We have received a request from an employee for reimbursement of 1993 tuition expenses. What are the tax and/or administrative issues that we should be considering in deciding whether or not to grant this request?

There are two basic Code sections - Sec. 127 for educational assistance plans (undergraduate education only; need not have connection to employee's job/career; reimbursement limit of $5,250 per calendar year)and an educational institution's reimbursement for tuition of employees and their dependents, under Code Sec. 117(d).
So the answer depends upon whether you are a school or university, or not.