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Blastomycosis

Etiology: - infection with Blastomyces dermatitidis - late complication in patients with HIV1 infection/AIDS Epidemiology: 1) occurs in endemic & miniepidemic forms 2) miniepidemics have occurred in North Carolina, Minnesota & Illinois 3) most cases occur in southern, south central & Great Lakes states including Indiana 4) Mississipi River, Missouri River & Ohio River valleys 5) male:female ratio is 10:1 6) persons in contact with soil are more likely to be infected 7) infection acquired by inhalation of Blastomyces dermatitidis conidia Pathology: - involved organs include skin, nervous system, bone & joints, lungs, liver, spleen, kidney, prostate [2] - skin biopsy: pseudoepitheliomatous hyperplasia, intraepidermal neutrophilic abscesses,round yeast forms with broad-based budding [10] - rarely causes sepsis or intravascular catheter-associated infection except in severely immunosuppressed patients [2] Clinical manifestations: 1) manifests initially as pulmonary infection - 4-6 weeks after exposure - cough 2) sweating 3) nocturnal arthralgias 4) fever 5) vomiting [10] (case report) 6) subcutaneous nodules most common extrapulmonary manifestations a) verrucous lesions - generally on exposed skin - lesions non-pruritic (case report) [10] b) ulcerative lesions c) both verrucous & ulcerative lesions may occur in the same patient d) over time, skin lesions may undergo central clearing, scar formation & depigmentation 7) abscesses with draining sinuses 8) brain abscess or meningitis in patients with HIV1 infection/AIDS [2] * image of disseminated cutaneous blastomycosis [10] Laboratory: 1) Blastomyces dermatitidis antigen in urine (1st line) [12] 2) fungal stain microscopy of lesion - peripheral blood smear may show characteristic yeast forms with broad-based budding 3) culture of organisms from: a) pus (abscess drainage) b) bone marrow (systemic disease) c) sputum 4) serology: positive complement fixation test - Blastomyces dermatitidis Ab - unreliable, generally negative 5) Blastomyces dermatitidis rRNA 6) skin test is unreliable or unavailable Radiology: - chest X-ray a) perihilar mass that mimics carcinoma (most common finding) b) single, rounded opacity in upper lobe [9] c) pleural effusion (< 3%) Differential diagnosis: - histoplasmosis distinguished by hilar adenopathy & history of exposure to bat or bird dropping [2] - yeast forms of blastomycosis have a distinct appearance with broad-based budding Management: - itraconazole for mild to moderate disease a) response of skin lesions is good b) no indication for surgical excision of lesion [2] - duration of therapy: at least 6 month or until all signs & symptoms of disease are gone [2,4] - amphotericin B lipid formulation for severe pulmonary infection, disseminated disease or CNS infection [2] - itraconazole, voriconazole are alternatives for CNS infection - itraconazole, fluconazole are alternatives for skin infection, pulmonary infection [2]

Related

Blastomyces dermatitidis

General

mycosis; fungal infection

References

  1. DeGowin & DeGowin's Diagnostic Examination, 6th edition, RL DeGowin (ed), McGraw Hill, NY 1994, pg 869
  2. Medical Knowledge Self Assessment Program (MKSAP) 11, 15, 16, 17, 18, 19. American College of Physicians, Philadelphia 1998, 2009, 2012, 2015, 2018, 2021. - Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022
  3. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 808
  4. Chapman SW, Dismukes WE, Proia LA, Bradsher RW, Pappas PG, Threlkeld MG, Kauffman CA. Clinical Practice Guidelines for the Management of Blastomycosis: 2008 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2008, 46(12):1801-12 PMID: 18462107
  5. Smith JA, Kauffman CA. Blastomycosis. Proc Am Thorac Soc. 2010 May;7(3):173-80 PMID: 20463245
  6. Mansour MK, Ackman JB, Branda JA, Kradin RL. CASE RECORDS of the MASSACHUSETTS GENERAL HOSPITAL. Case 32-2015. A 57-Year-Old Man with Severe Pneumonia and Hypoxemic Respiratory Failure. N Engl J Med. 2015 Oct 15;373(16):1554-64. PMID: 26465989 http://www.nejm.org/doi/full/10.1056/NEJMcpc1503830
  7. Lopez-Martinez R, Mendez-Tovar LJ. Blastomycosis. Clin Dermatol. 2012 Nov-Dec;30(6):565-72. Review. PMID: 23068144
  8. Martynowicz MA, Prakash UB. Pulmonary blastomycosis: an appraisal of diagnostic techniques. Chest. 2002 Mar;121(3):768-73. PMID: 11888958
  9. NEJM Knowledge+ Question of the Week. April 17, 2018 https://knowledgeplus.nejm.org/question-of-week/
  10. Ladizinski B, Piette W Disseminated Cutaneous Blastomycosis. N Engl J Med 2018; 379:74. July 5 PMID: 29972741 https://www.nejm.org/doi/full/10.1056/NEJMicm1706238
  11. McBride JA, Gauthier GM, Klein BS. Clinical Manifestations and Treatment of Blastomycosis. Clin Chest Med. 2017 Sep;38(3):435-449 PMID: 28797487 Free PMC article. Review.
  12. Smith DJ, Free RJ, Thompson Iii GR et al. Clinical testing guidance for coccidioidomycosis, histoplasmosis, and blastomycosis in patients with community-acquired pneumonia for primary and urgent care providers. Clin Infect Dis 2023 Oct 6; [e-pub]. PMID: 37802909 https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciad619/7295325