Which histologic findings are characteristic of fungal sinusitis?

Updated: Mar 17, 2020
  • Author: Hassan H Ramadan, MD, MSc; Chief Editor: Arlen D Meyers, MD, MBA  more...
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In allergic fungal sinusitis, allergic mucin contains intact and degenerated eosinophils, Charcot-Leyden crystals, cellular debris, and sparse hyphae. The sinus mucosa has mixed cellular infiltrate of eosinophils, plasma cells, and lymphocytes. The mucus membrane is not invaded by fungi.

No allergic mucin is present in sinus mycetoma. However, the sinus contains dense material that consists of hyphae separate from but adjacent to the mucosa. The sinus mucosa is not invaded.

Histopathologic studies in acute invasive fungal sinusitis reveal hyphal invasion of the mucosa, submucosa, and blood vessels, including the carotid arteries and cavernous sinuses; vasculitis with thrombosis; hemorrhage; and tissue infarction.

Necrosis of the mucosa, submucosa, and blood vessels, with low-grade inflammation, is observed in chronic invasive fungal sinusitis.

Granuloma with multinucleated giant cells with pressure necrosis and erosion is observed in granulomatous invasive fungal sinusitis.

A retrospective study by Melancon and Clinger indicated that in the diagnosis of acute invasive fungal sinusitis, frozen section biopsies have a positive predictive value of 100%, a sensitivity of 87.5%, and a specificity of 100% and are therefore important in the early diagnosis of this disease. [16]

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