Acute pneumonia sometimes is evident on physical examination and chest x-ray. Progressive disseminated histoplasmosis follows hematogenous spread from the lungs that is not controlled by normal cell-mediated host defense mechanisms. Characteristically, generalized involvement of the reticuloendothelial system, with hepatosplenomegaly, lymphadenopathy, bone marrow involvement, and sometimes oral or GI ulcerations occurs, particularly in chronic cases. In general, the course is usually subacute or chronic, with only nonspecific, often subtle symptoms such as fatigue, weakness, malaise, or, in HIV-positive patients, an unexplained worsening in condition. Addison's disease is an uncommon but potentially serious manifestation and must be distinguished from other causes of adrenal insufficiency such as TB, sarcoidosis, lymphoma, or leukemia.
Severe manifestations occur most often in infants and immunocompromised patients.
Patients with AIDS may develop severe acute pneumonia with hypoxia suggestive of Pneumocystis carinii infection as well as hypotension, mental status changes, coagulopathy, or rhabdomyolysis. The manifestations are worsening cough and dyspnea, progressing eventually to disabling respiratory dysfunction. Dissemination does not occur. Another chronic but rare form of histoplasmosis is fibrosing mediastinitis, ultimately causing circulatory compromise. Diagnosis Culture of H. capsulatum from sputum, lymph nodes, bone marrow, liver biopsy, blood, urine, or oral ulcerations confirms the diagnosis.