Tokyo stocks plunged Monday, with the Nikkei index briefly losing over 2 percent, as selling was fueled by concerns over the European economy amid political turmoil and caution over the U.S. economic outlook. The 225-issue Nikkei Stock Average ended down 712.12 points, or 1.83 percent, from Friday at 38,102.44. The broader Topix index finished 46.60 points, or 1.70 percent, lower at 2,700.01. On the top-tier Prime Market, decliners were led by real estate, oil and coal product and mining issues. The U.S. dollar was largely flat mostly in the lower 157 yen range in Tokyo amid few fresh trading …