aspergillosis

Aspergillus is a mold found in soil, decaying vegetation, and air, transmitted via inhalation of spores. Its clinical manifestations fall into several categories: (1) Allergic bronchopulmonary aspergillosis (ABPA) - a hypersensitivity reaction seen in asthma/cystic fibrosis patients, causing bronchiectasis, elevated IgE, and eosinophilia; (2) Aspergilloma ("fungus ball") - colonization of pre-existing lung cavities (e.g., from prior TB) without tissue invasion, can cause hemoptysis; (3) Invasive aspergillosis - occurs in severely immunocompromised hosts (neutropenia, prolonged corticosteroid use, hematologic malignancy, transplant recipients), causing angioinvasive pneumonia with hemoptysis, and can disseminate to brain, causing hemorrhagic infarcts. Histopathology shows septate hyphae with acute-angle (45°) branching, distinguishing it from Mucor (non-septate, wide-angle branching). Diagnosis involves galactomannan antigen testing, beta-D-glucan assay, CT chest showing "halo sign" (early invasive) or "air-crescent sign" (late/recovery), and culture/biopsy. Treatment: voriconazole is first-line for invasive aspergillosis; amphotericin B as alternative; surgical resection for aspergilloma. ABPA is treated with corticosteroids +/- itraconazole. High-yield boards association: aspergillosis in a neutropenic leukemia patient or after lung transplant presenting with pulmonary infiltrates and hemoptysis.