Subperiosteal hematoma. Another scintigraphic 'doughnut'

The 'doughnut' sign has been described frequently in brain and skeletal scintigraphy, but not previously in a subperiosteal hematoma associated with neurofibromatosis and focal gigantism. The primary cause and evolution of this skeletal 'doughnut' sign is discussed; a brief review of other causes of this scintigraphic finding also is given.