Thoracic Imaging 2003 - Society of Thoracic Radiology

THURSDAY
254
AIDS patients are also at an increased risk of developing
both endemic and opportunistic fungal infections with the manifestations
dependant on the patient’s immune status. In the New
York City area we see reactivation of the endemic fungus histoplasmosis,
usually in the disseminated form, in severely
immunocompromised patients who have emigrated from endemic
areas. The most common chest radiographic and CT findings
are innumerable small nodules-usually slightly larger than military
nodules-with or without associated lymphadenopathy. The
most common opportunistic fungal infection in AIDS patients is
cryptococcus. Cryptococcal meningitis is seen more commonly
than cryptococcal pulmonary disease, but the lung is the second
most frequently involved organ. It can be involved in isolation,
or as a manifestation of disseminated disease. The chest radiographic
and CT findings of cryptococcal pulmonary disease in
AIDS are varied. Diffuse small nodules can be seen-similar to
histoplasmosis. However, single or multiple larger nodules or
masses with or without cavitation, pleural effusions and lymphadenopathy
are all manifestations of cryptoccus in AIDS.
Clinical and radiographic findings in AIDS patients with cryptoccal
infection also can worsen on HAART. Thus cryptoccus
falls within the spectrum of diseases of immune restoration or
reconstitution.
Sarcoidosis, which is of unknown etiology has also been
observed to develop or worsen on HAART and is one of the
thoracic manifestations of immune reconstitution syndrome.
Aspergillus infection, which occurs with some frequency in
solid organ and bone marrow transplant patients can occur in
late stage AIDS, but is seen infrequently. Host defense against
aspergillosis is neutrophil and macrophage activity rather than
cellular immunity, while diminution of cellular immunity is the
hallmark of HIV-infection. Therefore, additional factors come
into play when AIDS patient develop aspergillosis. They may
be treated with medication that suppresses bone marrow, or be
at an extreme end stage of their disease with diminished neutrophil
function. Although aspergillus is a ubiquitous organismpresent
in the soil- it is reported that marijuana often contains a
large amount of aspergillus. Smoking marijuana in a weakened
state of immunity can lead to inhalation of a large bolus of
aspergillus organisms and consequent infection. When AIDS
patients develop aspergillosis, the most common form is semiinvasive
disease. Other forms include invasive and bronchial
aspergillosis. The chest radiographic and CT manifestation of
aspergillosis include ill-defined nodules or infiltrates, thickwalled
cavities with dependant soft tissue masses and bronchial
abnormalities. Hemoptysis is a dreaded consequence.
Viral infections are often difficult to document in HIV-infection,
as in other clinical settings. In the lung, the most commonly
documented viral infection is with cytomegalovirus
(CMV). These patients are usually severely immunocompromised
with CD4