Infectious disease pathology.

The anatomic pathologist performs an important role in the diagnosis or exclusion of infectious diseases. The morphologic interpretation of biopsies and cytologic preparations allows for the definitive establishment or exclusion of a wide variety of diseases. Once the pathologist has determined that a disease is likely to be due to an infection and has characterized the inflammatory response, associated microorganisms or viral-associated cytopathic effects should be recorded. Although some microorganisms or their cytopathic effects may be clearly visible on routine hematoxylin and eosin-stained sections, additional histochemical stains are often needed for their complete characterization. Highly specific molecular techniques, such as immunohistochemistry, in situ hybridization, and nucleic acid amplification, may be needed in certain instances to establish the diagnosis of infection. Through appropriate morphologic diagnoses and interlaboratory communication and collaboration, the anatomic pathologist contributes greatly to the diagnosis and treatment of infectious diseases.