Malignant parotid tumors in patients previously treated for childhood cancer: clinical and imaging findings in eight cases.

Abstract

The purpose of this study was to describe the clinical and imaging characteristics of malignant neoplasms of the parotid gland in patients who had been successfully treated for childhood cancer. Eight cases of parotid carcinoma were identified among survivors of primary childhood cancer treated at two centers. Medical records and imaging studies were reviewed to identify the frequency of second parotid tumors, to assess possible risk factors for their development, and to identify any specific MR or CT features of these tumors. Parotid tumors (mucoepidermoid carcinoma in seven cases and acinar cell carcinoma in one) were diagnosed a median of 9 years (range, 4-16 years) after diagnosis of the initial cancer. These tumors represented 6% of the second cancers diagnosed at one center, whereas salivary gland malignant neoplasms accounted for only 0.08% of primary cancers diagnosed during the same period. The patients ranged from 1 month to 14 years old at the time of initial diagnosis of acute leukemia (n = 7) or neuroblastoma (n = 1). All patients had received multiagent chemotherapy for their initial cancer, and six had received radiation to the head and/or neck. At diagnosis, the parotid tumors were painless, enlarging, periauricular masses without associated facial nerve palsy. Preoperative CT, performed in three cases, showed a solid enhancing parotid soft-tissue mass that was isodense with muscle. MR imaging in two cases showed inhomogeneously enhancing parotid masses. One was isointense with the contralateral parotid gland on T1- and T2-weighted images and hyperintense on contrast-enhanced T1-weighted images; the other was hypointense on T1-weighted images and showed inhomogeneous enhancement that was more intense than in the normal parotid gland. The borders were poorly defined in both these cases. Malignant parotid gland tumors are rare in the first two decades of life but may occur more often among patients who have previously received radiation therapy and/or chemotherapy. The CT and MR appearances of these lesions are variable.