For four months before death, this two-year-old black female infant ate poorly and lost weight. When hospitalized, she appeared chronically ill with signs of infection. An exploratory laparotomy showed the patient had enormously enlarged abdominal lymph nodes, the biopsy of which disclosed active histoplasmosis. Despite intensive therapy, the patient died three weeks after admission.
Autopsy showed widespread enlargement of lymph nodes, ulcers of the intestines, and enlarged adrenal glands exhibiting multifocal granulomas.
This is an even higher-power photomicrograph of an area of necrosis (arrows). There is loss of cellular detail within this area. There are inflammatory cells present; however, it is difficult to differentiate the inflammatory cells from the native lymphocytes of the adrenal gland--which is a lymph node.
Histoplasma capsulatum infection is usually acquired by inhalation of dust particles from soil contaminated with bird or bat droppings. The droppings contain small spores (microconidia).
1) A self-limited primary pulmonary involvement which may result in coin lesions on chest x-ray;
2) chronic, progressive, lung disease, which often localizes to the lung apices and causes cough, fever, and night sweats;
3) localized lesions in extrapulmonary sites, including mediastinum, adrenals, liver, or meninges; and
4) a widely disseminated involvement, particularly in immunosuppressed patients.
Histoplasma conidia and yeasts bind to the beta-chain of the integrins receptors LFA-1 (CD11a/CD18) and MAC-1 (CD11b/CD18).
Histoplasma yeasts are phagocytosed by the unstimulated macrophages, multiply within the phagolysosome, and lyse the host cells.
- de Pauw BE. Advances in the management of invasive fungal infections in organ transplant recipients: step by step. Transpl Infect Dis 2000 Jun;2(2):48-50.