Massachusetts Schools Pension Plan for non teacher employees

In MA, the pension plan allows participants to retire after 10 years and attaining age 55.

If a participant takes a leave of absence due to medical reasons from April through August, can this participant be denied a pension if he decides not to go back to work.

The participant completed 10 years of service and age 55 during this time period. 

You would be better off asking such a plan specific question of the plan.   Most state plans I am familiar with, which is  a pretty small number, all have people you can call or e-mail with such questions. 

If the plan you ask about is Massachusetts Teachers' Retirement System (which also covers some non-teacher workers), here's a starting point:

https://mtrs.state.ma.us/