Review of tonsillar lymphoma in pediatric patients from the pediatric oncology group: what can be learned about some indications for microscopic examination?
Data says don't. There have been a number of studies (2005 pog study and more recently in 2011 and 2012) to suggest that always doing microscopic examination on routine tonsillectomies is not cost effective. If someone has a index of suspicion (clinical or asymmetric enlargement), then it is warranted. It has been estimated that not doing this automatically could save ~$35 million per year.
Always look. In virtually all situations that I am aware of (usa physician), a pathologist always looks microscopically at any tissue removed surgically.