Disseminated histoplasmosis

Last revised by Joshua Yap on 16 Feb 2023

Disseminated histoplasmosis, also known as progressive disseminated histoplasmosis, is a severe form of histoplasmosis infection typically seen in immunosuppressed patients, especially in the setting of HIV infection. It results from hematogenous dissemination of the infection, involving multiple organs and systems and associating high mortality 1.

Although it is sometimes referred to as extrapulmonary histoplasmosis, lung involvement is one of the commonest manifestations of this condition 2.

Dissemination of the disease is fairly uncommon and may occur in 1 in 2000 acute infections 3.

Clinical presentation includes systemic symptoms such as fever, weight loss, and fatigue, and local systems depending on the organs involved, with frequent progressive shortness of breath and diarrhea 1,3.

Physical examination may reveal hepatosplenomegaly, lymphadenopathy, and skin and oral lesions 1.

  • lungs: parenchymal disease 2

  • bowel: any site of the digestive tube can be involved, with potential bleeding or perforation 1,4

  • liver and spleen: hemophagocytic lymphohistiocytosis with macrophage activation syndrome 1

  • kidneys: granulomatous nephritis 1

  • adrenal glands: adrenal insufficiency 1,3

  • central nervous system: meningeal, brain or spinal cord lesions 1

  • skin 1

Although multiple organs and systems can be affected, only thoracic and abdominal manifestations have been described in detail.

Chest radiographs show pulmonary abnormalities in about 50% of the patients 2. Diffuse multiple small nodules are the most common pattern, even though linear and irregular opacities or segmental, lobar or diffuse air-space opacities can also be observed 2,5.

CT demonstrates diffuse miliary nodules measuring 1-3 mm 3. Pleural effusions and thoracic lymphadenopathy are uncommon 2,3. Calcified lymph nodes or granulomas are described in about one-third of patients, indicating previous contact with the microorganism 2.

Central nervous system involvement occurs in 5-10% of patients, with focal mass-like lesions in the brain or the spinal cord with possible ring enhancement. Other less common features include meningitis, encephalitis, ischemic lesions, and hydrocephalus 1.

Initial treatment with liposomal amphotericin B is recommended in the first two weeks, followed by maintenance therapy with itraconazole for a minimum of 12 months 1,4.

Mortality without treatment reaches 80% but reduces to <25% when the appropriate drugs are administered 4.

For pulmonary involvement consider:

For hematologic involvement with hepatosplenomegaly and lymphadenopathy consider:

For gastrointestinal involvement consider:

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