Pseudallescheriasis as an aggressive opportunistic infection in a bone marrow transplant recipient.

Pseudallescheria boydii is a low-virulence fungus that is the main causative agent of posttraumatic mycetoma in a nonimmunocompromised host. Immunocompromised patients are at high risk for locally invasive or disseminated Pseudallescheria infection. However, aggressive opportunistic infections due to P boydii are reported infrequently because it morphologically resembles other fungi, especially Aspergillus species, on tissue histology; therefore, such infections are not identified and treated properly. We report a case of disseminated P boydii infection in a patient following bone marrow transplantation. The identity of the fungus was not recognized until microbiologic culture results became available. Our case illustrates the importance of recognizing this fungus as an opportunistic infection in immunocompromised patients, as well as the need for culture of biopsy material for proper identification so that appropriate therapy can be instituted.