ESSENTIALS OF DIAGNOSIS
Most common cause of non-candidal invasive fungal infection in transplant recipients and in patients with hematologic malignancies.
Predisposing factors for invasive disease: leukemia, bone marrow or organ transplantation, corticosteroid use, advanced AIDS.
Pulmonary, sinus, and CNS are most common disease sites.
Detection of galactomannan in serum or other body fluids is useful for early diagnosis in at-risk patients.
Aspergillus fumigatus is the usual cause of aspergillosis, though many species of Aspergillus may cause a wide spectrum of disease. The lungs, sinuses, and brain are the organs most often involved. Clinical illness results either from an aberrant immunologic response or tissue invasion.
1. Allergic forms of aspergillosis—
Allergic bronchopulmonary aspergillosis (ABPA) occurs in patients with preexisting asthma or cystic fibrosis. Patients develop worsening bronchospasm and fleeting pulmonary infiltrates accompanied by eosinophilia, high levels of IgE, and IgG Aspergillus precipitins in the blood. Allergic aspergillus sinusitis produces a chronic sinus inflammation characterized by eosinophilic mucus and noninvasive hyphal elements.
2. Chronic aspergillosis—
Chronic pulmonary aspergillosis produces a spectrum of disease that usually occurs when there is preexisting lung damage but not significant immunocompromise. Disease manifestations range from aspergillomas that develop in a lung cavity to chronic fibrosing pulmonary aspergillosis in which the majority of lung tissue is replaced with fibrosis. Long-standing (longer than 3 months) pulmonary and systemic symptoms such as cough, shortness of breath, weight loss, and malaise are common.
3. Invasive aspergillosis—
Invasive aspergillosis most commonly occurs in profoundly immunodeficient patients, such as those who have undergone hematopoietic stem cell transplantation or have prolonged, severe neutropenia, but it can occur among critically ill immunocompetent patients as well. Specific risk factors in patients who have undergone a hematopoietic stem cell transplant include cytopenias, corticosteroid use, iron overload, cytomegalovirus disease, and graft-versus-host disease. Pulmonary disease is most common, with patchy infiltration leading to a severe necrotizing pneumonia. Invasive sinus disease also occurs. There is often tissue infarction as the organism grows into blood vessels; clues to this are the development of pleuritic chest pain and elevation of serum LD. At any time, there may be hematogenous dissemination to the CNS, skin, and other organs. Early diagnosis and reversal of any correctable immunosuppression are essential.
There is eosinophilia, high levels of total IgE, and IgE and IgG specific for Aspergillus in the blood of patients with ABPA.
For invasive aspergillosis, definitive diagnosis requires demonstration of Aspergillus in tissue or culture from a sterile site; however, given the morbidity of the disease and the low yield of culture, clinicians must maintain a high index of suspicion and use a combination of host, radiologic, and mycologic criteria ...