Infectious Disease Online
Pathology of Candidosis (Candidiasis)
Candida albicans is the most common fungal pathogens of
These are normal inhabitants of oral cavity, GI tract, and vagina.
Fungi are yeast-like cell with pseudohyphae and hyphae.
i) Prolonged antibiotic or steroid therapy.
ii) Diabetes mellitus, advanced malignancy, pregnancy, oral contraceptives etc.
iii) Burns, surgery, urinary tract catheters and GI tract ulcers etc.
iv) Frequent exposure of body or hands or feet to water.
Most common site is superficial mucosal surface of oral cavity (thrush). Other sites include vagina, folds of skin and nail (middle finger is frequently involved).
Creamy-white, friable, patches composed of organisms and inflammatory debris, forms pseudomembrane.
It covers tongue, soft palate and buccal mucosa.
When detached, it leaves red, inflamed surface.
In severe cases, there is ulceration.
Pseudomembrane extends to perineum and develops in pregnancy or after oral contraceptives.
Acute Superficial candidosis is the usual form of lesion.
Chronic mucocutaneous candidosis is characterized by chronic and persistent infection of the mucous membrane by species of Candida.
Chronic lesions are seen in persons with immune defect.
Paronychia and onychomycosis may occur:
Location: Folds of skin in axilla, groin, inframammary area, intergluteal folds, interdigital spaces and umbilicus.
Gross: It shows pruritic eczematous area with vesicles or pustules in the margin.
"Candida granuloma"- this is a disfiguring cutaneous lesion and appears as warty, hyperkeratotic, papules or plaques.
(i) Neutrophils in the stratum corneum is the characteristic feature.
(ii) Diffuse inflammatory infiltrates and intraepithelial microabscesses.
(iii) Fungal elements are sparse and demonstrated with the PAS stain.
Silver methenamine stain (Grocott's method) : Stains fungal hyphae black against green backround.
It is more reliable than PAS for detecting degenerate fungal organisms.
Image: Psoriasiform epidermal hyperplasia in a case of chronic candidosis
i) Marked hyperkeratosis and pseudoepitheliomatous hyperplasia.
ii) Compact orthokeratosis and scale crust formation.
iii) Spores and hyphae are easily identified even without Periodic acid-Schiff (PAS) stains.
iv) Granulomatous dermatitis : ill-defined granulomas composed of lymphocytes, plasma cells, epithelioid cells and occasionally giant cells.
Image 1) Histopathology Image of Candida: Silver methenamine stain (Grocott's method) -Stains fungal spores and hyphae black against green backround
Image 2) Histopathology Image of Candida: Periodic acid-Schiff - Stain
Disseminated /Systemic Candidiasis:
Gastrointestinal tract: Mostly esophagus and stomach.
Lesions consist of punctate mucosal erosion or ulcer covered by pseudomembrane.
Organisms invade submucosa and submucosal blood vessels.
Urinary tract: Causes cystitis and ascending pyelonephritis, often papillary necrosis of kidney ; Necrotic material with fungi, forms "fungal balls" causing ureteric obstruction and hydronephrosis ; Bilateral miliary necrosis may be seen in hematogenous dissemination.
Central Nervous System: This is the most common fungal infection in CNS.
It causes multiple microabscesses with non-caseating granulomas and localized meningitis.
Lungs: i) By inhalation produce bronchopneumonia ; ii) By hematogenous spread cause bilateral hemorrhagic nodules.
Laboratory diagnosis: (Read :Histopathological Patterns in Cutaneous Infection )
Immunofluorescence and immunohistochemistry.
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