What is the diagnostic approach for a patient with a 4-year history of nasal congestion, recently discovered mold exposure at home, and suspected chronic mold exposure in the sinuses and nasal passages?

Diagnostic Approach for Suspected Fungal Sinusitis

For a patient with chronic nasal congestion and suspected mold exposure, the diagnostic workup should begin with CT imaging of the paranasal sinuses without contrast, followed by nasal endoscopy with direct tissue biopsy and fungal staining, as histopathologic identification of fungal elements in sinonasal tissue is the gold standard for definitive diagnosis. 1

Initial Imaging

• CT of the paranasal sinuses without contrast is the optimal first-line imaging modality for suspected fungal sinusitis, as it demonstrates hyperattenuation in involved sinuses, bony erosions, and can detect fungal balls 1, 2
• CT is superior to plain radiographs, which have poor sensitivity and are inadequate for fungal sinusitis evaluation 1
• Hyperattenuation within sinuses on CT suggests fungal disease but is nonspecific; bone erosion and periantral fat infiltration have high specificity but limited sensitivity in early disease 1
• MRI should be added if invasive fungal sinusitis is suspected, as it better demonstrates soft-tissue invasion, orbital involvement, and intracranial extension, though it lacks the bony detail of CT 1, 2

Endoscopic Evaluation and Tissue Sampling

• Nasal endoscopy should be performed to directly visualize the sinus mucosa and obtain tissue specimens 2
• The middle meatus should be examined for purulent drainage, which can be collected using a calcium alginate swab or sinus aspirator 2
• Biopsy of diseased mucosa is essential for confirming fungal disease, determining if lesions are neoplastic, and identifying granulomatous disease 1, 2
• Tissue specimens should be sent for both histopathologic examination and fungal culture 2

Specialized Staining and Laboratory Testing

• Special fungal stains are required for tissue and secretion analysis, including Gomori methenamine silver or periodic acid-Schiff stains to identify fungal hyphae 2
• The distinction between invasive and non-invasive fungal rhinosinusitis depends on the presence or absence of fungal hyphae invading the mucosa 2
• Charcot-Leyden crystals and marked eosinophilia in secretions suggest allergic fungal sinusitis 2
• Fungal cultures should be obtained, though they provide supportive rather than definitive evidence; specimens should be sent to multiple laboratories if possible due to variable recovery rates 2
• PCR testing may be helpful if fungal elements cannot be detected by histopathology, though sensitivity remains limited (35% in one study) 2

Additional Diagnostic Tests

• Fungal-specific IgE testing and total serum IgE levels should be obtained if allergic fungal sinusitis is suspected 1
• Nasal cytology demonstrating eosinophils supports a diagnosis of allergic fungal sinusitis 1
• Gram stain and cytologic examination for eosinophils can provide rapid preliminary information 2

Critical Distinctions in Your Case

For a patient with 4 years of nasal congestion and home mold exposure, you are most likely dealing with non-invasive fungal colonization or allergic fungal sinusitis rather than invasive disease, as invasive fungal sinusitis occurs primarily in immunocompromised patients 1, 3. However, the diagnostic approach remains the same:

• Fungal colonization of the paranasal sinuses occurs in approximately 25% of patients with chronic sinusitis and represents commensal colonization rather than true mycosis in immunocompetent patients 4
• The most commonly isolated species in chronic sinusitis are Aspergillus fumigatus, Penicillium species, and Cladosporium species 4, 5
• Chronic hypertrophic sinusitis with increased mucus production impedes mucociliary clearance and facilitates fungal colonization 4

Important Caveats

• Do not delay imaging or endoscopy if the patient develops fever, orbital symptoms, or severe headache, as these may indicate progression to invasive disease even in immunocompetent hosts 1
• Do not rely on nasal vestibule or nasopharyngeal cultures, as these are unreliable due to contamination with resident microflora 2
• Histopathology alone has low sensitivity (<20%) for chronic invasive fungal disease, so negative histopathology does not exclude fungal involvement 2
• The mere presence of fungal DNA in mucus may not differentiate normal colonization from disease 2