A case of primary chronic sclerosing osteomyelitis of the fibula in a 14-year-old is described. This rare condition can be difficult to differentiate from a bone tumor. Its pathogenesis is controversial, although the prevalent hypothesis involves chronic osteomyelitis developing after an unrecognized phase of acute infection. The existence of primary chronic sclerosing osteomyelitis as a disease in its own right has been challenged. Recently, primary chronic sclerosing osteomyelitis has been interpreted as a localized or monofocal variant of multifocal recurrent chronic osteitis or of the bone abnormalities associated with seronegative spondyloarthropathies (SAPHO syndrome).