Updated: 10/22/2020

Systemic Mycoses

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Snapshot
  • A 35-year-old woman presents to her primary care physician for a 2-week history of dry cough and worsening shortness of breath. She reports that she also has joint pains in her knees and ankles, as well as a rash on her legs. She recently traveled to southern California on a business trip, where she hiked with the team in the desert. A small earthquake occurred on the 2nd day of her business trip. On physical exam, she has multiple nodules on her anterior shins. A chest radiograph shows a consolidation in the right lower lung field. (Coccidioidomycosis)
Introduction
  • Introduction
    • dimorphic yeasts
      • mold form in the soil, outside the body
        • grows on Sabouraud agar
      • yeast form in tissues, inside the body
        • grows on blood agar
      • Coccidioides immitis is an exception
        • spherule form, not yeast, in tissue
    • demographics
      • depends on geographic location
    • transmission
      • inhalation of spores
      • cannot be transmitted between people
    • pathogenesis
      • inhalation causes a pulmonary infection
      • fungi can then disseminate to other organs, particularly the skin
      • causes granulomas
        • composed of epithelioid cells and multinucleated giant cells
        • Th1 mediated
    • clinical syndromes
      • pneumonia
      • chronic inflammatory lung disease
      • systemic dissemination
Overview of Systemic Mycoses
Clinical Syndrome Histoplasmosis
Coccidioidomycosis
Blastomycosis Paracoccidioidomycosis
Organism
  • Histoplasma capsulatum
  • Coccidioides immitis
  • Coccidioides posadasii
  • Blastomyces dermatitidis
  • Paracoccidioides brasiliensis
  • Paracoccidioides lutzii
Demographics
  • Mississippi
  • Ohio River Valley
  • Southwestern US
  • California
  • Eastern US
  • Central US
  • Latin America
Skin manifestations
  • Ulcers on oral mucosa
  • Erythema nodosum
  • Erythema multiforme
  • Verrucous skin lesions
  • Verrucous skin lesions
Histology
  • Macrophages filled with fungus cells
  • Spherules (larger than red blood cells (RBCs)) filled with endospores
  • Broad-based budding yeast (same size as RBCs)
  • Budding yeast larger than RBCs
 
  • Differential
    • tuberculosis
      • also affects the pulmonary system
      • causes granulomas, cavitations, and calcifications
      • unlike these systemic mycoses, tuberculosis can be transmitted person to person
  • Treatment
    • amphotericin B
      • systemic infections
    • itraconazole or fluconazole
      • localized infections
Histoplasmosis
  • Histoplasma capsulatum
    • demographics
      • Mississippi
      • Ohio River Valley (Ohio and Tennessee)
    • risk factors
      • bird or bat excretions
      • chicken farms
      • exploring caves or spelunking
      • HIV infection
  • Presentation
    • pneumonia
      • usually self-limiting
    • chronic cavitary lung disease
    • hilar lymphadenopathy
    • gastrointestinal symptoms
    • splenomegaly
    • oral mucosal ulcers on tongue or palate
  • Imaging
    • chest radiograph
      • normal or with patchy infiltrates with hilar/mediastinal lymphadenopathy
  • Studies
    • detection of antigen in serum or urine
    • tissue biopsy
      • methenamine silver or periodic acid-Schiff stains show oval yeasts within macrophages   
Coccidioidomycosis
  • Coccidioides immitis or Coccidioides posadasii
    • demographics
      • southwestern US
        • Arizona, New Mexico, and southern California
      • Central and South America
    • risk factors
      • earthquakes release spherules from soil
  • Presentation
    • pneumonia
    • dissemination to skin in 50% of patients
      • erythema nodosum
        • “desert bumps”
      • erythema multiforme
    • arthralgias
      • “desert rheumatism”
    • meningitis
  • Imaging
    • chest radiograph
      • consolidations, hilar/mediastinal lymphadenopathy, or pleural effusions
    • chest computed tomography (CT)
      • multifocal ground glass opacities
  • Studies
    • detection of immunoglobulin M (IgM) in serum
    • detection of antigen in serum
    • tissue biopsy
      • spherules (larger than RBCs) filled with endospores
Blastomycosis
  • Blastomyces dermatitidis
    • demographics
      • eastern US
      • central US
    • risk factors
      • HIV infection
  • Presentation
    • majority are asymptomatic
    • pneumonia
    • severe chronic inflammatory lung disease
    • dissemination to skin, often on the face
      • verrucous skin lesions
      • granulomatous nodules
      • ulcers
  • Imaging
    • chest CT
      • infiltrates without hilar lymphadenopathy
      • cavitary lesions in chronic disease
  • Studies
    • tissue biopsy
      • fungal stain shows broad-based budding yeast
      • same size as red blood cells (RBCs)
Paracoccidioidomycosis
  • Paracoccidioides brasiliensis or Paracoccidioides lutzii
    • also known as “South American blastomycosis”
    • demographics
      • Latin America
      • male > female
    • risk factors
      • contact with soil
  • Presentation
    • severe chronic inflammatory lung disease
    • pneumonia
    • lymphadenopathy
    • dissemination to skin, often on the face but can also affect mucous membranes
      • verrucous skin lesions
      • granulomatous nodules
  • Imaging
    • chest radiograph
      • bilateral iniltrates without cavitation
  • Studies
    • tissue biopsy
      • budding yeast
      • "captain’s wheel” formation
      • granulomas
 

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(M1.MC.14.14) A 59-year-old man with no significant past medical history presents to the emergency room with the ulcerative skin lesion shown in Figure A. He had a bad pneumonia several weeks ago. His vital signs are stable, and the remainder of his physical examination is benign. The lesion is swabbed and cultured revealing the organism shown in Figure B. Which of the following is most likely true regarding this disease? Tested Concept

QID: 104899
FIGURES:
1

The patient received the illness from bat droppings and may be treated with PO itraconazole

13%

(6/46)

2

The patient received the illness in the Southwest and may be treated with PO fluconazole or itraconazole

33%

(15/46)

3

The patient received the illness in the Eastern USA and may be treated with PO itraconazole

39%

(18/46)

4

The patient received the illness in Latin America and the organism may form a captain's wheel formation

2%

(1/46)

5

The patient received the illness from plant material and may be treated with potassium iodide

11%

(5/46)

M 2 D

Select Answer to see Preferred Response

(M1.MC.13.12) A 43-year-old man presents to the emergency department with cough and fever. On a sputum sample he is found to have spherules containing endospores, as shown in Figure A. How is he most likely to have contracted his disease? Tested Concept

QID: 101471
FIGURES:
1

Hunting in the woods of Connecticut

3%

(17/502)

2

Swimming in a freshwater pond in Louisiana

6%

(28/502)

3

Hiking in the deserts of Arizona

50%

(253/502)

4

Walking in caves in the Mississippi River Valley

19%

(96/502)

5

Cleaning out pigeon coops in Ohio

18%

(91/502)

M 1 E

Select Answer to see Preferred Response

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