A salmon patch is a very common birthmark that is variation of a port-wine stain and can fade with time and disappear.
More Info: Salmon Patches
Tasneem Poonawalla, M.D., Pharm.D; Dermatology Resident, University of Wisconsin; and Dayna Diven, M.D., Clinical Professor; Department of Dermatology, University of Texas Medical Branch. Core Concepts of Pediatrics. (c) 2008.