<prompt> Onion skin appearance is seen in:Chronic osteomyelitisChronic osteomyelitis with proliferative periostitisGarres chronic non-suppurative sclerosing osteitisBoth 2 and 3  <response>: Radiographic pictureClassical onion skin appearance due to cortical layer duplication is seen in both chronic osteomyelitis with proliferative periostitis and Garres chronic non suppurative sclerosing osteitis. 