Introduction: Infection with Scedosporium apiospermum (anamorphic form also known as Pseudallscheria boydii, the sexual or telomorphic form) produced a spectrum of disease similar in terms of variety and severity to those caused by Aspergillus. The vast majority of infections are mycetomas, the remainder include infections of the eye, ear, central nervous system, internal organs and more commonly the lungs. Infections result from either inhalation of air-borne conidia or by the traumatic implantation of fungal elements due to a penetrating injury.

The organism: Scedosporium sp. are classified with the agents of hyalohyphomycosis. They produce single, large (4-9 um) lemon-shaped or pyriform conidia. The conidia are borne usually singly from a simple or branched conidiophore. The cleistothecia, baglike structures which contain sexually derived spores called ascospores, are observed only in the telomorphic form Pseudoallscheria boydii.

Clinical manifestations: Non-invasive colonization of the external ear and pulmonary colonization in patients with poorly draining bronchi or paranasal sinuses and "fungus ball" formation in pre-formed cavities are similar to those seen in Aspergillus. Colonization has been reported in patients with cystic fibrosis, which is most consistent with this care.

Invasive infections in normal patients are usually caused by traumatic implantation. Mycetoma, where the fungus exists in tissue as resistant microcolonies or grains is the most common infection in the normal patient. This is followed by penetrating joint injuries, especially to the knee, resulting in arthritis and osteomyelitis. Other manifestations include mycotic keratitis and non-mycetoma like cutaneous and subcutaneous infections. Invasive infections have also been reported in patients receiving treatment with corticosteroids and immunosuppressive therapy for organ transplantation, leukemia, lymphoma, systemic lupus erythematous or Crohn's disease. Infections include invasive sinusitis, pneumonia, arthritis with osteomyelitis, cutaneous and subcutaneous granulomata, meningitis, brain abscesses, endophthalmitis, and disseminated systemic disease.

Laboratory diagnosis: Direct microscopy of sputum, washings, and aspirates via wet mounts in 10% KOH and Parker in or Calcofluor and/ or Gram stained smears will reveal hyphal elements (branched, septate) that are histologically indistinguishable from those of Aspergillus and can easily be missed on H&E stained sections. Culture in necessary for a specific identification of the causative agent, and is the only means of distinguishing it from Aspergillus species. Colonies are fast growing and are greyish-white, to olive-grey to black with a suede-like to downy surface texture. S. apiospermum common soil fungi, therefore a positive culture from a non-sterile specimen, such as sputum or skin, needs to be supported by direct microscopic evidence in order to be considered significant. A positive culture from a biopsy or aspirated material from a sterile site should be considered significant.