Recurrent pleomorphic adenoma of the parotid gland: A comparison of radiographic and pathologic tumor burden

PURPOSE

To compare recurrent pleomorphic adenoma tumor burden as detected on magnetic resonance and computerized tomography imaging with postoperative histopathology.

MATERIALS AND METHODS

44 patients were identified at a tertiary medical center between 2000 and 2015. Patients were included if they had viewable preoperative imaging and a postoperative diagnosis of recurrent pleomorphic adenoma. Primary outcomes were differences in the number and size of lesions detected on imaging and pathology.

RESULTS

The size in greatest dimension between pathology and imaging was not significant on aggregate MRI + CT (p = 0.78), MRI (p = 0.41), or CT (p = 0.69). There were more lesions found on pathology compared to both aggregate MRI + CT (p = 0.003) and CT alone (p = 0.014). The number of lesions between MRI and pathology failed to reach significance (p = 0.06). On univariate analysis, the interval between imaging and pathology (recurrent surgery) did not significantly affect the number of lesions detected (p = 0.18). On multivariable analysis, CT as the primary imaging modality and >1 recurrence was independently associated with greater inaccuracy with respect to number of lesions detected (p = 0.006; p = 0.008).

CONCLUSION

The size of the largest lesion on pathology can be accurately determined with imaging. Compared to MRI, CT scans significantly underpredict the number of lesions found on pathology. MRI should be prioritized unless contraindications exist. These findings will help guide imaging choice, preoperative planning, and patient counseling.

Natural history of recurrent pleomorphic adenoma: implications on management

BACKGROUND

Treating recurrent pleomorphic adenoma (RPA) aims to reduce risk of malignant transformation (MT) while avoiding facial nerve injury. Our objective was to systematically investigate this natural history of RPA and address the current rational for its treatment.

METHODS

The follow-up data of two nationwide series of PA was pooled with a focus on risk of MT and analyzed against the literature.

RESULTS

The combined nationwide data (n = 9003 PA patients) showed 3.1% with first recurrence of which 6.2% were malignant. In the literature first RPA rate was >7% at 20 years follow-up. MT occurred in 0% to 7%, and facial nerve damage increased from with each surgery 3% to 16% at first RPA to 18% to 30% at second RPA.

CONCLUSIONS

RPA showed a characteristic course with surgery being unreliable and damage to the facial nerve. The risk of MT was low. This might give flexibility towards a more conservative approach of management.