Candidiasis pathology

Candida albicans is the most frequent Candida species that infects humans. Is organism it is a yeast-like fungus with budding and filamentous forms (pseudohyphal and hyphal). It can cause a wide range of clinical manifestations ranging from mild acute superficial to fatal infections disseminated disease. Disseminated candidiasis is seen almost exclusively in acquired or inherited immunodeficiencies. Superficial candidiasis is the most common form.

Histology of yeast infection

In candidiasis, sections show predominantly spongy changes in the epidermis with irregular acanthosiswarm spongiosis and inflammatory changes (figure 1). In the superficial epidermis, the characteristic feature is the presence of neutrophils at stratum corneum and upper layers of the epidermis. Neutrophils can form small collections (spongiform postulation) that resembles impetigo or psoriasis (Figure 2).

Special spots for candidiasis.

Special stains to demonstrate the yeast forms are essential in yeast infection.

• Silver staining with Gomori methanamine (GMS). The stain highlights the pseudohyphal or hyphal forms (figure 3, arrows) that penetrate the keratinized. epithelium. In addition, there are yeast forms in the superficial stratum corneum (Figure 3, red arrowhead).
• PAS staining can also be used to highlight organisms.

Differential diagnosis of yeast infection pathology

Pustular psoriasis, subcorneal generalized subcorneal acute pustolosis pustulosis - Spongiform postulation can also be seen under these conditions. Special spots should be carefully examined in cases of psoriasis to exclude a fungus etiology.

Impetigo: Spongiform postulation is a hallmark of impetigo. Gram stain can highlight bacterial impetigo colonies that GMS and PAS stains will not reveal fungal forms.

Dermatophytosis: Spongiform postulation is a hallmark of tinea cruris and corporis. The special spots show septate hyphae without budding candida yeasts. The distinction can sometimes be difficult. Candida often penetrates the keratinized epithelium (Figure 3) rather than dermatophytosis, which generally involves only the stratum corneum.