Skin nontumor
Infectious disorders
North American blastomycosis
Author: Nat Pernick, M.D.
Last author update: 1 July 2011
Last staff update: 7 March 2024
Copyright: 2002-2024, PathologyOutlines.com, Inc.
PubMed Search: Fungi - North American blastomycosis [title]
Table of Contents
Definition / general | Clinical features | Diagnosis | Case reports | Treatment | Clinical images | Microscopic (histologic) description | Microscopic (histologic) images | Differential diagnosis | Additional referencesCite this page: Pernick N. North American blastomycosis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skinnontumorfungiblastomycosis.html. Accessed April 26th, 2024.
Definition / general
- Skin lesions usually secondary to pulmonary blastomycosis when soil containing mycelia is disturbed and airborne conidia are inhaled (Clin Microbiol Rev 2010;23:367); pulmonary disease may be subclinical
- Rarely occurs at site of penetrating injuries
- Due to Blastomyces dermatitidis, a spherical, double-contoured, 12 micron yeast that reproduces by budding
- Endemic areas are Mississippi, Missouri and Ohio river valleys (USA) and southern Canada
- Risk factors are immunosuppression, collagen vascular disease, being an outdoor worker, having a coworker with blastomycosis (Can J Infect Dis Med Microbiol 2009;20:117)
- May affect healthy patients via spore inhalation; usually men > women because they participate more in activities that disturb infected soil
Clinical features
- Slowly enlarging verrucous plaques containing multiple small abscesses
Diagnosis
- Histology, smears and culture using Sabouraud dextrose agar (Am J Surg Pathol 2010;34:256)
Case reports
- 53 year old African American man with diabetes and knee mass (Arch Pathol Lab Med 2005;129:e132)
Treatment
- Itraconazole or long term amphotericin
Clinical images
Images hosted on other servers:
Various images
Microscopic (histologic) description
- Marked pseudoepitheliomatous hyperplasia of epidermis
- Granulomatous and neutrophilic infiltrate
- Fungi are within giant cells
- Blastomyces dermatitidis is a 12 micron, spherical, double-contoured yeast with broad based buds
Microscopic (histologic) images
Images hosted on other servers:
Pseudoepitheliomatous hyperplasia, epidermal abscesses and prominent dermal infiltrate
High power shows fungal organisms
Budding yeast
Differential diagnosis
- Alternaria species: may have similar histologic features, but differentiate based on culture (J Cutan Pathol 2011;38:923)
- Squamous cell carcinoma: may resemble pseudoepitheliomatous hyperplasia of fungal infection, but has marked atypia and invasion
Additional references
