De acordo com a este link , lança arquivos PDF dentro do navegador.
With the Adobe PDF Link Helper (Reader Helper) - an Adobe Acrobat Reader browser add-on - you can view PDF files directly in Internet Explorer. When enabled, PDF files from websites launch automatically in your web browser. Enable/Disable the Adobe PDF Link Helper using the add-on management console in your browser: in Internet Explorer's Tools menu, choose Manage Add-ons/Toolbars and Extensions, then choose Adobe PDF Link Helper and click on the Enable or Disable button at the bottom right of the window.