pathology histopathology exam md residency

1. Fungal infections
Dr. Manisha Tambekar

2. Fungal infection
• Fungal infections are called mycoses.
• Fungi are eukaryotes that grow by budding
( yeasts) or by filamentous extentions called
(molds)
• Candida albicans produce buds that fail to
detach become elongated, producing a chain
of elongated yeast cells called pseudohyphae.

3. Structure
• Main body: made up of fine, branching
colorless threads called hyphae.
• An individual fungal filament is called hypha.
• Several of these hyphae, all interwining to
make up a tangled web called the mycelium.

4. Morphological Classification
• Moulds : hyphae in form. Eg: ringworm or
dermatophytes.
• Yeasts : Single cell that bud to reproduce. Eg:
cryptococcus neoformans.
• Yeast like: Form Pseudohyphae. Eg: candida
albicans.
• Dimorphic fungi: have both a yeast form ( at
human body temp) and a mold form ( at
room temp ) eg: Blastomyces dermatitides.

5. Classification
• According to pathogenicity
1.Superficial mycoses
2.Mucocutaneous mycoses
3.Subcutaneous mycoses
4.Deep Mycoses / systemic.

6. Candidiasis
• Resides in the skin, mouth, GIT & vagina.
• Healthy people: live as benign commensals &
produce no disease.
• Candida albicans : frequent cause of human
fungal infections.
• Candida albicans grows on warm, moist surfaces
causing oral thrush, vaginitis & diaper rash.
• Diabetic & burn patients are prone to superficial
candida.

7. Candidiasis
• Directly introduced into the blood by IV lines,
catheters, peritoneal dialysis, cardiac surgery
or IV drug abuse.
• Disseminated candidiasis: Asso. with
neutropenia.
• Secondary to leukemia or anticancer therapy,
immunosupression after transplantation 7
neutrophil disorders.
• Causes shock & DIC.

8. Candidiasis
• Tissue sections: appears as yeastlike &
pseudohyphae.
• Pseudohyphae: imp diagnostic clue for C.
albicans & represent budding yeast cells
joined end to end at constrictions.
• Special stains : GMS ( gomori methenamine –
silver) & PAS ( periodic acid schiff)

9. Candidiasis
• Oral thrush: superficial infection on mucosal
surfaces of the oral cavity.
• Gray-white, dirty looking pseudomembranes
composed of matted organisms & inflammatory
debris.
• Mucosal hyperemia &inflammation.
• Commonly seen in newborns, debilitated pts.,
children receiving oral steroids for asthma &
following a course of antibiotics that destroy
competing normal bacterial flora & in HIV.

10. Oral thrush

11. Candida esophagitis
• Commonly seen in AIDS
patient & with
hematolymphoid
malignancy.
• Dysphagia, retrosternal
paining.
• Endoscopy: white
plaques &
pseudomembranes
resembling oral thrush.

12. Candidiasis

13. Candida esophagitis

14. Budding yeast

15. Candida vaginitis
• Common infection in diabetics or pregnant or
on oral contraceptive pills.
• Intense itching & a thick curd like discharge.
Chronic mucocutaneous candidiasis
• Chronic refractory disease afflicting mucous
membranes, skin, hair & nails.
• Asso. with underlying T-cell defect.

16. Cutaneous candidiasis
• Present in different forms
• Infection of nail proper :Onychomycosis
• Nail folds : Paronychia
• Hair follicles: folliculitis.
• Moist, intertriginous skin such as armpits or
webs of the fingers and toes : intertigo &
penile skin : Balanitis
• Diaper rash : seen in the perineum of infants ,
in the region of contact of wet diapers.

17. Invasive candidiasis
• Caused by blood- borne dissemination of
organisms to various tissues or organs.
• Common patterns :
1.Renal abscesses
2.Myocardial abscesses & endocarditis
( occurring in the setting of prosthetic valves
or in IV drug users).
3.Meningitis with parenchymal micro abscesses
4.Endopthalmitis

18. Invasive candidiasis
5. Hepatic abscesses
6. Candida pneumonia: B/L nodular infiltrates.
occurs in patient with acute leukemia's who are
neutropenic post-chemotherapy.

