Sinus and Rhinology Flashcards
Compare Yeast vs Mold
Yeast
- unicellular
- reproduce asexually by budding
- Pseudohyphae - when bud doesnt detach
Mold
- multicellular
- grow by branching - hyphae
What is this structure?
Aspergillus
- Septated hyphae with branching at 45⁰
What is this structure?
Mucormycosis
- Nonseptated hyphae with branching at 90⁰
What are the types of non-invasive fungal infections?
Non-invasive
- Saprophytic fungal infestation
- Sinus fungal ball (mycetoma)
- Allergic fungal sinusitis
What are the types of invasive fungal infections?
Invasive
- Acute fulminant invasive fungal sinusitis
- Chronic invasive fungal sinusitis
- Granulomatous invasive fungal sinusitis
Describe a sinus fungal ball (mycetoma)
- Sequestration of fungal elements within a sinus without invasion or granulomatous changes
- Inhaled spores grow while evading host immune system (no invasion)
- Aspergillus most common species
- Maxillary sinus most often involved (70-80% of cases)’
- Presents similar to rhinosinusitis with congestion, facial pain, headache, rhinorrhea
What are the CT scan findings of a fungal ball?
- Single sinus in 59-94% of cases (maxillary)
- Complete or subtotal opacification of sinus
- Radiodensities within the opacifications (due to increased heavy metal content)
- Bony sclerosis; destruction is rare (3.6-17% of cases)
- biopsy will show fungal elements
What is the treatment of a fungal ball (mycetoma)?
- Complete surgical removal of fungal ball
- Irrigation of involved sinuses
- Antifungal therapy - only if patient is high risk for invasive disease (very rare)
- Consider topical antifungal irrigation first and then systemic therapy if no improvement
Describe allergic fungal sinusitis
- Fungal colonization resulting in allergic inflammation without invasion
- IgE mediated response to fungal protein
Symptoms:
Nasal obstruction (gradual)
Rhinorrhea
Facial pressure/pain
Sneezing, watery/itchy eyes
Periorbital edema
What are the diagnostic criteria for allergic fungal sinusitis?
Diagnostic Criteria
- Eosinophlic mucin - pathognemonic
- Nasal polyposis
- Radiographic findings
- Immunocompetance
- Allergy to fungi
Charcot-Leyden crystals
What are the CT scan findings in allergic fungal sinusitis?
- Unilateral (78% of cases)
- Sinus expansion
- Bone destruction in 20% of cases (more often in advanced or bilateral disease)
- “Double Densities” - Heterogeneity of signal, increased heavy metal content (iron and manganese) and calcium salts
What is the treatment of allergic fungal sinusitis?
Surgical
- Remove all mucin
- Provide permanent drainage and ventilation of affected sinuses
Systemic +/- topical steroids
- Systemic steroids decrease rate of recurrence
- Course can range from 2-12 months
- 0.5mg/kg Prednisone starting dose and taper over 2-3 months
Immunotherapy
- decrease recurrence
- alleviate need for steroids
Describe acute fulminant invasive fungal sinusitis
Most often in immunocompromised (DM, AIDS, leukemia)
Most common fungi
- Aspergillus
- Mucormycosis (mucor, rhizopus, absidia)
Less common fungi
- Candida
- Bipolaris
- Fusarium
Describe the pathogenesis acute fulminant invasive fungal sinusitis
- Spores are inhaled, fungus grows in warm and humid sinonasal cavity
- Fungi invade neural and vascular structurs with thrombosis of vessels
- Necrosis and loss of sensation leads to acidic environment, further growth
- Extrasinus extension occurs via bony destruction, PNI, PVI
What are some clinical findings in acute fulminant invasive fungal sinusitis?
- Destruction of palate
- Facial anesthesia
- Proptosis
- CN deficits
- MS changes
- Fevers (most common)
- Ulceration of face
- Rhinorrhea
- Headaches
- Seizures
- Pale to black mucosa on endoscopy
- Death in hours to days!
What are the CT scan findings in acute fulminant invasive fungal sinusitis?
- Bone erosion and extrasinus extension – classic finding
- Severe, unilateral mucosal thickening
- Thickening of periantral fat planes
- Can involve cavernous sinsus
What is the treatment of acute fulminant invasive fungal sinusitis?
Medical
- Correct the underlying compromised state
- Reverse DKA and improve hydration
- 80% survival if done promptly
- Absolute neutrophil count (< 1000 = poor prognosis)
- WBC transfusion and granulocyte colony stimulating factor to increase ANC
- Amphotericin B (ototoxic, nephrotoxic)
- Voriconazole or itraconazole (Mucor is resistant to these)
Surgical
- Endoscopic in early course of disease
- Open in advanced disease
- Debride until bleeding margins
- Once intracranial, very high mortality
- Overall mortality 18-80%
- Mucromycosis = most fatal
Describe chronic invasive fungal sinusitis
- Slower disease process than acute
- Rare
- Biggest difference - Most patients are immunocompetent
Common fungi
- Aspergillus (most common at 80% of cases)
- Bipolaris
- Candida
- Mucormycosis