Cytomegalovirus (CMV) is a member of the herpes virus family. Complete CMV particles contain double-stranded DNA enclosed in an icosahedral capsid and surrounded by an envelope. CMV infects epithelial cells and lymphocytes. It moves into the nucleus where it can produce intranuclear inclusion.
CMV infections in humans are frequently asymptomatic and many people carry it (up to 80% of adults have antibodies against it). However, a wide spectrum of diseases can occur in the fetus, newborn and immunocompromised individuals; the most serious of which is congential CMV disease.
One method of detecting CMV is direct examination of biopsy specimens using a Hematoxylin-Eosin stain. Infected specimens may contain characteristic large cells with basophilic intranuclear inclusions. The typical nuclear inclusion has the appearance of an “owl’s eye” because it can be surrounded by a clear halo that extends to the nuclear membrane. Even when this characteristic appearance is seen, virologic or serologic confirmation is recommended for diagnosis. CMV infection can occur without the typical cytomegalic cells.
Figure 1 is an H&E stained lung section showing typical owl-eye inclusions. (480X)
Figure 2 is an H&E stain of Cytomegalovirus (CMV) in monocytes in the lung of a patient with AIDS who had disseminated CMV (culture proven). (1,000X oil)