Abstract A 32-year-old woman developed periosteal reactive change in the second toe of the right foot without any history of trauma. Radiographs showed periosteal reaction at the proximal phalanx of the toe, and magnetic resonance imaging (MRI) revealed a mass surrounding the phalanx as well as soft tissue edema around the bone. These radiological studies indicated non-neoplastic reactive changes accompanied by bone formation such as florid reactive periostitis and bizarre parosteal osteochondromatous proliferation. The symptoms regressed spontaneously in 1 month and no symptoms were seen 2 years after onset. Due to painful swelling and bone formations with the radiological appearance of tumorous lesions, surgical treatment is sometimes selected for these lesions. Because of possibility of occurrence of a spontaneously regressive variant of this disease, this report emphasizes that careful follow-up may be preferable to immediate biopsy of this entity.