Questo puo' essere un punto di partenza.

Codice PHP:
<? ob_start() ?>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>
<head>
<title>Untitled</title>
</head>
<body>


<textarea name="ctl00$cphMain$txtTranslationResult" rows="6" cols="35" id="ctl00_cphMain_txtTranslationResult">
plutocaiowDFKqfdn
dfqsfdmlqsff;pmqsf^pqsfsfpqspf^qpsfpqpsfpq 
</textarea> 

</body>
</html>
<?php
$content = ob_get_contents();
ob_end_clean();
$search_regex = "|<textarea[^>]+>(.*)</textarea>|Umsi";

$result = preg_match($search_regex,$content,$match); 
$match[1] = str_replace("","",$match[1]); 

print $match[1];

//print $content;
 ?>