PMC2817869_01
Axial view of PET-CT scan image demonstrates a large hypermetabolic mass with intense uptake of F18 Levo-DOPA in the posterior mediastinum near the left atrium which is consistent with paraganglioma.
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F1
On PET-CT, a large hyper-metabolic soft tissue mass measuring 4.5 x 2.7 x 3.9 cm in the region of posterior mediastinum near the left atrium was noted (Figure 1, arrow).
Horizontal long axis CMR images demonstrate a round, well defined posterior mediastinal mass with smooth extrinsic compression of left atrial wall which is hypo-intense on breath-hold Steady State Free Precession (SSFP) cine CMR (a, arrow), and shows homogenously high signal on T2-weighted dark blood turbo spin-echo image (b, arrow). T1-weighted inversion recovery gradient-echo myocardial perfusion imaging demonstrates heterogeneous, mostly peripheral, dynamic contrast filling of the mass suggesting vascularity (c, arrow), and T1-weighted, fat-saturated, inversion recovery late gadolinium enhancement image shows peripheral rim enhancement with no evidence of central enhancement suggestive of central tissue necrosis (d, arrow).
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F2
TR: 2.4 ms, temporal resolution: 40.3 ms), the epicenter of the hypo-intense soft tissue mass was noted to be in the posterior mediastinum with no apparent fat plane between the lesion and the posterior wall of the left atrium (Figure 2-a, arrow). The mass caused smooth extrinsic compression of left atrial wall and demonstrated typical low signal on T1-weighted spin-echo (TE: 14 ms, TR: 750 ms) and high signal on T2-weighted dark blood turbo spin-echo (TE: 86 ms, TR: 4000 ms) images (Figure 2-b). During administration of 5 mL of gadopentetate dimeglumine (Magnevist, Berlex Laboratories, Wayne, NJ), T1-weighted inversion recovery gradient-echo myocardial perfusion imaging was performed which demonstrated heterogeneous dynamic contrast filling of the mass (Figure 2-c). T1-weighted, fat-saturated, inversion recovery sequence. This demonstrated peripheral rim enhancement of the mass with central dark signal suggestive of central tissue necrosis (Figure 2-d).
(A) Low power photomicrograph (40x; H&E stain) demonstrates tumor (*) compressing left atrium (LA). (B) The tumor is comprised of nests of fairly uniform cells with moderate eosinophilic, granular cytoplasm (200x; H&E stain). (C) Marked cytologic atypia with pleomorphic nuclei and prominent nucleoli was focally present (400x; H&E stain) in addition to (D) increased number of mitoses (arrows) (400x; H&E stain). (E) Scattered foci of coagulative tumor necrosis (N) were also noted (200x; H&E stain). (F) The tumor exhibited diffuse, strong cytoplasmic positivity for synaptophysin immunostain (400x). (G) S100 immunostain highlights sustentacular cells surrounding nests of tumor cells (400x).
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F3
Histopathologic evaluation indeed confirmed a cardiac paraganglioma (Figure 3).