German corpse 'may be Luxemburg'
A pathologist at Berlin's Charite hospital told Der Spiegel magazine the headless corpse bore "striking similarities" to the left-wing icon.
Ms Luxemburg was murdered by right-wing paramilitaries in 1919 at the age of 47 and thrown in an icy canal.
Months later, a body thought to have been hers was retrieved and buried.
The grave, in Berlin's Freidrichsfelde cemetery, has since become a place of pilgrimage for communists, feminists and left-wing activists.
But Michael Tsokos, head of the hospital's Institute of Legal Medicine and Forensics Science department, told Der Spiegel that he doubted the identity of the corpse that was buried there.
He pointed to several inconsistencies in the post mortem examination his predecessors at the hospital had carried out on the interred body, which made him question its conclusions.