Thoracic Pathology: A Volume in the High Yield Pathology Series 1st Edition

Candidiasis

Definition

• A fungal infection caused by Candida spp.

Pathogenesis

• Candida are ubiquitous yeastlike fungi that normally inhabit the gastrointestinal and upper respiratory tracts without causing symptoms

• Opportunistic infections occur only when host immune system is compromised

Clinical features

Epidemiology

• Candida is the most common fungal pathogen in immunocompromised patients

• However, Candida pneumonia is rare and usually secondary to hematogenous dissemination or aspiration from oral cavity or upper respiratory tract

• Candida albicans is the most common pathogen

Presentation

• Patients usually present with fever, coughing, purulent sputum, and shortness of breath

Prognosis and treatment

• Poor prognosis with high mortality rate, even after intensive antifungal treatment

Pathology

Histology

• If infection is secondary to aspiration there is acute bronchopneumonia or granulomatous inflammation with associated Candida fungal organisms

• Miliary nodules of necrosis and inflammation around vessels are indicative of hematogenous spreading

• Organisms are budding yeasts with pseudohyphae

• Rarely, giant blastoconidia may be present

Immunopathology/special stains

• GMS and PAS stains help identify the presence of fungal organisms

Main differential diagnoses (see Table 6 in the Appendix)

• Histoplasmosis

• Aspergillosis

• Zygomycosis

• Giant blastoconidia should be distinguished from Cryptococcus, Blastomyces, or Paracoccidioides

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Fig 1 Candidiasis. Candida pneumonia with granulomatous inflammation with multinucleated giant cell formation.

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Fig 2 Candidiasis. Candida organisms with pseudohyphae and budding yeasts: H&E stain (A) and GMS stain (B). Note the presence of blastoconidia.



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