[Benign sub-periosteal osteoblastoma of the nasal cavity. histological and ultrastructural study of a case].

A case of periosteal benign osteoblastoma arising in the left nasal cavity is presented. The tumor develops on the surface of the middle turbinate without evidence of bone destruction. It has been locally excised and has not recurred in 3 1/2 years. The histological aspect is identical to that of the other cases of genuine osteoblastoma. The ultrastructure (the first of a periosteal osteoblastoma) is described. The osteoblasts resemble normal osteoblasts with a few exceptions: irregular nuclei, abundance of well-developed rough-surfaced endoplasmic reticulum and numerous fine filaments. The osteocytes and osteoclasts basically resemble their normal counterparts. The final diagnosis of benign osteoblastoma rests at the light microscopy level. The differential diagnosis are reviewed. Distinguishing histologic and ultrastructural characteristics between this tumor and other benign osteoblastic tumors are discussed.