A REEVALUATION OF IMAGING CRITERIA TO ASSESS AGGRESSIVE MASTICATOR SPACE TUMORS

Purpose. To evaluate the correlation between the gross imaging evidenc e oi an aggressive masticator space (MS) tumor and the presence of suc h a MS malignancy. Materials and Methods: Thirty patients were identif ied retrospectively who had a malignancy that either arose in or metas tasized to the MS, had pathologic verification of the diagnosis, and h ad magnetic resonance (MR) and/or computed tomographic (CT) images. Sp ecifically evaluated was the presence or absence of gross imaging evid ence of mandibular erosion and the integrity of the medial MS fascia a s evaluated by a smooth margin between this fascia and the parapharyng eal space fat. Results. Of the 30 tumors, 28 were high-grade malignanc ies and 2 were histiocytoses. Of these, 5 had mandibular erosion and v iolation of the MS fascia, 19 had bone erosion with an intact fascia, 4 had neither bone erosion nor fascial violation (3 of these patients were under the age of 20 years), and 2 had fascial violation with no b one erosion. Conclusions. In 76.7% of patients with a malignancy arisi ng in the MS, on imaging the medial MS fascia was grossly intact. Ther e were 4 patients with MS malignancy and neither violation of the medi al MS fascia nor mandibular bone erosion. Thus, these imaging findings may not be good criteria to evaluate the presence of a high-grade MS malignancy, especially ii the patient is under the age of 20 years, in which age group MS sarcomas are more likely to arise. (C) 1997 John W iley & Sons, Inc.