Dr  Sampurna Roy  MD

Candida albicans is the most common fungal pathogens of mankind.

These are normal inhabitants of oral cavity, GI tract, & vagina. Fungi are yeast-like cell with pseudohyphae & hyphae.

Predisposing factors:

i) Prolonged antibiotic or steroid therapy.

ii) Diabetes mellitus, advanced malignancy, pregnancy, oral contraceptives etc

iii) Burns, surgery, urinary tract catheters & GI tract ulcers etc.

iv) Frequent exposure of body or hands or feet to water.

Site: 

 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)

Oral thrush:

Creamy-white, friable, patches composed of organisms & inflammatory debris, forms pseudomembrane. It covers tongue, soft palate & buccal mucosa. When detached, it leaves red, inflamed surface . In  severe cases, there is ulceration.

Vulvovaginal:

Pseudomembrane extends to perineum & develops in pregnancy or after oral contraceptives.

Skin:

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 & onychomycosis may occur.

Location: Folds of skin in axilla, groin, inframammary area, intergluteal folds, interdigital spaces & 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.

Microscope:    Image1 ;;  Image2

 Acute:  i)Neutrophils in the stratum corneum is the characteristic feature.e  ii) Diffuse inflammatory infiltrates & 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.

Chronic:  i) Marked hyperkeratosis & pseudoepitheliomatous hyperplasia. ii) Compact orthokeratosis &scale crust formation  iii )Spores and hyphae are easily identified even without PAS stains.  iv) Granulomatous dermatitis :  ill-defined granulomas composed of lymphocytes, plasma cells, epithelioid cells and occasionally giant cells.

Disseminated /Systemic Candidiasis:

Gastrointestinal tract:   Mostly esophagus & stomach. Lesions consist of punctate mucosal erosion or ulcer covered by pseudomembrane. Organisms invade submucosa & submucosal blood vessels.

Urinary tract:  Causes cystitis & ascending pyelonephritis, often papillary necrosis of kidney ; Necrotic material with fungi, forms “fungal balls” causing ureteric obstruction & hydronephrosis ; Bilateral miliary necrosis may be seen in hematogenous dissemination.

CNS:  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 & immunohistochemistry.

CLICK ON THE IMAGES

PAS stain

 Grocott's silver stain