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 ( = 9) and DWI ( = 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 ( = 6) with peripheral high intensity rim ( = 5) was frequently observed except heterogeneous low and high ( = 1), diffuse low ( = 1), and high ( = 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 ( = 4), and diffuse ( = 1), heterogeneously high signal ( = 1)]. The mean ADC value was 1.148 ~ 0.961 x 10-3 mm/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 ( = 3), and MRI ( = 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.