PARIS, April 26 (Reuters) - French business group Lagardere said on Monday it was reviewing a project to change its corporate form into a joint-stock company. “Discussions are ongoing in this respect between the company and its main shareholders. There can be no certainty as to the outcome of the current discussions,” said Lagardere, whose businesses include Paris Match magazine and airport shops. Vincent Bollore, the top shareholder in Lagardere via his Vivendi group, and LVMH luxury goods boss Bernard Arnault - also a Lagardere investor - have been at the centre of a tussle over the company and its influential media outlets for months. (Reporting by Dominique Vidalon; Editing by Sudip Kar-Gupta)