Looks to be a rare and isolated case in chicks of 25 days. Oviduct infection is becoming very common in layers and breeder females which can be due to Infectious bronchitis specially of Qx type complicated with E.Coli infection. This also can be an ascending infection when females are insemination and no sterile precautions are taken. MYCOPLASMA is another infection which can spread from abdominal air sacs. Learned colleagues may through more light on causes and prevention of oviduct infection in layers and breeder females.
I have seen many cases of cystic oviduct while conducting postmortem of broiler birds. The fluid contained in the cyst may be clear, translucent or contain some flecks. If E. coli gets access, it may attain appearance of salpingitis.