Wednesday, April 19, 2017
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Return to: Laryngeal leukoplakia white plaques on vocal cords

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Blastomyces dermatitidis, a soil saprobe found endemically in regions of the Mississippi and Ohio River Valleys, may rarely cause laryngeal leukoplakia. The inflammatory infiltrate that accompanies Blastomyces is usually granulomatous with a conspicuous mix of neutrophilic inflammation. Occasionally, the negative image of the yeast can be identified on H&E stain. A well-recognized pitfall is to mistake the pseudoepitheliomatous hyperplasia overlying the inflammation for well-differentiated squamous cell carcinoma. It is important to examine the submucosa of such biopsies for granulomas and evidence of infectious etiologies. Special stains are required for diagnosis. Yeast forms for Blastomyces range in size from 8 to 20 micrometers and bud with a broad base (4 to 10 micrometers) (McBride et al. 2017).

References

Hanson JM, Spector G, El-Mofty SK. Laryngeal blastomycosis: a commonly missed diagnosis. Report of two cases and review of the literature. Ann Otol Rhinol Laryngol. 2000 Mar;109(3):281-6. doi: 10.1177/000348940010900309. PMID: 10737312.

Rucci J, Eisinger G, Miranda-Gomez G, Nguyen J. Blastomycosis of the head and neck. Am J Otolaryngol. 2014 May-Jun;35(3):390-5. doi: 10.1016/j.amjoto.2013.12.013. Epub 2014 Jan 2. PMID: 24486126.

McBride JA, Gauthier GM, Klein BS. Clinical Manifestations and Treatment of Blastomycosis. Clin Chest Med. 2017 Sep;38(3):435-449. doi: 10.1016/j.ccm.2017.04.006. Epub 2017 Jun 12. PMID: 28797487; PMCID: PMC5657236.

Gallery
This biopsy shows a keratotic surface crust with a vaguely nodular submucosa expansion at low power. In this case, the abnormality appears to be going from the bottom up, rather than the top down, as is often observed with neoplasia.
An intermediate power view reveals a dense giant cell infiltrate with back to back epithelioid histiocytes and conspicious neutrophilic infiltrate
This high power view highlights the morphology of the histiocytes and enables one to see the negative image (arrows) of scattered yeast forms
Grocott Methenamine Silver (GMS) stain highlights several yeast that vary in size significantly. Blastomyces has some of the largest yeast forms (hollow arrows) and buds on a broad base (black arrow).
This low power view highlights pseudoepitheliomatous hyperplasia, a reactive phenomenon, overlying the submucosa inflammatory infiltrate. In some cases, this can mimic well-differentiated squamous cell carcinoma.
A high power view of pseudoepitheliomatous hyperplasia shows downward epithlelial growth with reactive nuclear changes and overall architectural regularity. A giant cells is shown (arrow).