“…High mitotic activity was reported in 18 tumors [ 3 , 4 , 10 , 12 , 16 , 18 , 19 , 22 , 24 , 25 , 31 , 32 , 35 , 37 , 40 - 42 ], and in four of them, more than 20 mitoses were observed per 10 high-power fields [ 4 , 22 , 35 , 40 ]. Vascular invasion was reported in four cases [ 22 , 32 , 36 ]. Other histologic features were spindle cell proliferation (14 cases) [ 16 , 19 , 22 , 23 , 26 , 27 , 29 , 30 , 32 , 33 , 35 , 37 , 41 , 42 ], presence of signet ring cells (one case) [ 4 ], anaplasia (two cases) [ 23 , 47 ], and pseudoangiosarcomatous features (one case) [ 35 ].…”