Page 137 - AIDSBK23C

Page 137

CHAPTER 5 - ORGAN SYSTEM PATHOLOGY IN AIDS

RESPIRATORY TRACT PATHOLOGY IN AIDS

Patients with HIV infection frequently present with a wide spectrum of pulmonary
complications from opportunistic infections and neoplasms that may be associated with a high
mortality rate. Diseases of the respiratory tract account for many deaths from AIDS.[417] The
response to therapy in AIDS can be slower and complicated by a greater number of adverse
reactions to therapeutic agents than with other immunocompromised states. Cigarette smoking
increases the risk for colonization by infectious agents, and smoke decreases alveolar
macrophage function, leading to increased numbers of infections or more severe infections.[598]
Cigarette smoking has been shown to be an independent risk factor for non-AIDS related
mortality in persons infected with HIV. Cigarette smoking has also been reported to reduce the
quality of life in this population as well.[599] The clinical features of many pulmonary diseases
in AIDS are similar, necessitating serologic, culture, tissue, or cytologic diagnosis. Table 5
indicates the distribution of AIDS-diagnostic diseases in the respiratory tract seen at autopsy.
Table 8 details the typical patterns of involvement.

PNEUMOCYSTIS JIROVECI (CARINII) PNEUMONIA (PCP).-- PCP is one of the most
frequent and severe opportunistic infections in patients with AIDS.[402] Many AIDS patients
will have at least one episode of PCP at some point during their clinical course, with mortality
from a single episode ranging from 10 to 30%. However, use of antipneumocystis therapy and
prophylaxis, either with trimethoprim-sulfamethoxazole, dapsone, or aerosolized pentamidine,
can greatly diminish the incidence of PCP and increase survival.[208] The more extensive use of
these therapies has increased survival for AIDS patients in places where it has been applied, both
in the short term following a bout of PCP and in the first two years following diagnosis of
AIDS.[600] Smoking increases the risk for PCP.[601]
Clinical features that suggest a high risk for PCP include oral thrush or unexplained
fever. Clinical features with PCP that predict a poor prognosis include long duration of
symptoms (weeks), prior episodes of PCP, prior therapy with antibiotics other than
trimethoprim-sulfamethoxazole, older age, and presence of cytomegalovirus.[602,603]
Clinical features of PCP typically include the classic triad of fever, non-productive
cough, and dyspnea, each of which may be present in 3/4 to 2/3 of cases, but together in less than
half of cases. A pleuritic type of chest pain may also be present. A pleural effusion may
accompany PCP. Spontaneous pneumothorax is an uncommon complication that can recur and
be difficult to treat.[604] In general, the duration of these symptoms in a patient with AIDS is
longer than that for patients without AIDS. Elevation of the serum lactate dehydrogenase (LDH)
is highly sensitive for the diagnosis of PCP, but not specific because other pulmonary diseases
such as tuberculosis and bacterial pneumonia may also have an elevated LDH, as well as
extrapulmonary disorders. An elevated beta-D-glucan level in the serum suggests the diagnosis
of PCP.[598,605]
Pneumocystis jiroveci (carinii) typically produces a pneumonia that is widespread
throughout the lungs. P jiroveci (carinii) pneumonia is a chronic disease that often responds
well to drug treatment. However, there can also be rapid progression leading to adult respiratory