In pseudomembraneous candidiasis, the membranous slough can be wiped away to reveal an erythematous surface underneath. This is helpful in distinguishing pseudomembraneous candidiasis from other white lesions in the mouth that cannot be wiped away, such as lichen planus, oral hairy leukoplakia. Erythematous candidiasis can mimic geographic tongue. Erythematous candidiasis usually has a diffuse border that helps distinguish it from erythroplakia, which normally has a sharply defined border. Special investigations to detect the presence of candida species include oral swabs, oral rinse or oral smears. Smears are collected by gentle scraping of the lesion with a spatula or tongue blade and the resulting debris directly applied to a glass slide. Oral swabs are taken if culture is required. Some recommend that swabs be taken from 3 different oral sites. Oral rinse involves rinsing the mouth with phosphate-buffered saline for 1 minute and then spitting the solution into a vessel that examined in a pathology laboratory. Oral rinse technique can distinguish between commensal candidal carriage and candidiasis. If candidal leukoplakia is suspected, a biopsy may be indicated. Smears and biopsies are usually stained with periodic acid-Schiff, which stains carbohydrates in fungal cell walls in magenta. Gram staining is also used as Candida stains are strongly Gram positive. Sometimes an underlying medical condition is sought, and this may include blood tests for full blood count and hematinics. If a biopsy is taken, the histopathologic appearance can be variable depending upon the clinical type of candidiasis. Pseudomembranous candidiasis shows hyperplastic epithelium with a superficial parakeratotic desquamating (i.e., separating) layer. Hyphae penetrate to the depth of the stratum spinosum, and appear as weakly basophilic structures. Polymorphonuclear cells also infiltrate the epithelium, and chronic inflammatory cells infiltrate the lamina propria. Atrophic candidiasis appears as thin, atrophic epithelium, which is non-keratinized. Hyphae are sparse, and inflammatory cell infiltration of the epithelium and the lamina propria. In essence, atrophic candidiasis appears like pseudomembranous candidiasis without the superficial desquamating layer. Hyperplastic candidiasis is variable. Usually there is hyperplastic and acanthotic epithelium with parakeratosis. There is an inflammatory cell infiltrate and hyphae are visible. Unlike other forms of candidiasis, hyperplastic candidiasis may show dysplasia. Treatment Oral candidiasis can be treated with topical anti-fungal drugs, such as nystatin, miconazole, Gentian violet or amphotericin B. Surgical excision of the lesions may be required in cases that do not respond to anti-fungal medications. Underlying immunosuppression may be medically manageable once it is