Proliferative myositis is a rare pseudosarcomatous inflammatory process. Radiological diagnosis of self-limiting proliferative myositis helps direct appropriate clinical management and avoiding unnecessary surgical excision. We present the ultrasonography, computed tomography, and magnetic resonance imaging findings in a case of proliferative myositis. In this case, malignancy was suspected, and complete excision was performed. A checkerboard-like pattern, a characteristic sonographic and pathological finding of proliferative myositis, was demonstrated by computed tomography in our patient; to the best of our knowledge, this is the first such case in the literature.