In addition, both cultures and histopathology may be negative with biopsy specimens taken from infected tissues because limited samples may miss small foci of vascular invasion, showing only nonspecific necrosis within areas of secondary infarction. Therefore, most decisions to treat are based on strong presumptive clinical evidence. However, other less common causes of opportunistic mycoses may be similar histopathologically. Invasive sinusitis can be strongly suggested by CT scan and diagnosed by anterior rhinoscopy with confirmatory cultures and histopathology from biopsied necrotic lesions. Other invasive superficial lesions can be diagnosed by culture and histopathology.
Blood cultures are almost always negative, even with rare cases of endocarditis.
Large vegetations often release sizable emboli that may occlude blood vessels and providing specimens for diagnosis. Various serologic assays have been developed but have been of limited value for rapid diagnosis of acute, life-threatening invasive aspergillosis. Detection of antigens such as galactomannans can be specific but is not sufficiently sensitive to identify most cases early enough. Prognosis and Treatment Fungus balls neither require nor respond to systemic antifungal therapy but may require resection because of local effects, especially hemoptysis. Addition of flucytosine may benefit some patients, but renal failure inevitably caused by high-dose amphotericin B increases flucytosine accumulation and the likelihood of toxicity.