jmc

Let $2n-2$, $2n$, $2n+2$, and $2n+4$ be four consecutive positive even integers. If $(2n-2)+(2n)+(2n+2)+(2n+4)=8n+4=2^2(2n+1)=m^2$ for some positive integer $m$, then $2n+1$ must be an odd perfect square. $2n+1=1^2$ gives $n=0$, which we reject because our integers are positive. $2n+1=3^2$ gives $n=4$, which yields a sum of $8\times 4+4=36$. Thus, the least possible sum is $\boxed{36}$.