A subcutaneous tumor accompanied by tenderness has a myriad of differential diagnoses. Indeed, using physical findings alone to achieve a diagnosis is often challenging. In this study, we focused on schwannomas and angioleiomyomas, which usually develop as hard subcutaneous tumors and are often associated with tenderness. We aimed to determine significant differentiating features between the tumor types, using ultrasonography. We compared clinical findings and ultrasonographic imaging and calculated the statistical significance for each item. In total, we analyzed 11 schwannomas and 13 angioleiomyomas of the extremities, trunk and head. There was no significant difference in patient characteristics or clinical findings. Meanwhile, the mean maximum diameter (P = 0.002), localization (P = 0.04) and entering or exiting nerves (P = 0.01) were significantly different according to ultrasonography findings. Thus, ultrasonography provides excellent information for the initial assessment of a slow-growing, painful, subcutaneous soft tissue mass. According to our study, it is difficult to identify a single, differentiating feature between angioleiomyoma and schwannoma on ultrasonography, but including multiple findings during the work-up can facilitate differential diagnosis.