Case 1 -

Scedosporium Apiospermum Suzanne Z. Powell Weill Medical College of Cornell University The Methodist Hospital Houston, TX

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Discussion: Scedosporium apiospermum is a ubiquitous saprophytic filamentous fungus present in soil and contaminated waters, and is the asexual form of Pseudallescheria boydii. Invasive visceral infections of S. apiospermum usually occur in immuno-compromised hosts, especially in patients with solid organ transplant, hematological malignancy or bone marrow transplantation, and those with prolonged and severe granulocytopenia. Infections can be manifested as invasive sinusitis, pneumonia, arthritis with osteomyelitis, cutaneous and subcutaneous granulomata, meningitis, brain abscess, endophthalmitis and disseminated systemic disease. Recent cases have also been reported in near-drowning incidents, including tsunami survivors. In patients surviving near-drowning, fungal keratitis, lymphadenitis, brain abscess, endocarditis and lymphocutaneous lesions have been reported. Case 1 - Slide 1 Click to view with ImageScope Click to view with a Web-Based Viewer Case 1 - Slide 2 Click to view with ImageScope Click to view with a Web-Based Viewer Case 1 - Figure 1 - Pre-operative axial magnetic resonance FLAIR (fluid attenuation inversion recovery) image shows multiple mass lesions in the cerebral hemispheres bilaterally, including a large (4.5 cm diameter) mass of the right fronto-parietal region. Additional lesions were present in the corpus callosum and cerebellum. Case 1 - Figure 2 - Brain parenchyma with extensive acute inflammation and apoptosis/necrosis. (low magnification, H&E) Case 1 - Figure 3 - Brain parenchyma and vessels exhibiting necrosis, acute inflammation, fibrin deposition and hemorrhage. (intermediate magnification, H&E) Case 1 - Figure 4 - Blood vessel showing fibrinoid necrosis of the vascular wall. Close scrutiny of necrosing blood vessels at high-power revealed a rare fungal organism. (high magnification, H&E) Case 1 - Figure 5 - Scedosporium apiospermum. A GMS stain reveals angioinvasive fungal hyphae. (GMS stain for fungus) Case 1 - Figure 6 - Scedosporium apiospermum. High magnification showing branching septate hyphae. (GMS stain for fungus) Case 1 - Figure 7 - Scedosporium apiospermum. An additional high-magnification field showing branching septate hyphae. (GMS stain for fungus) Scedosporium apiospermum is an emerging fungal infection in patients treated for other fungal diseases including Aspergillosis. Histologically, the organism is a septate fungus with vasoinvasive features similar to Aspergillus. Therefore, fungal culture is necessary for differentiation of these organisms from one another and for confirmation of which organism is responsible for the infection. Early antifungal treatment and surgical intervention is the treatment of choice. However, common antifungal drugs (amphotericin B, fluconazole, and itraconazole) exhibit extremely low CSF concentrations. Voriconazole is the antifungal agent of choice for CNS infections caused by S. apiosperum because a CSF concentration of up to 50% that of the serum can be achieved. Posaconazole, ravuconazole and UR-9825 share a similar antifungal profile with voriconazole, and exhibit excellent in vitro effect against P. boydii-S. apiospernum. These epidemiologic factors are thus extremely important in the selection of an appropriate antifungal regimen and make culture confirmation all the more necessary. Pathologists must be wary of the similarities of this organism to Aspergillus on fungal stains and be cautious with the use of diagnoses such as "septate fungal hyphae consistent with Aspergillus species". The high overall mortality rate of Scedosporium apiospermum (58-75%) is reportedly associated with high fungal burden, as evidenced by dissemination, fungemia, and lack of recovery from neutropenia. Scedosporiosis remains relatively rare, but represents an emerging pathogen in transplant patients; selection of empiric therapy at the time of presentation may impact patient survival. References: Safdar A, Papadopoulos EB and Young JW. Breakthrough Scedosporium apiospermum (Pseudallescheria boydii) brain abscess during therapy for invasive pulmonary aspergillosis folllowing high-risk allogeneic hematopoietic stem cell transplantation. Scedosporiasis and recent advances in antifungal therapy. Transl Infect Dis 4:212-217, 2002. Kowacs PA, Siares-Silvado CE, Monteiro de Almeida S, Ramos M, Abrao K, Madaloso LE, Pinheiro RL, and Werneck LC. Infection of the CNS by Scedosporium apiospermum after near drowning Report of a fatal case and analysis of its confounding factors. 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Indian J Med Microbiol 24(3):231-232, 2006. Mursch K, Trnovec S, Ratz H, Hammer D, Horre R, Klinghammer A, de Hoog S, and Behnke-Mursch, J. Successful treatment of multiple Pseudoallescheria boydii brain abscesses and venticulitis/ependymitis in a 2-year ld child after a near-drowning episode. Hilds Nerv System 22:189-192, 2006. Maris, GA, Chamilos G, Lewis RE, Safdar A, Raad II, and Kontoyiannis DP. Scedosporium infection in a tertiary care cancer center: a review of 25 cases from 1989-2006. Clin Infect Dis 43:1580-1584, 2006. Marco de Lucas E, Sadaba P, Garcia-Baron PL, Ruiz-Delgado ML, Cuevas J, Salesa R, Bermudez A, GonzalezMandly A, Gutierrez A, Fernandez F, Marco de Lucas F, and Diez C. Cerebral scedosporiosis: an emerging fungal infection in severe neutropenic patients : CT features and CT pathologic correlation. Euro Radiol 16:496-502, 2006.