Chapter 6: Fungal diseases Flashcards
Candidiasis
-‐ Most common oral fungal infection in humans (carried by 30-‐50% of people)
-‐ Dimorphic organism: Yeast-‐ innocuous; hyphae-‐ invasive
-‐ Pseudomembranous, erythematous, chronic hyperplasitc and mucocutaneous forms
-‐ Pseudomembranous candidiasis: thrush. Due to antibiotics or impairment of immune system
-‐ Acute atrophic candidiasis: most common form. Due to antibiotics.
-‐ Median rhomboid glossitis (central papillary atrophy): posterior dorsal tongue
-‐ Chronic multifocal candidiasis: median rhomboid glossitis + palate (kissing lesion) or angles of mouth (angular cheilitis or perleche)
-‐ Angular cheilitis: 20% C.albicans, 20% S.aureus, 60% C.albicans+S.aureus
-‐ Cheilocandidasis: perioral extension of candida secondary to actions that keep the skin moist
-‐ Denture stomatitis: chronic atrophic candidiasis
-‐ Chronic hyperplastic candidiasis: white plaque that does not wipe off
-‐ Mucocutaneous candidiasis: mouth, nails and skin. Oral-‐chronic hyperplastic. IgA def. Mutation in AIRE gene (auto-‐Ab against endocrine glands). Pts may develop APECED and iron-‐def anemia
-‐ APECED: autoimmune polyendocrinepathy-‐candidiasis-‐ectodermal dystrophy syndrome.
Includes hypothyroidism, hypoparathyroidism (Chvostek’s sign), hypoadrenocorticism (Addison’s) and diabetes. Also increased risk of oral and esophageal carcinoma.
-‐ Stain: PAS (carbohydrates), potassium hydroxide (KOH) or Grocott-‐gomori methenamine silver
-‐ Candida treatment: nystatin, clotrimazole (topical), ketoconazole, fluconazole (systemic)
Histoplasmosis
-‐ Caused by Histoplasma capsulatum. Endemic in river valleys (Ohio/Mississippi)
-‐ Droppings from chickens, pigeons, starlings, blackbirds, and bats
-‐ Most common systemic fungal infection in US
-‐ Acute (most common), chronic (similar TB; upper lobe changes, calcifications) and disseminated (oral lesions-‐ ulcer ~ SCC)
-‐ Stain: PAS or Grocott-‐Gomori methenamine silver
Blastomycosis (Chicago disease)
-‐ Blastomyces dermatitis. 10x more in males (outdoor activity)
-‐ Habitat ~ histoplasmosis: humid, moist soil (river valleys; Ohio, Mississippi) but extends north
-‐ Acute (similar pneumonia) and chronic (mimics TB)
-‐ Facial skin nodules that enlarge and become verrucous or ulcerated. Oral: ~ SCC
-‐ Stains: PAS and Grocott-‐Gomori methenamine silver
Paracoccidioidomycosis
-‐ Oral: mulberry-‐like ulcerations
– Distinct predilection for male M:F 15:1 (Attributed to protective effect of female hormones (β-estradiol inhibits the transformation of the hyphal form of the organism to the pathogenic yeast form))
– nine-banded armadillo as resevoir
-‐ Stain: PAS, grocott. Mickey-‐mouse ears or mariner’s wheel
Coccidioidomycosis
-‐ Coccidioides immitis. Found in desert soil (southwestern US and Mexico).
-‐ Acute, chronic progressive pulmonary (mimics TB) and disseminated
-‐ EM-‐like skin eruption or erythema nodosum: painful erythematous nodules subcutaneously
-‐ Valley fever: coccidioidomycosis + erythema nodosum
-‐ Disseminated: skin lesions (papules, abscess, verrucous plaques or granulomatous nodules) on central face, esp. nasolabial fold. Oral lesions rare
-‐ Histo: large 20-‐60 um round spherules with numerous endospores
-‐ Stain: PAS, grocott
Cryptococcosis
-‐ Cryptococcus neoformans. Pigeon excrement (worldwide distribution)
-‐ Mucous capsule is mucopolysaccharide (mucicarmine) positive
-‐ Acute or disseminated (most commonly to meninges and skin)
-‐ Cryptococcal meningitis: headache, fever, vomiting
-‐ Skin: erythematous papules/pustules that may ulcerate and discharge material rich in organisms
-‐ Oral: rare. Similar to SCC
Zygomycosis (mucormycosis, phycomycosis)
-‐ Caused by zygomycetes (mucor, absidia).
-‐ Most relevant form: rhinocerebral form
-‐ Mucor seen in uncontrolled and ketoacidotic diabetics (increased iron levels, which enhances fungus growth). Also pts with thalassemia using deferoxamine (increases iron levels too)
-‐ Oral: black and necrotic palate ulceration (extension from sinus involvement)
-‐ Non-‐septate branching hyphae 90 degrees, extensive tissue destruction (predilection for vessels, causing infarction and necrosis)
-‐ 60% mortality rate
Aspergillosis
-‐ 90% due to A.fumigatus. Also A. flavus
-‐ Non-‐invasive (allergic fungal sinusitis or fungus ball-‐aspergilloma) or invasive
-‐ Invasive in AIDS, CT, organ transplant, uncontrolled diabetes
-‐ Commonly acquired as nosocomial (in hospital), especially if there’s construction nearby
-‐ Aspergilloma can undergo dystrophic calcificaiton and give rise to antrolith
-‐ May develop after tooth extraction or endo, esp in post MX
-‐ Oral aspergillosis: gingival ulcerations and swelling with surrounding gray/violaceous hue
-‐ Disseminated aspergillosis: seen in patients with leukemia or under corticoids
-‐ Invasive aspergillosis: fruiting bodies, septate branching hyphae at 40” acute angle (< mucor)
-‐ Aspergilloma: tangled mass of hyphae
-‐ AFS: laminated apperance, inspissated mucin (w/ entrapped eosinophils), few hyphae
-‐ Charcot-‐Leyden crystals: eosinophilic hexagonal pyramidal crystals derived from eos in AFS
-‐ AFS stains: GMS or Fontana-‐Masson
-‐ Tx: aspergilloma-‐debridement; AFS-‐debridement+corticoids; invasive-‐voriconazole
Rhinosporidiosis
-‐ Caused by Rhinosporidium seeberi
-‐ 90% in India and Sri Lanka
-‐ Histo: 100-‐300 um cysts or sporangia w/ numerous endospores (immature-‐small; mature-‐large)
Yeast sizes (large -> small)
Histoplasmosis < Cryptococcosis < Blastomycosis < PCM < Coccidioidomycosis < Rhinosp Hyphae sizes: Aspergillosis < Mucormycosis
Toxoplasmosis
-‐ Toxoplasma gondii: cat is the host, oocysts found in cat’s feces
-‐ Mononucleosis-‐like symptoms in immunocompetent host
-‐ Congenital toxoplasmosis: blindness, mental retardation, delayed psychomotor development
-‐ Histo: triad of follicular hyperplasia, clusters of epithelioid histiocytes and plasmacytoid B cells
-‐ Dx: serum Ab titers
Cysticercosis
-‐ Infection of human tissues by Taenia solium
-‐ Acquired through ingestion of undercooked pork meat
-‐ Neurocysticercosis: most common symptom is epilepsy
-‐ Histo: cystic cavity containing the larval form of Taenia solium. The scolex seen at the cephalic region and caudal to it, a duct-‐like invagination is noted. This invagination is lined by an eosinophilic membrane. Higher magnification of the caudal region may show few ovoid basophilic calcified corpuscles
