Page 152 - AIDSBK23C

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Accompanying LIP may be a pattern of pulmonary lymphoid hyperplasia (PLH) that is
characterized by lymphoid follicles with or without germinal centers that often surround
bronchioles. The most florid form of lymphoid hyperplasia involving lung is seen in HIV-
infected children and is known as polyclonal B-cell lymphoproliferative disorder (PBLD). With
PBLD there are nodular infiltrates of polyclonal B-lymphocytes and CD8+ T-lymphocytes.
Other organs may also be involved by PBLD.[646]

NONSPECIFIC INTERSTITIAL PNEUMONITIS.-- About 1 in 10 bronchoscopic
biopsies in adult AIDS patients reveals the presence of an interstitial pneumonitis with
lymphocytic infiltrates, but no identifiable organisms. It may represent a Mycoplasma or viral
pneumonitis, such as influenza, without diagnostic pathologic features. A careful search for viral
inclusions should be made, in addition to performance of histologic stains for fungi,
mycobacteria, and Pneumocystis jiroveci (carinii). Sometimes, only multinucleated cells
suggestive of viral effect are found. Multiple viral serologic studies are often not useful.
Clinically, non-specific interstitial pneumonitis mimics Pneumocystis pneumonia or lymphocytic
interstitial pneumonitis. Thus, not all cases of pneumonitis in AIDS have a definable cause
despite an extensive search for etiologies. Though lymphoid aggregates may be present, the
lymphocytic infiltrates of nonspecific, or chronic, interstitial pneumonitis tend to be less
extensive than those of lymphoid interstitial pneumonitis and restricted to peribronchiolar,
perivascular, paraseptal, and pleural regions. Clinically, patients with nonspecific interstitial
pneumonitis often have a normal chest roentgenogram.[645]

MISCELLANEOUS PULMONARY LESIONS IN AIDS.-- The pulmonary interstitium
may show small foreign body granulomata with needle-shaped crystalline material that is
birefringent under polarized light in patients with a history of injection drug use. Only rarely are
these granulomata visible as 0.1 to 0.3 cm pale tan nodules. Rarely are they accompanied by
extensive interstitial fibrosis.[647]
When patients with AIDS receive antiretroviral therapy and are diagnosed and treated for
opportunistic infections of the lungs, their survival is increased. However, increasing survival
with multiple, recurrent, and prolonged bouts of infections results in a greater incidence of
bronchiectasis. Bronchiectasis in association with AIDS is most often seen following recurrent
pyogenic infections.[607,648]
Pulmonary arterial hypertension (PAH) is not common but appears with increased
frequency in association with HIV infection and AIDS. Clinically HIV-PAH resembles cases of
primary or idiopathic pulmonary hypertension in non-HIV-infected patients. Unlike familial
PAH, it is not associated with mutations in the bone morphogenetic protein type 2 receptor
(BMPR2). Reported risk factors include intravenous drug abuse and viral hepatitis. Most
patients have a CD4 lymphocyte count above 200/µL and an undetectable viral load in peripheral
blood. Patient findings can include progressive shortness of breath, pedal edema, dry cough,
fatigue, syncope, and chest pain. Chest x-ray may show cardiomegaly and prominent pulmonary
arteries. An electrocardiogram may show right ventricular hypertrophy. On cardiac
catheterization the pulmonary arterial systolic pressure, diastolic pressure and pulmonary
vascular resistance are increased.[649,650]
The histopathologic findings in HIV-PAH include pulmonary arteriopathy with medial
hypertrophy, intimal thickening and/or plexiform lesions (89%), with veno-occlusive disease in
7% and thrombotic pulmonary arteriopathy in 4%. Treatment regiments may include use of