Clinical and Laboratory Update on Blastomycosis

Abstract

SUMMARY Blastomycosis is endemic in regions of North America that border the Great Lakes and the St. Lawrence River, as well as in the Mississippi River and Ohio River basins. Men are affected more often than women and children because men are more likely to participate in activities that put them at risk for exposure to Blastomyces dermatitidis. Human infection occurs when soil containing microfoci of mycelia is disturbed and airborne conidia are inhaled. If natural defenses in the alveoli fail to contain the infection, lymphohematogenous dissemination ensues. Normal host responses generate a characteristic pyogranulomatous reaction. The most common sites of clinical disease are the lung and skin; osseous, genitourinary, and central nervous system manifestations follow in decreasing order of frequency. Blastomycosis is one of the great mimickers in medicine; verrucous cutaneous blastomycosis resembles malignancy, and mass-like lung opacities due to B. dermatitidis often are confused with cancer. Blastomycosis may be clinically indistinguishable from tuberculosis. Diagnosis is based on culture and direct visualization of round, multinucleated yeast forms that produce daughter cells from a single broad-based bud. Although a long course of amphotericin B is usually curative, itraconazole is also highly effective and is the mainstay of therapy for most patients with blastomycosis.

Treatment of chronic pulmonary blastomycosis with caspofungin

“…If left untreated, chronic blastomycosis is associated with significant mortality. For these reasons, some authors recommend that all patients with chronic pulmonary blastomycosis receive antifungal therapy (Bradsher & Bariola, 2011;Saccente & Woods, 2010). In our patient, there were no signs of improvement after at least 3 months of disease, hence our decision to begin treatment.…”

“…Nevertheless, there have been well-documented cases of acute exacerbations, development of chronic disease, relapse or haematogenous dissemination to various organs if left untreated (Bradsher, 1996). Furthermore, it is impossible to predict which patients will spontaneously recover, which explains why many physicians decide to treat these cases (Saccente & Woods, 2010).…”

Atypical Cutaneous Blastomycosis in a Child With Juvenile Idiopathic Arthritis on Infliximab

“…Human infection typically occurs when soil containing the Blastomyces conidia are inhaled; classically, this manifests as primary pulmonary disease with constitutional symptoms of fever, cough, and fatigue but may be asymptomatic. 3 When natural alveolar defenses fail to contain the infection, hematogenous dissemination ensues, affecting 25% to 30% of patients. 8 The most common extrapulmonary sites of disease include the skin, bone, genitourinary, reticuloendothelial, and central nervous systems.…”

“…8 The most common extrapulmonary sites of disease include the skin, bone, genitourinary, reticuloendothelial, and central nervous systems. 1,3,8 Morphologically, cutaneous blastomycosis typically presents in either verrucous or ulcerative forms. Verrucous lesions begin as papules that evolve into crusted, warty plaques with an irregular shape, sharp borders, and central clearing.…”

“…Lesion morphology is classically verrucous or ulcerative in nature. 3 The differential diagnosis of cutaneous blastomycosis includes tuberculosis, disseminated mycobacterial infections, other deep fungal infections, cutaneous leishmaniasis, halogenodermas, pyoderma gangrenosum, squamous cell carcinoma, and sarcoidosis. 4 Iatrogenic immunosuppression is a known risk factor the development of fungal infections.…”