Non-epithelial tumors of the nasal cavity, paranasal sinuses and nasopharynx: a clinico-pathologic study XI. fibrous histiocytomas.

As part of our review of non-epithelial tumors involving the nasal cavity, paranasal sinuses, and nasopharynx, nine fibrous histiocytomas (FH) are reported. FH probably are derived from undifferentiated mesenchymal stem cells that have the ability to differentiate into two different pathways, one fibroblastic and the other histiocytic. The proportion of these two different elements varies greatly in different lesions. The cell population ranges from cytologically benign (small bland nuclei and no mitoses) to overtly malignant (marked anaplasia and numerous mitoses). Based on our cases and on 12 previously reported tumors, FH involving the upper respiratory passages may cause clinical problems similar to those produced by other soft tissue neoplasms affecting this area, (nasal obstruction, a mass or swelling in the involved area, epistaxis, loosening of teeth, or facial pain). Physical examination may show a mass projecting into the nasal, sinus, or oral civity; facial asymmetry; proptosis; or a periorbital mass. Radiographic studies may demonstrate sinus opacification or cloudiness, a mass, or bone destruction. Treatment has included polypectomy, wide local excision, partial maxillectomy, or radical maxillectomy, depending on the size and extent of the lesion. When involving the upper respiratory passages, FH, if incompletely excised, may recur locally, requiring a more extensive resection. A minority of these tumors have metastasized via lymphatic and/or venous channels. Histologic features appear to correlate with clinical course.