Drain tuna, reserving 1 tsp oil, and place in medium-sized bowl.
Add oil from tuna, lemon juice, parsley, egg, panko, and black pepper to bowl. Mix well.
Form 4 burger-sized patties with tuna mixture.
Place in refrigerator for about an hour.
Heat large skillet with 2 T olive oil over medium heat.
When skillet is hot, add tuna patties and cook for about 4 minutes on each side, until browned.
While tuna burgers are cooking, heat a second skillet or grill pan over medium-high heat. Add pineapple to pan and cook for about 8 minutes, stirring often, until pineapple begins to brown.
Top tuna burgers with lemon mayo and grilled pineapple and serve on toasted whole wheat buns with lettuce.