my %accession =
(
    '1223455' => [ { item1 => 'abdkek',   item2 => 'akdjeg' },
                   { item1 => 'ksitjls',  item2 => 'jsoirl' },
                   { item1 => 'lsiet',    item2 => 'oliut'  } ],
    '2874824' => [ { item1 => 'lsiugl',   item2 => 'potpsgj' },
	               { item1 => 'postis',   item2 => 'potltids' } ],
    '1375080' => [ ],
    '0875709' => [ { item1 => 'llskgjo',  item2 => 'ooiwuto' } ],
    '9876653' => [ { item1 => 'lsgjgdlk', item2 => 'ldkgjldj' } ]
);

my ($accession, $item1, $item2);

foreach $accession (sort keys %accession)
{
    #....

    if (not scalar @{$accession{$accession}})  # no items 
    {
        $item1 = $item2 = '';
        write;
        next;
    }

    foreach my $itemset (@{$accession{$accession}})
    {
        # Do whatever you want to set $item1, $item2

        $item1 = $itemset->{item1};
        $item2 = $itemset->{item2};
        write;
        $accession = '';  # blank for subsequent prints
    }
}

format STDOUT_TOP =
Accession      item1       item2
.

format STDOUT =
@<<<<<<<<<<<<< @<<<<<<<<<< @<<<<<<<<<
$accession,    $item1,     $item2
.