Laboratory Studies
- Cell culture
- Definitive diagnosis of sporotrichosis at any site requires the isolation of S schenckii in a specimen culture from a normally sterile body site.
- The organism can be recovered with fungal culture from sputum, pus, subcutaneous tissue biopsy, synovial fluid, synovial biopsy, bone drainage or biopsy, and cerebrospinal fluid (CSF).
- The concentration of organisms in synovial fluid and, particularly, CSF is often low. Therefore, repeated large-volume cultures may be necessary for diagnosis of sporotrichosis.
- Occasionally, S schenckii (cigar-shaped yeast) can be visualized in biopsied tissue specimens that are stained with periodic acid-Schiff, Gomori methenamine-silver, or immunohistochemical stains.
- Granulomatous inflammation is common; this is occasionally accompanied by the presence of an asteroid body, but this picture is not specifically diagnostic for sporotrichosis.
- Serological techniques
- Antibody measurement techniques are available.
- Such tests demonstrate significant interlaboratory variability in sensitivity and specificity; therefore, they should rarely serve as the sole basis for diagnosis of sporotrichosis.
- They can be useful to raise diagnostic suspicion and to inspire more aggressive attempts to acquire appropriate specimens for culture.
- The ratio of CSF to serum antibody titer may suggest the presence of sporotrichotic meningitis (CSF antibody titer higher than serum antibody titer).
- Polymerase chain reaction (PCR)–based techniques for diagnosis of sporotrichosis have been described but are not available for routine use.
Imaging Studies
- Radiography: Conventional radiographic imaging of the chest (in patients with suspected pulmonary sporotrichosis) and other involved areas (in patients with suspected osteoarticular sporotrichosis) is warranted but does not enable etiologic diagnosis. Chest CT scanning is supportive but not specifically diagnostic of sporotrichosis.
Procedures
- Arthrocentesis
- Patients with subacute or chronic arthritis should undergo diagnostic arthrocentesis.
- Sporotrichotic arthritis causes the general findings of an inflammatory arthritis (leukocytosis), with no crystals or growth on routine bacterial cultures.
- Synovial tissue biopsy: The diagnostic yield of synovial tissue biopsy for histology and culture is better than that of synovial fluid culture alone in patients with suspected sporotrichotic arthritis.
- Bone biopsy: Bone biopsy for histopathology and culture is useful and may be necessary for diagnosis of sporotrichal osteomyelitis.
- Full-thickness skin biopsy: Culture of exuded pus from cutaneous lesions can be diagnostic; however, full-thickness skin biopsy for histology and culture may improve diagnostic yield.
- Bronchoscopy with bronchoalveolar lavage for culture and transbronchial biopsy for histopathology may be required to establish the diagnosis of pulmonary sporotrichosis.
Histologic Findings
Sporotrichosis is characterized histopathologically by granulomatous inflammation with occasional asteroid bodies. The yeast form of the organism can be demonstrated, with considerable difficulty, in biopsy samples. See the image below.
Cigar-shaped yeast of Sporothrix schenckii in tissue macrophages in a biopsy specimen. Marimon R, Gene J, Cano J, et al. Molecular phylogeny of Sporothrix schenckii. J Clin Microbiol. Sep 2006;44(9):3251-6. [Medline].
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Winn RE. A contemporary view of sporotrichosis. Curr Top Med Mycol. 1995;6:73-94. [Medline].
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Silva-Vergara ML, Maneira FR, De Oliveira RM, et al. Multifocal sporotrichosis with meningeal involvement in a patient with AIDS. Med Mycol. Mar 2005;43(2):187-90. [Medline].
Freitas DF, de Siqueira Hoagland B, Do Valle AC, Fraga BB, de Barros MB, de Oliveira Schubach A, et al. Sporotrichosis in HIV-infected patients: report of 21 cases of endemic sporotrichosis in Rio de Janeiro, Brazil. Med Mycol. Aug 23 2011;[Medline].
Kauffman CA, Pappas PG, McKinsey DS, et al. Treatment of lymphocutaneous and visceral sporotrichosis with fluconazole. Clin Infect Dis. Jan 1996;22(1):46-50. [Medline].
Sharkey-Mathis PK, Kauffman CA, Graybill JR, et al. Treatment of sporotrichosis with itraconazole. NIAID Mycoses Study Group. Am J Med. Sep 1993;95(3):279-85. [Medline].
Chapman SW, Pappas P, Kauffmann C, et al. Comparative evaluation of the efficacy and safety of two doses of terbinafine (500 and 1000 mg day(-1)) in the treatment of cutaneous or lymphocutaneous sporotrichosis. Mycoses. Feb 2004;47(1-2):62-8. [Medline].
[Guideline] Kauffman CA, Bustamante B, Chapman SW, et al. Clinical practice guidelines for the management of sporotrichosis: 2007 update by the Infectious Diseases Society of America. Clin Infect Dis. Nov 15 2007;45(10):1255-65. [Medline]. [Full Text].
Lyon GM, Zurita S, Casquero J, et al. Population-based surveillance and a case-control study of risk factors for endemic lymphocutaneous sporotrichosis in Peru. Clin Infect Dis. Jan 1 2003;36(1):34-9. [Medline].
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