Ossifying fibroma of the ethmoid sinus.An ossifying ossifying /os·si·fy·ing/ (os´i-fi?ing) changing or developing into bone. ossifying changing or developing into bone. fibroma fibroma /fi·bro·ma/ (fi-bro´mah) pl. fibromas, fibro´mata a tumor composed mainly of fibrous or fully developed connective tissue. is a benign lesion that may involve the paranasal sinuses. Most of these fibro-osseous masses appear clinically in adults between 20 and 40 years of age; they have a predilection to males (5:1). (1) A 47-year-old man presented with a history of chronic sinusitis, rhinorrhea, and nasal obstruction. Computed tomography (CT) revealed the presence of a well-marginated expansile mass with an epicenter in the right ethmoid sinus (figure). The mass extended into the right orbit and anterior cranial fossa. [FIGURE OMITTED] Fibrous dysplasias and ossifying fibromas are considered to be two different entities, but they are not always distinguishable on histologic evaluation; both are classified as benign fibro-osseous lesions. (1-3) The most common signs and symptoms (e.g., nasal obstruction, rhinorrhea, pain, and facial deformity) are consistent with a slow expansile process. Other symptoms may include exophthalmus, diplopia diplopia /di·plo·pia/ (di-plo´pe-ah) the perception of two images of a single object. binocular diplopia , and loss of visual acuity. (1,3) Like fibrous dysplasias, ossifying fibromas are occasionally detected as an incidental finding. The diagnosis is made by CT and histology. Magnetic resonance imaging magnetic resonance imaging (MRI), noninvasive diagnostic technique that uses nuclear magnetic resonance to produce cross-sectional images of organs and other internal body structures. is usually nonspecific, and it can even be misleading in light of the lack of good demonstrations of bone and fibrous tissue. (2) Histologically, an ossifying fibroma is a densely cellular, well-defined fibrous tumor that begins ossifying at the periphery. Again, it may be histologically indistinguishable from an active form of fibrous dysplasia. (1) In addition to fibrous dysplasia, the differential diagnosis on imaging should include osteoma osteoma /os·te·o·ma/ (os?te-o´mah) a benign, slow-growing tumor composed of well-differentiated, densely sclerotic, compact bone, occurring particularly in the skull and facial bones. , cementoma, and osteosarcoma osteosarcoma /os·teo·sar·co·ma/ (os?te-o-sahr-ko´mah) a malignant primary neoplasm of bone composed of a malignant connective tissue stroma with evidence of malignant osteoid, bone, or cartilage formation; it is subclassified as . (1) References (1.) Harnsberger HR, Wiggins RH III Hudgins PA, et al. Ossifying fibroma, sinus. In: Harnsberger HR, Wiggins RH III, Hudgins PA, et al, eds. Diagnostic Imaging: Head and Neck. Salt Lake City: Amirsys, 2004. (2.) Kendi AT, Kara S. Ahinok D, Keskil S. Sinonasal ossifying fibroma with fluid-fluid levels on MR images. AJNR Am J Neuroradiol 2003;24:1639-41. (3.) Alawi F. Benign fibro-osseous diseases of the maxillofacial bones. A review and differential diagnosis. Am J Clin Pathol2002:118(suppl): S50-70. Enrique Palacios, MD, FACR FACR abbr. Fellow of the American College of Radiologists From the Department of Radiology, Louisiana State University Health Sciences Center, New Orleans. |
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