unable to do header check for content-type in nginx

This below config is not working . $http_Content-Type = "multipart/form-data; block is not getting executed . Can you some help out.

server {
      listen 8080;
      location /abc {

  if ($request_method = POST) {
    set $test  P;
  }

  if ($http_Content-Type = "multipart/form-data;" ) {
    set $test  "${test}C";
  }

  if ($test = PC) {
   proxy_pass http://upstream;
  }
}
}