Special Stains Use in Fungal Infections - Dako

No staining was seen in Cryptococcus or Candida, and very rare acid
fast staining was seen in coccidiodomyces endospores (12). However,
these staining properties are inconsistent and should not be used for
primary diagnosis. The cell walls of fungi are in general, not acid fast.
Autoflourescent Fungi
Some fungi or fungal components in the H&E stained tissue sections
are autofluorescent when examined under ultraviolet light source
(13). Candida species, Coccidioides immitis and Aspergillus species
can exhibit bright green to yellow-green autofluorescence (14). When
sections of these fungi are stained with the PAS, bright yellow fungal
autofluorescence against a deep red-orange background is seen (15).
Autofluorescence may help delineate sparse or poorly stained fungi in
H&E stained sections, however this property is inconsistent and should
not be used for definitive diagnosis. Most fungi in frozen or paraffin
embedded tissue sections also stain nonspecifically with Calcofluor
white, a cotton whitener that fluoresces under ultraviolet light (16). This
rapid and a simple fluorescence procedure can be routinely used in the
intraoperative examination of fresh-frozen tissues for fungi.
Immunoperoxidase stains can be used to identify certain fungi in
smears and in formalin fixed, paraffin embedded tissue section. This
technique, however, has only limited diagnostic use (17).
References
1. Chandler FW, Watts JC. Pathologic Diagnosis of Fungal
Infections. Chicago: ASCP Press; 1987.
2. Haque AK, McGinnis MR. Chapter 10. Dail and
Hammar’s Pulmonary Pathology. New York: Springer;
2008
3. Liber AF, Choi HS. Splendore-Hoeppli phenomenon
about silk sutures in tissue. Arch Pathol Lab Med. 1973;
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4. Schwartz J. The diagnosis of deep mycoses by
morphologic methods. Hum Pathol. 1982; 13:519-33.
5. Vacca LL. Laboratory Manual of Histochemistry. New
York: Raven; 1985.
6. Chandler FW, Kaplan W, Ajello L. Color Atlas and Text of
the Histopathology of Mycotic Disease. Chicago: Year
Book Medical; 1980.
7. Youngberg GA, Wallen EDB, Giorgadze TA. Narrow-
Spectrum histochemical staining of fungi. Arch Pathol
Lab Med 2003; 127:1529-1530.
194 | Connection 2010
8. Hussain Z, Martin A, Youngberg GA. Blastmyces
dermatitides with large yeast forms. Arch Pathol Lab
Med 2001; 125:663-664.
9. Kwon-Chung KJ, Hill WB, Bennett E. New, special stain
for histopathological diagnosis of cryptococcosis. J Clin
Microbiol. 1981; 13:383-87.
10. Lazcano O, Speights VO Jr, Stickler JG, Bilbao JE,
Becker J, Diaz J. Combined histochemical stains in the
differential diagnosis of Cryptococcus neoformans. Mod
Pathol 1993; 6:80-84.
11. Wood C, Russel-Bell B. Characterization of pigmented
fungi by melanin staining. Am J Dermatopathol. 1983;
5:77-81.
12. Wages DS, Wear DJ. Acid-fastness of fungi in
blastomycosis and histoplasmosis. Arch Pathol Lab
Med. 1982; 106:440-41.
13. Mann JL. Autofluorescence of fungi: an aid to detection
in tissue sections. Am J Clin Pathol. 1983; 79:587-90.
14. Graham AR. Fungal autofluorescence with ultraviolet
illumination. Am J Clin Pathol. 1983; 79:231-34.
Direct Immunofluoresence (IF)
Direct immunofluoresence (IF) can improve the diagnostic capability
of conventional histopathology in the diagnosis of fungal diseases
(18). The IF procedure, which can be performed on smears and on
formalin fixed paraffin embedded tissue sections is helpful in confirming
a presumptive histologic diagnosis, especially when fresh tissues
are not available for culture or when atypical fungus forms are seen.
The Division of Mycotic Diseases, Center for Disease Control, Atlanta
(United States) and others have a broad battery of sensitive and specific
reagents available for identifying the more common pathogenic fungi.
The immunofluoresence procedure has several advantages. Final
identification of an unknown fungus is possible within hours after
H&E and GMS stained sections are initially examined. The need
for time consuming and costly cultures is often obviated by IF, and
the hazards of handling potentially infectious materials are reduced
when microorganisms are inactivated by formalin prior to IF staining.
Prolonged storage of formalin fixed tissues, either wet tissue or paraffin
embedded, does not appear to affect the antigenecity of fungi. This
antigenic stability makes possible retrospective studies of paraffin
embedded tissue and the shipment of specimens to distant reference
laboratories for confirmatory identification. Most service laboratories,
however, do not routinely use IF, since the special stains have been very
reliable for diagnosis in the day to day pathology practice.
15. Jackson JA, Kaplan W, Kaufman L. Development of
fluorescent-antibody reagents for demonstration of
Pseudallescheria boydii in tissue. J Clin Microbiol. 1983;
18:668-73.
16. Monheit JE, Cowan DF, Moore DG. Rapid detection of
fungi in tissue using calcofluor white and fluorescence
microscopy. Arch Pathol Lab Med. 1984; 108:616-18.
17. Kobayashi M, Kotani S, Fujishita M, et al.
Immunohistochemical identification of Trichosporon
beigelii in histologic sections by Immunoperoxidase
method. Am J Clin Pathol. 1988; 89:100-05.
18. Reiss E, de-Repentgny L, Kuykendall J, et al.
Monoclonal antibodies against Candida tropicalis
mannans antigen detection by enzyme immunoassay
and immunofluorescence. J Clin Microbiol. 1986;
24:796-802.