sorry, this code is untested, but it may just work~

#!/usr/bin/perl -w
use strict;

my $do_i_chomp?;             # off by default
while(<>){                   # read from STDIN
    $do_i_chomp? && chomp;   # chomp if you should
    m/^DESCRIPTION$/ && do{
        !$do_i_chomp?;       # flip chomping on
        print;               # print the DESCRIPTION line
    };
    print;                   # print the line
    m/^ENDDESCRIPTION$/ && do{ 
        print "\n$_";        # print newline, then the ENDDESCRIPTION 
+line
        !$do_i_chomp?;       # flip chomping off
    }; 
}
[download]

`perl script.pl <infile >outfile`

~Particle