PMC5789605_01
On CT A the lesion (see arrows) involves the medial end of the clavicle and is purely lytic; the cortex is destroyed and soft tissues are invaded. On axial MRI the signal is isointense on T1-weighted (B), and heterogeneously hyperintense on fat-saturated T2-weighted (C) and after contrast medium injection (D)
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Fig1
Imaging studies (Fig. 1A) revealed a lytic lesion in the medial end of the left clavicle with cortical destruction and soft tissue invasion. The signal was isointense on T1-weighted (Fig. 1B) and heterogeneously hyperintense on fat-saturated T2-weighted MRI (Fig. 1C) and after contrast medium injection (Fig. 1D). 
Gross features A an 8 cm. Lesion of the left clavicle, with soft tissue invasion. Histological features of the lesion, composed of glomerulus-like structures (B), with papillary structures projecting into the lumen, covered by plump "hobnail" endothelial cells (C-E). Immunohistochemical positivity for podoplanin (D2-40) in the neoplastic cells (F)
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Fig2
Grossly, a gray-reddish lesion was present in the clavicle, with infiltration of the soft tissues (Fig. 2A). Histologically, the tumor was composed of multiple vascular channels, with some areas appearing as glomerulus-like structures (Fig. 2B), with papillary projections into the lumen (Fig. 2C-E). Immunohistochemically, the neoplastic cells were positive for podoplanin (D2-40), a lymphatic vessel marker (Fig. 2F), and for endothelial markers (CD31 and ERG).