Fine-needle aspiration and surgical pathology of infectious lesions. Morphologic features and the role of the clinical microbiology laboratory for rapid diagnosis

Abstract

There has been a renewed interest in the use of imprint smears at the time of frozen section in surgical pathology and FNA biopsy for the diagnosis of infectious disease because of the increasing need for rapid diagnosis of opportunistic infections in immunocompromised patients. Moreover, the use of FNA biopsy for the evaluation of superficial and deep masses has become more widespread. The critical step in the FNA biopsy and in evaluation of imprint smears from surgical specimens is immediate interpretation of the slides that have been stained by rapid methods as the Diff-Quik technique. This quick interpretation can identify as infectious case that may need ancillary studies such as a separate pass or more tissue for microbiologic examination and special stains on the aspirated smears, sections, or cell block. An infectious case may be suspected when the basic cytologic inflammatory patterns are identified including acute inflammation, chronic inflammation, granulomatous inflammation, or necrosis. There have been numerous reports describing the cytomorphologic features of several organisms seen in FNA and tissue specimens. The pathologist also needs to be aware of the potential for a false-negative diagnosis of neoplasms in those lesions having a prominent inflammatory component as well as the potential for false-positive diagnosis of malignancy when inflammatory atypia and a repair reaction is present. The interaction of anatomic pathologists and clinical microbiologists is essential for appropriate workup of specimens with an infectious disease etiology. Thus, pathologists need to be well versed in both the anatomic and clinical pathology features of infectious diseases. Finally, those involved with FNA biopsy and handling of surgical pathology specimens should use universal precautions, since all patients are potentially infectious with the HIV virus and other communicable agents.