Syndication question

I am using extern.php to get the ten latest topics listed on a page and it is working without any problems... However, I wonder if it is possible to colour one of the links if the topic contains a certain word?

Example
Topic 1 Banana
Topic 2 Monkey
Topic 3 Tree

And in this example I want all topics that contains the word ´tree´ to be coloured green in the list but the rest to have the standard colour.