20. Cryptococcosis
• Cryptococcus neofarmans: encapsulated yeast
,causing meningoencephalitis in normal
individuals
• As opportunistic infection in pts. With AIDS,
leukemia, lymphoma, SLE, Hodgkin’s
lymphoma or sarcoidosis & in transplant
recipients.
• Present in soil & in bird (pigeon) droppings &
infects pts when it is inhaled.

21. Cryptococcosis
• It has yeast but not pseudohyphal or hyphal
forms.
• It has thick gelatinous capsule, valuable for
diagnosis.
• Capsular polysaccharites stains intense red
with PAS and mucicarmine in tissues and
detected with antibody-coated beads in an
agglutination assay.

22. Cryptococcosis
• India ink preparations create a negative
image, visualizing thick capsule as a clear halo
within a dark background, do not stain the
yeast.
• Lung – primary site of localization, mild
asymptomatic, forms solitary pulmonary
granuloma.
• CNS: Involving meninges, cortical gray matter
and basal nuclei.

23. Cryptococcosis
• In imunosuppressed gelatinous masses of fungi grow
in the meninges or expand perivascular Virchow-
Robin spaces within gray matter producing so-called
soap-bubble lesions.
• In non imunosuppressed patients or in those with
protracted disease fungi induce a chronic
granulomatous reaction composed of macrophages,
lymphocytes and FB type giant cells.
• In severely imunosuppressed: may disseminate
widely to skin, liver, spleen, adrenals and bones.

24. In lymphnode: mucicarmine stsain

25. India Ink

26. Aspergillosis
• It is a ubicutous mold that causes allergies
(brewer’s lung) and sinusitis, pneumonia and
fungemia in imunosuppressed patient.
• Factors that predispose to aspergillus
infectuon are neutropenia and
corticosteroids.
• They are transmitted by air-borne conidia, and
the lung is the major portal of entry.

27. Colonizing aspergillosis (aspergilloma)
• Implies growth of fungus in pulmonary cavities with
minimal or no invasion of the tissues.
• Cavities result from pre-existing tuberfungal
hypculosis, bronchitctasis, old infarcts, or abscesses.
• Prolifarating masses of fungal hyphae called fungal
balls form brownish masses lined free within cavities.
Chronic inflammation and fibrosis may also seen.

28. Invasive aspergillosis
• An opportunistic infection confined to
immunosuppressed and devilitated hosts.
• Priamry are seen in lung.
• Hematogenous dissemination involves heart
valves, brain and kidneys.
• Pulmonary lesions: necrotizing pneumonia
with sharply delineated, rounded, gray foci
with hemorrhagic borders referred to as
target lesions.

29. Invasive aspergillosis
• Aspergillus forms fruiting bodies and septate
filaments branching at acute angles(40
degree).
• They invade blood vessels.

30. Aspergillosis...

31. Aspergillosis : Grocott's methenamine silver GMS stained .

32. Zygomycosis (mucormycosis)
• Opportunistic infection caused by bread mold
fungi. These fungi are widely distributed in
nature and cause no harm to healthy
individuals.
• They infect immunosuppressed patients.
• Predisposing factors: neutropenia CS use, DM
and breakdown of cutaneous barrier (example
burns, surgical wounds, trauma).

33. Zygomycosis (mucormycosis)
• Transmitted by air-borne asexual spores.
• Inhaled spores produce infection in sinuses and
lungs.
• They form nonseptate, irregularly wide fungal
hyphae with frequent right-angle branching.
• Primary sites of invasion are nasal sinuses, lungs and
GIT.
• In diabetics fungus spread from sinus to the orbit
and brain giving rise to rhinocerebral mucormycosis.

34. Zygomycosis (mucormycosis)
• They cause local tissue necrosis, invade
arterial walls and penetrate periorbital tissues
and cranial vault.
• Meningoencephalitis follows, cerebral
infections and induced thrombosis.
• Lung: hemorrhagic pneumonia with vascular
thrombi and distil infarctions.

35. mucormycosis

36. mucormycosis

37. Histomorphological characteristic of
aspergillosis & mucormycosis
Characteristic Aspergillus Mucormycosis
Width Narrow ( 3-6 µm) Wide (5-20 µm)
Caliber
Uniform Varying
Branching Regular ( acute angle) Random ( Right angle)
Branching orientation Parallel/radial Random
Septum Common finding uncommon