Concatenate and delete duplicates, again

I'm trying to concatenate and delete duplicates (across columns) within Excel 2007 and am having a tough time writing a macro for this. Essentially, my data looks like the 4 left columns and I want to add another column that concatenates the unique sizes

Size 1 Size 2 Size 3 Size 4 Overall Size
1 2 1 1;2
1 1 1/4 1;1 1/4
1 2 3 4 1;2;3;4
1 1 1 1 1

Maybe this is easier than I'm making it out to be, but at over 10,000 lines, I just can't go through this and manually delete the duplicates anymore.