In a medium skillet, heat the olive oil over medium-high heat. Add the shrimp, scallion whites and Cajun seasoning and cook, stirring, until the shrimp is opaque, about 2 minutes. Transfer to a bowl and refrigerate.
Core the tomatoes and cut each into 8 sections, leaving the sections connected at the bottom. Divide the lettuce among 4 serving plates and top each with a tomato, splaying out the sections slightly.
Add the scallion greens, mayonnaise, celery and Worcestershire sauce to the shrimp mixture and toss. Fill each tomato with the shrimp salad and top with some egg.