Diagnosis

Diagnosis

Acute invasive fungal rhinosinusitis.

Discussion

Acute invasive fungal rhinosinusitis (AIFR) is fungal infection of the paranasal sinuses and nasal cavity with vascular dissemination. AIFR is most commonly caused by Aspergillus spp. Other fungi like Rhizopus spp., Fusarium spp., Scedosporium, and dematiaceous fungi have also been implicated. Mixed fungal infections occur. Exposure to these organisms is typically by inhalation. Infection most commonly affects immunocompromised patients—for example, patients with diabetes, AIDS, malignant neoplasms with or without chemotherapy, and organ transplants.

As in the index case, rapid vascular dissemination of the causative fungi and fulminant tissue destruction may lead to spread of the infection beyond the sinonasal mucosa into the surrounding bone and even the brain. Fever, cough, nasal discharge, epistaxis, facial paresthesia, and headache are common presenting symptoms. AIFR is managed with surgical resection of infected tissue and antifungal medication.

AIFR is rapidly fatal in up to 50% of affected individuals. Early diagnosis and treatment are thus crucial to improving survival. Intraoperative frozen section analysis of the debrided tissue is often performed, as it is a rapid and diagnostically sensitive and specific test. In tissue sections, Aspergillus spp. appear as thin, septate acute angle branching hyphae. The fungi may also display vesicles with conidia (fruiting bodies). However, definitive speciation should be avoided as the morphology may overlap with that of other fungal species. Angioinvasion is demonstrated by the presence of organisms in vessel walls and is usually accompanied by thrombosis, extensive tissue necrosis, variable inflammatory reaction, and scattered calcium oxalate crystals.

Fungi are highlighted in tissue sections by PAS and GMS histochemical stains and fungal immunohistochemical stains. Further testing, such as fungal culture and PCR, should be carried out on portions of the intraoperative tissue specimen to speciate the fungi. However, unlike histology, non-histologic techniques cannot identify vascular invasion, and cannot distinguish between invasive infection, noninvasive disease, and noninfectious colonization.

References

Guarner J, Brandt ME. Histopathologic diagnosis of fungal infections in the 21st century. Clin Microbiol Rev. 2011;24(2):247-280. doi:10.1128/CMR.00053-10

Parikh SL, Venkatraman G, Delgaudio JM. Invasive Fungal Sinusitis: A 15-Year Review from a Single Institution. American Journal of Rhinology. 2004;18(2):75-81. doi:10.1177/194589240401800202
 

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