Fungus in Histopathology

Advantages

• Speed, low cost

• Presumptive identification of the infecting fungus

• Demonstrating tissue reaction.

• Only way to diagnose- L. loboi or Rhinosporidium seeberi

Special Stains

TISSUE STAINING METHODS FUNGI

Skin and Subcutaneous Tissue

KOH , Giemsa, GMS Dermatophytes, Sporothrix,Zygomycetes

Nasal Smear Biopsy H and E, GMS Rhinosporidiosis

Muscle H and E, GMS Zygomycetes( very rare)

Bone Marrow Giemsa, GMS Histoplasma

Lung H & E, Giemsa, GMS and PAS

Aspergillus, C.Neoformans

Lymph Node H & E, Giemsa , GMS and PAS

Aspergillus, C.Neoformans

Mucin stains (Mayer’s mucicarmine and Alcian blue)-C. neoformans,Blastomyces dermatitidis and R. seeberi

Major forms

• Yeast cells

• Hyphae

• Pseudohyphae,

• Arthroconidia,

• Chlamydoconidia

• Spherules.

TRUE PATHOGENS

Cutaneous infective agents Subcutaneous infective agents

Epidermophyton speciesMicrosporum speciesTrichophyton species

Actinomadura maduraeCladosporium

Madurella griseaPhialophora

Sporothrix schenckii

Systemic infective agents

Blastomyces dermatitidisCoccidioides immitis

Histoplasma capsulatumParacoccidioides brasiliensis

OPPORTUNISTIC PATHOGENS

• Absidia corymbifera

• Aspergillus fumigatus

• Candida albicans

• Crytococcus neoformans

• Pneumocystis carinii

• Rhizomucor pusillus

• Rhizopus oryzae (R.arrhizus)

Case 1

• A 42 year old female

• Chronic asthma ( Inhaled corticosteroids)

• c/o- Productive cough (brown mucous, blood tinged)

• O/E- Mild Fever

• Chest X ray- Lobar Infiltrate (Clusters of grapes)

• CBC- Mildly elevated WBC count

- Markedly elevated eosinophil count

Diagnosis

• Aspergillosis Fumigatus (90%)

• Other Species- A.terreus, A.flavus

Case 2

• 52 year old male

• C/o – Cough and fever since 1 week a/w fatigue, headaches, joint pains at night .

• No history of pulmonary diseases or smoking

• Travel history to Phoenix 3 weeks ago

• O/E- Mild fever, wheezing in upper left chest

• X ray chest- Hilar adenopathy

• CBC- Normal TLC with eosinophilia

• KOH- Numerous spherules

Differential Diagnosis

• Blastomycosis

• Coccidomycosis ( C. immitis)

• Histoplasmosis

Case 3

• 68 year old male

• C/O- Dysphagia , retrosternal pain since 2 days, was on treatment for UTI

• O/E- Normal

• On Endoscopy- Thick , curdy white patches on esophageal wall

Diagnosis

Candida Albicans

Case 4

• 32 year old male

• K/C/O- Retroviral disease

• C/O- fever, headache x 3 days

• A/w- Confusion, forgetfullness

• O/E – Moderate grade fever, cranial nerves normal

• Minimal nuchal rigidity, hyperreflexic

• CSF- high TLC , lymphocyte predominant

• India Ink - Positive

Diagnosis

• Cryptococcus Neoformis

CASE 5

• 29 year old female

• C/o cough , worsening since weeks, low grade fever

• H/0 smoking half pack a day

• K/C/O- RVD

• O/E- Normal

• Anticubital veins- Needle Track

• Lungs- Decreased breath sounds, ronchi

• Chest Xray- Ground glass appearance

Diagnosis

• Pneumocystis Carinii

CASE 6

• 27 year old male

• Newly diagnosed HIV (CD 4 count- 7 cells/mm3)

• C/O- fever with chills, night sweats, myalgia, dry cough, loss of weight x 25 days

• O/E- 2 - 3 mm hyperpigmented papules and dermal basophilic spherules 2 - 4 microns

• Has been treated for Pneumonia

Diagnosis

• Histoplasma

Case 7

• 60 year old farmer

• c/o – Nasal obstruction, epistaxsis since one year .

• No comorbid conditions

• H/O Chronic smoking , occasional ethanolic

• O/E- Mass noticed in left nostril, reddish in color, strawberry like in appearence

• Diagnosis

Rhinosporidium seebri

CASE 8

• A 70-year-old male

• C/O- Bad breath and pus discharge from upper left region of jaw since one month.

• K/C/O - Diabetes mellitus

• Three months came to Emergency Department in an unconscious state- Diabetic ketoacidosis with renal failure

Diagnosis

Mucormycosis

Artefacts

• Tissue components such as Russell bodies, calcified bodies, elastic fibres and small blood vessels .

• Silver precipitates- collagen, fibrin, elastin , neutrophils, cytolytic debris.

• The KOH preparation – unstained fungal elements in skin, hair and nails

• Specimens- sputum and vaginal

• Calcofluor white

• Combination of the two.

• India ink preparation - C. neoformans in CSF

Newer Techniques

• Immunohistochemistry.

• In Situ Hybridization

• In Situ Polymerase Chain Reaction

• Fluorescent in situ hybridization (FISH)

REFERENCES

• Robbins and Cotran , South Asia Edition, Volume I &II

• Andersons 6 th Edition

• Case Files Microbiology , Lange

THANK YOU