gistfile1.pl

#!/usr/bin/perl
use strict;
use warnings;

my $dictionary = "/usr/share/dict/words";
open DICTIONARY, "<$dictionary" or die "$!";
my $map = {};

while(my $word = <DICTIONARY>){
   chomp $word;
   if(length($word) > 3){
      $word = lc $word;
      my @word = split(//, $word);
      my ($firstLetter, $lastLetter) = @word[0,-1];
      my $key = join '', sort {$a cmp $b} @word;
      $map->{$key}->{$firstLetter}->{$lastLetter}->{$word}++;
   }
}

for my $key (keys (%$map)){
   for my $firstLetter (keys %{$map->{$key}}) {
      for my $lastLetter (keys %{$map->{$key}->{$firstLetter}}) {
         if( scalar( keys %{$map->{$key}->{$firstLetter}->{$lastLetter}} ) > 1){
            print join(",", keys(%{$map->{$key}->{$firstLetter}->{$lastLetter}}));
            print "\n";
         }
      }
   }
}