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168 Aspergillosis➣Basic studies: culture
Important for definitive diagnosis of invasive disease together
with histopathology
➣Other studies: serology
Antibodies to Aspergillus traditionally not helpful in diagnosis
of invasive disease
However, precipitating antibodies to Aspergillus antigen a cri-
terion in diagnosis of ABPA EIA, ELISA and immunoblot meth-
ods may show promise in the future
Galactomannan – carbohydrate component of Aspergillus
cell wall. FDA-approved antigen assay in serum. Sensitivity 81–
94%, specificity 84–99% depending on cutoff values used. Use-
ful as adjunct to clinical, radiologic, and microbiologic findings
but does not replace these.Imaging
■CXR:
➣Late findings include cavities or wedge-shaped pleural-based
densities for invasive pulmonary disease.
■CT:
➣May precede CXR findings
➣A “halo sign” is an early sign, seen as a pulmonary nodule sur-
rounded by an area of low attenuation; may be caused by bleeding
or edema surrounding an area of ischemia.
➣The “crescent sign” is a later sign referring to lung tissue that
has infarcted and contracted around a nodule, leaving an air
crescent.differential diagnosis
■Histopathologically, Aspergillus hyphae are very difficult to dis-
tinguish from Pseudallescheria boydii, Fusarium and some other
molds.
■Culture is key to confirm the histopathologic appearance in tis-
sue because treatment may be different depending on the mold
isolated.management
What to Do First
■First assess risk factors for invasive disease: neutropenia, prolonged
use of corticosteroid and other immunosuppressive therapy, bone
marrow or solid organ transplant patient.