HSV: look for multinucleated transitional cells with "ground glass" nuclei and large eosinophilic intranuclear inclusions surrounded by a halo (image A) & (image B).
CMV: classically associated with an enlarged nucleus that contains a single irregular cyanophilic (blue-ish) inclusion surrounded by a halo and a thickened nuclear membrane.
Image C (click on the image above)
Image D (click on the image above)
Seen most often in immunocompromised hosts.
Has been associated with interstitial nephritis and obstruction of the ureteral lumen; may be important in renal transplantation.
Viral infection results in scattered "decoy cells", so called because they become very enlarged with huge nuclei and an extremely high N:C ratio (image C).
The enlargement of the nucleus is due to glassy basophilic intranuclear inclusions (resulting in a "smudgy" appearance to the nucleus) (image D).
The nuclear chromatin may appear to be clumped at the edges of the nuclear membrane, which itself is focally interrupted/ disrupted.
Because of their large size and high N:C ratio, "decoy cells" may mimic carcinoma (hence the name "decoy"), but the key to their benign nature is the smooth structureless chromatin (glassy appearance of the nucleus) and the relative paucity of affected cells.