Birthday celebrations can differ substantially based on culture.
In America, when it is your birthday, you generally go out to eat and celebrate with family and friends. Your friends typically take you out to dinner or for drinks and treat.
While Italians also go out with friends for their birthdays, one major difference is who pays for the bill. In Italy, you make the restaurant arrangements and invite your friends out for dinner. In Italy, it goes without saying that you will be paying for the bill. Similarly, when it is your birthday at work, the expectation is that you will be bringing in sweets.
Nevertheless, Italians do not show up empty-handed and always bring the birthday girl or boy a gift. However, another major difference in birthday celebrations in Italy compared to America is that in Italy, giving a card along with a gift is not custom or expected the way it is in America!