Incorporating Pathology in the Practice of Infectious Disease: Myths and Reality

Abstract

The role pathology plays in establishing or excluding infectious diseases has been established. However, as the practice of pathology has become subspecialized, there is not enough infectious disease specimen volume to have a pathologist dedicated full time to this crosscutting subspecialty. So, what are the myths and realities of a practicing infectious disease pathologist in the hospital setting? Infectious disease clinicians tend to consult pathologists when there are questions regarding terminology used in pathology reports; when there is the need to perform additional studies on formalin-fixed, paraffin-embedded tissues; and when there is an interest in seeing biopsies or resections obtained from patients and in obtaining photographs for presentations. Pathologists consult infectious disease pathologists when there is a need to review diverse inflammatory reactions; for identification of fungi, parasites, or unknown structures; to define the need to use special stains and other techniques in order to identify organisms in tissues that have been formalin fixed; and to help with terminology to be used in reports. This review explores in more detail why and how these consultations occur.

Using Immunohistochemistry to Assess the Accuracy of Histomorphologic Diagnosis of Aspergillosis and Mucormycosis

“…However, if a culture is not available or cannot be obtained, these newer methods may help obtain the most likely diagnosis possible. In addition, aware of the limitations of histomorphologic diagnosis, several authors have suggested that pathologists should describe the observed hyphae (septated vs pauciseptated, hyaline vs pigmented, plus morphologic features), followed by a comment indicating the various fungal genera that could have those morphologic features [26,27].…”

Microbial Identification Using DNA Target Amplification and Sequencing: Clinical Utility and Impact on Patient Management

“…Samples were also typically submitted for bacterial, mycobacterial, and fungal cultures. Pathological examination of tissue specimens was performed in the Pathology Laboratory at Tufts Medical Center, and samples were considered to have evidence of infection if there was infiltration with neutrophils, macrophages, or other inflammatory cells, or caseating granulomatous inflammation was seen [ 34 ].…”

Invasive Fungal Infections and Approaches to Their Diagnosis

“…Direct microscopic examination of clinical material is perhaps the most rapid, useful, and cost-effective means of diagnosing fungal infections (Chandler & Watts, 1987;Connor, Chandler, Schwartz, Manz, & Lack, 1997;Guarner, 2014;Guarner & Brandt, 2011;Koneman & Roberts, 2002;Shea, 2007). Detection of fungal elements microscopically may provide a diagnosis in less than an hour, whereas culture results are often not available for days or even weeks.…”

“…Although not widely available, specific immunofluorescent stains may be extremely helpful in confirming a presumptive histologic identification of some fungi such as Candida, Aspergillus, Fusarium, the dimorphic fungi, and others (Hayden et al, 2003;Hayden, Qian, Procop, Roberts, & Lloyd, 2002;Kaufman, Standard, Jalberl, & Kraft, 1997). Histologic examination of fixed tissue provides the opportunity to determine whether the fungus is in viable tissue, information that is useful in distinguishing between active infection and colonisation (Guarner, 2014;Guarner & Brandt, 2011). The microscopic morphologic features of several of the more common fungal pathogens are presented in Table 5.…”