AGGRESSIVE PSAMMOMATOID OSSIFYING FIBROMAS OF THE SINONASAL REGION - A CLINICOPATHOLOGICAL STUDY OF A DISTINCT GROUP OF FIBROOSSEOUS LESIONS

Background. Psammomatoid ossifying fibromas represent a unique subset of fibro-osseous lesions of the sinonasal tract. They have distinctive histomorphologic features and a tendency toward locally aggressive behavior, including invasion and destruction of adjacent anatomic structures. Methods. Seven cases of psammomatoid ossifying fibromas of the sinonasal tract were identified in the files of the Otolaryngic Tumor Registry at the Armed Forces Institute of Pathology, Medical records, including the clinical history, location of the lesions, radiographs, treatment, and follow-up were reviewed in each case. Follow-up information was available in all of the cases. Results. Four of the patients were male and three were female. The patients' ages ranged from 5 to 54 years (median age, 33 years). Symptoms included facial swelling, nasal obstruction, pain, sinusitis, headache, and proptosis. Radiographic studies confirmed the presence of an osseous and/or soft tissue mass varying in appearance from well demarcated without invasion or erosion to invasive with bone erosion and intracranial extension. Sites of involvement included the nasal cavity and all paranasal sinuses, particularly the ethmoid and maxillary sinuses, Often, more than one sinus was involved and extension of disease included involvement of the orbit, nasopharynx, palate, and anterior cranial fossa. The histologic appearance was characterized by the presence of small mineralized (psammomatoid) bodies admired with a cellular stroma with a variable amount of myxomatous material and scattered giant cells. Confusion with other osseous and soft tissue tumors may occur resulting in too limited or too aggressive management. En bloc surgical excision is the treatment of choice and may prove curative. Aggressive behavior with recurrence(s) or invasion into adjacent structures occurred. At the time of this writing, the patients are alive over follow-up periods ranging from 6 months to 7 years. Conclusions. Gnathic and midfacial fibro-osseous proliferations are a diverse group of lesions. A subset of these fibro-osseous lesions with predilection for the sinonasal tract were identified. These lesions are characterized by their distinctive histology, including psammomatoid ossicles and their locally aggressive growth. Complete surgical removal is the treatment of choice.