Acquired Immunodeficiency Syndrome (AIDS)
When the CD4 lymphocyte count drops below 200/microliter, then the stage of
clinical AIDS has been reached. This is the point at which the characteristic
opportunistic infections and neoplasms of AIDS appear. Listed below are
some of the more common complications seen with AIDS with images that
illustrate gross and microscopic pathologic findings.
The organ involvement of infections with AIDS represents the typical
appearance of opportunistic infections in the immunocompromised host--that
of an overwhelming infection--that makes treatment more difficult. The
strategies employed in AIDS patients to meet this challenge consist of (1)
preserving immune function as long as possible with antiretroviral therapies,
(2) using prophylactic pharmacologic therapies to prevent infections (such as
Pneumocystis jiroveci pneumonia), and (3) diagnosing and treating acute
infections as soon as possible.
Pneumocystis jiroveci
Pneumocystis jiroveci (formerly carinii) is the most frequent opportunistic
infection seen with AIDS. It commonly produces a pulmonary infection but
rarely disseminates outside of lung. The most frequent clinical findings in
patients with pneumonia are acute onset of fever, non-productive cough, and
dyspnea. Chest radiograph may show perihilar infiltrates. Diagnosis is made
histologically by finding the organisms in cytologic (bronchoalveolar lavage) or
biopsy (transbronchial biopsy) material from lung, typically via bronchoscopy.
The cysts of P jiroveci stain brown to black with the Gomori methenamine
silver stain. With Giemsa or Dif-Quik stain on cytologic smears, the dot-like
intracystic bodies are seen.