Multifocal nonosteogenic fibroma: report of a case with ultrastructural findings

The case of a patient in whom multiple nonosteogenic fibromas developed is reported. This condition is very unusual and must be differentiated not only from the multiple lesions that occur in association with well-known entities but also from some occasionally multifocal bone tumors. The lesion is characterized by proliferations of spindle cells disposed in storiform patterns, with numerous scattered multinucleated giant cells. Ultrastructural study revealed that the basic cell of this lesion had fine structural features of both fibroblast and myofibroblast cells.