PMC7343954_01
Bone marrow trephine biopsy with intracellular fungal yeasts (arrow) that are Periodic Acid Schiff positive with Alcian Blue Periodic Acid Schiff stain (original magnification x 400).
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F0001
Although fungal culture remains the gold standard, the diagnosis of a fungal infection can be reliably made on histological examination by identifying fungal yeasts (see Figure 1) or hyphae using histochemical stains such as Grocott and Periodic Acid Schiff (PAS).
Skin biopsy with numerous extracellular yeasts on haematoxylin and eosin (original magnification x 200), the inset shows the yeasts with blue capsules and pink cell walls on Alcian Blue Periodic Acid Schiff stain (original magnification x 400).
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Numerous extracellular yeasts were seen on haematoxylin and eosin stained section (Figure 2). The capsules and cell walls were highlighted on Alcian Blue Periodic Acid Schiff (ABPAS) special stain (Figure 2, inset) and the diagnosis of cryptococcosis was made. The typical staining on ABPAS special stain, as was noted in case 2 (see Figure 2), is supportive of the diagnosis.
PMC7343954_02
Bone marrow trephine biopsy showing histiocytes (arrows) (original magnification x 200) with acid fast bacilli in clumps on Ziehl Neelsen stain (inset) (original magnification x 400).
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F0003
Numerous, clumped intracellular acid-fast bacilli were noted on Ziehl Neelsen (ZN) stain (Figure 3). Although definitive mycobacterial species identification is not possible on histological examination, the finding of sheets of foamy histiocytes containing ZN and PAS-positive bacilli are suggestive of Mycobacterium avium complex as noted in case 3 (see Figure 3).
PMC7343954_03
A proliferation of capillaries is noted with basophilic clumps of bacteria, indicated by arrows, characteristic of bacillary angiomatosis (original magnification x 400).
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F0004
The bacilli in bacillary angiomatosis are noted as basophilic clumps in the tissue stroma where they proliferate (Figure 4).
PMC7343954_04
Numerous spirochaetes are identified on T. pallidum immunohistochemistry performed on the skin biopsy (original magnification x 400). A lichenoid lymphoplasmacytic infiltrate is noted on haematoxylin and eosin (inset) (original magnification x 200).
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A lichenoid lymphoplasmacytic infiltrate was noted on haematoxylin and eosin stained section (Figure 5, inset). Numerous spirochaetes were identified on Treponema pallidum immunohistochemistry, confirming the diagnosis of secondary syphilis (Figure 5). HIV infection are more likely to have atypical presentations and secondary syphilis at the time of diagnosis. Histopathological findings in secondary syphilis include epidermal hyperplasia and a moderate to dense lymphoplasmacytic infiltrate as were noted in case 5 (Figure 5, inset). T. pallidum immunohistochemical stain (Figure 5) is more sensitive than a silver stain.
PMC7343954_05
Perianal biopsy showing herpes simplex virus and Cytomegalovirus inclusions (inset) in the same biopsy (both original magnification x 400).
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F0006
Herpes simplex virus (HSV) and Cytomegalovirus (CMV) inclusions were both present in the perianal biopsy (Figure 6).
PMC7343954_06
Bone marrow trephine biopsy with numerous parvovirus inclusions (arrows) (original magnification x 400).
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Numerous parvovirus inclusions were noted on microscopic examination (Figure 7).
Fallopian tube with products of conception and an incidental finding of schistosomal ova (arrow) (original magnification x 100) and inset (original magnification x 400).
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F0008
Schistosomal ova were noted incidentally within the fallopian tube on microscopic examination (Figure 8).