the keyword lines do not contain tabs, right? then:

my @fields;
my $i = 0;
while ( my $line = <$FILE> ) {
   chomp $line; 
   if ( $line =~ /\t/ ) {

       if ($i > 0 ) {
       # do smth with last @fields array 
       }   
       @fields = split "\t", $line;
       $i++; 
   }
   else {
       push @fields, $line;

   }
}
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UPDATE: @fields contains the last line after finishing the while loop.