hello,
I have got a LC 4 original Cassina, there are the marks on the tubolar chrome frame and on the black base, the serial number is 19 144.
the particularity is that is bicolors and bimaterial, in fact the pillow and the footrest are made of black leather, while the mat is made by white fabric sewed at the end with the footrest, i didn't find anything on the web about this model.
I suppose that coul be a limited edition for Charlotte Perriand because the colors can remember also the new model LC4 CP.
Waiting your opinion.
thank you
Luca 
<img class="wpforo-default-image-a
Have you tried contacting Cassina directly? They are still around and are in the best position to answer your question.
http://www.cassina.com/en/contacts/cassina
If you need any help, please contact us at – info@designaddict.com