had a painful, slow-growing mass, measuring more than 20 mm. The mass had a relatively homogeneous, hypoechoic-echo texture, with a small amount of posterior acoustic enhancement. No diagnosis was made and the patient underwent surgery for a suspected leyomioma. After surgery a hard, round-shaped tumor, measuring approximately 43X32 mm of diameter was found with histological features of leyomioma. DISCUSSION: The case has an unusual clinical presentation, for the uncommon localization and size of the mass. US imaging and histopathologic features are reported. The rarity of vascular leiomyoma makes diagnosis difficult and frequently delayed. Differential diagnosis includes infected sebaceous cists, glomus tumors, hemangiomas, angiolipomas, ganglions, and traumatic neuromas. CONCLUSIONS: This report highlights that leiomyoma, even of large dimension, must be included in the differential diagnosis of painful, subcutaneous masses.