Vascular leiomyoma presenting as medial joint line pain of the knee

We present the case of a 27-year-old woman with a subcutaneous vascular leiomyoma occurring around the knee. The patient presented with a several-year history of medial-sided knee pain with an unknown etiology. The clinical presentation, magnetic resonance imaging, and histopathologic features are reported, and the literature pertaining to the clinicopathologic characteristics is reviewed. By including vascular leiomyomas in the differential of painful lower extremity subcutaneous masses, an early accurate diagnosis is possible.