Differentiation malignant from benign parotid tumors in children with diffusion-weighted MR imaging

Pediatric primary salivary gland tumors

OBJECTIVES

To characterize the presentation and treatment of children presenting with primary salivary gland neoplasms.

METHODS

A retrospective review of primary salivary tumor patients presenting to Children's Hospital Colorado between January 2000 and August 2020.

RESULTS

Fifty children were identified with primary salivary gland tumors, comprising of 39 (78 %) benign and 11 (22 %) malignant lesions. Pleomorphic adenoma was the most common benign tumor (36/39, 92 %), while acinic cell carcinoma was the most common malignancy (7/11, 64 %). The parotid gland was the most common site, followed by the submandibular gland (66 % vs. 34 %). No tumors were found in the sublingual glands. Benign neoplasms accounted for 70 % of parotid lesions and 94 % of submandibular tumors. No significant differences in age (13.6 years, SD 4 vs. 13.0 years, SD 4.3) were noted between patients with benign and malignant disease, but tumors in females were more frequently malignant (M:F 1:1.3 vs. 1:2.7 for benign and malignant tumors, respectively). Neck dissection and/or facial nerve sacrifice were required in 27 % (3/11) and 9.1 % (1/11) of malignancies, respectively. Local recurrence was observed in 7.7 % (3/39) of benign cases and 9.1 % (1/11) of malignant cases. No salivary malignancies required chemotherapy, though one patient with neurofibromatosis received imatinib prior to resection. Two patients with locoregional malignancy received adjunctive radiation. The average duration of follow up for benign and malignant disease were 12.6 ± 25 and 45.1 ± 32 months, respectively.

CONCLUSIONS

This study presents one of the larger single institutional experiences of pediatric primary salivary neoplasms in the past 20 years, identifying pleomorphic adenoma and acinic cell carcinoma as the most common benign and malignant etiologies, respectively. While this review found most neoplasms presented as a localized mass effectively managed with conservative surgical resection, aggressive tumors required multidisciplinary care.

The radiologic (CT/MRI)-pathological correlations of the salivary duct carcinoma (SDC) with hyaline degeneration and peripheral nerve invasion

OBJECTIVES

Salivary duct carcinoma is an aggressive tumour commonly showing local invasion and/or nerve palsy. However, their CT/MRI findings, especially, regarding T2WI, and the diffusion-weighted-image (DWI), were not well known. In this study, we correlated the CT/MRI appearance and the pathological findings containing the nerve invasion cases such as a facial nerve.

METHODS

We reviewed 14 cases of SDC (parotid = 11, submandibular = 2, minor salivary gland = 1) pathologically proven peripheral nerve involvement. Their CT findings of all patient including dynamic contrast-enhancement study､MRI (n = 9) and DWI (n = 6) were also analyzed with histopathological correlation.

RESULTS

On contrast-enhanced CT, the solid component was moderately enhanced. On MRI, T2WI central low signal core (n = 6) with peripheral high intensity rim (n = 5) was frequently observed except heterogeneous low and high (n = 1), diffuse low (n = 1), and high (n = 1) signal cases. The hyaline degenerative area located in the tumour core was poorly enhanced. Eleven tumours had an ill-defined margin, reflecting invasive tumour growth. On DWI, they showed high signal [the central low and peripherally high (n = 4), and diffuse (n = 1), heterogeneously high signal (n = 1)]. The mean ADC value was 1.148 ~ 0.961 x 10-3 mm²/s. With pathological correlation, the central low signal area on T2WI reflected hyaline degeneration. The sites of gross nerve involvement were revealed as tubular or branching structures on CE-CT (n = 3), and MRI (n = 1).

CONCLUSIONS

(1) We frequently observed a central low signal area on T2WI/DWI in SDC. With histopathological correlation, it corresponded to the central hyaline degeneration with the peripheral viable tumour. 2) The gross nerve involvement might be detected as a strongly enhancement structure.