We consider two loop sunset diagrams with two
mass scales m and M at the threshold and pseudotreshold
that cannot be treated by earlier published formula.
The complete reduction to master integrals
is given. The master integrals are evaluated as series in
ratio m/M and in epsilon with the help of differential equation method.
The rules of asymptotic expansion in the case when q^2 is
at the (pseudo)threshold are given.
