This may makes things more complicated than you need, but I should point out that most CSV dumps use quotation marks to escape strings that have commas in them. This is something to watch for: some,comma-delniated,"file with a, comma",in the data

You might take a look at Text::CSV, you could do something like: (untested)

use Text::CSV;
my $csv = Text::CSV->new();
while (<>) {
  $csv->parse($_);
  print join("\t", $csv->fields()); 
}
[download]

That's pretty simplistic, and won't handle tabs in the data, but you get the idea.