Kourtney Kardashian shares rare throwback photos to mark sister Kim's 45th birthday

Kourtney Kardashian Barker paid a sweet tribute to her sister Kim Kardashian on her 45th birthday.

Taking to her Instagram handle on Tuesday, the Lemme founder posted a series of rare throwback images of herself with her sister, calling Kim her "best friend."

The carousel begins with a picture of the two of them from what appears to be their teenage years, standing next to each other in matching outfits.

Another image shows the famous sisters making kissy faces as they pose for the camera.

“Best friends forever," Kourtney penned in the caption.

To mark Kim's birthday, her sister Khloé Kardashian also penned a heartfelt birthday note for the Skims founder.

 “Happy Birthday to my sister, my best friend, my forever twin flame in chaos and greatness, @kimkardashian where you go, I go," she penned on her Instagram.

“Every year, I’m in awe of how you continue to evolve. Somehow, you keep leveling up in strength, grace, wisdom, and heart. You’ve always been powerful, but lately it feels like you’ve tapped into an even deeper layer of yourself, calmer yet more unstoppable, grounded yet still dreaming bigger than ever,” she added.