Primary diaphragmatic schwannoma with a typical target appearance: correlation of CT and MR imagings and histologic findings.

A rare case of benign diaphragmatic schwannoma in a 38-year-old female is reported. Precontrast computed tomography (CT) showed an encapsulated well-defined round homogeneous tumor with central calcification, measuring approximately 5 cm in diameter, arising from the left diaphragm. Contrast-enhanced CT and gadolinium-enhanced T1-weighted magnetic resonance (MR) imaging showed focal enhancement in the central portion of the tumor. The tumor showed a typical target appearance of increased peripheral signal intensity and decreased central signal intensity on unenhanced T2-weighted images. Pathological examination of resected specimens of the tumor showed two zonal histological components: a hypercellular portion of spindle cells with nuclear palisading (Antoni A tissue) and a hypocellular portion of cells with cystic degeneration, together with focal calcification and hemangeomatous vascular changes (Antoni B tissue). We consider the radiological characteristics of diaphragmatic schwannoma on CT and MR imagings to represent the geographic difference between the histologic zones of the tumor.