Prevalence of Sclerotic Pterygoid Plate in Pretreatment Nasopharyngeal Carcinoma

Abstract

Objectives: The objective of our study was to determine the prevalence of sclerotic pterygoid plate in pretreatment CT of nasopharyngeal carcinoma compared with the control group.

Materials and methods: A total of 51 nasopharyngeal carcinoma patients (37 men, 14 women) with a mean age of 51.94±13 years, and 51 controls (30 men, 21 women) with a mean age, 49.31±15 years were included in this study in a retrospective fashion. All computed tomographic (CT) images were evaluated by two neuroradiologists. Sclerosis of pterygoid plate and other findings included pterygoid plate erosion, adjacent tumor enhancement, and parapharyngeal extension which were assessed. MRI findings were also recorded. The prevalence of pterygoid plate sclerosis was compared using Chi-square statistical tests. Imaging findings were analyzed by binary logistic regression analyses.

Results: The prevalence of pterygoid plate sclerosis in nasopharyngeal carcinoma was 53.9% compared to the control group (16.7%) and the difference was statistically significant (P-value< 0.001). In nasopharyngeal carcinoma, the prevalence of tumor adjacent to the pterygoid plate, parapharyngeal extension and pterygoid plate erosion were 69.6%, 81.4%, 38.2%, respectively. No erosion of pterygoid plate was detected in the control group. The odds of adjacent tumor enhancement and pterygoid plate erosion was 7.29 and 20.56 times higher in the sclerotic pterygoid plate (p-values of 0.019 and 0.000, respectively). MRI was available for four nasopharyngeal carcinoma cases with five sclerotic pterygoid plates, where two showed enhancements. All non-sclerotic pterygoid plates showed no enhancement on MRI.

Conclusion: The prevalence of sclerotic pterygoid plate is significantly higher in patients with nasopharyngeal carcinoma with a considerably higher chance of adjacent tumor enhancement and pterygoid plate erosion.

Keywords: Nasopharyngeal carcinoma; Pretreatment; Sclerosis pterygoid plate; Tumor extension.

Figure 1

Axial Bone Window CT Image of Nasopharyngeal Carcinoma Patient Shows Sclerosis of the Right Pterygoid Process (Arrow)

Figure 2

Axial Soft Tissue Image with Contrast Administration Shows Bilateral Parapharyngeal Extension

Figure 3

Axial CT Images of a Nasopharyngeal Carcinoma Patient (A) Bone window image shows bilateral sclerotic pterygoid plates with erosion (arrow) (B) Soft tissue window image with contrast administration shows adjacent tumor enhancement (arrowhead) and bilateral parapharyngeal extension

Figure 4

(a), (b), (c) and (d) showed CT scan bone window, T1WI, T2FS, and post-contrast T1WI of the same patient. Sclerosis pterygoid plate is observed on the right side on CT, and MRI demonstrates hyposignal on T1WI, hypersignal on T2FS and faint enhancement on post-contrast T1WI. (e)-(h) are the image set of another patient showing similar pattern at the sclerotic left pterygoid plate. The sclerotic right pterygoid plate in this patient shows hyposignal on T1WI, T2FS and no contrast enhancement. (i)-(l) and (m)-(p) are the image sets of another two patients with sclerosis of pterygoid plates on the right and left sides respectively. The sclerotic pterygoid plates in these two patients demonstrate hyposignal on T1WI, T2FS and no contrast enhancement. The two enhanced pterygoid plates are arrowed in (a) and (e).