Page 199 - AIDSBK23C

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The follicular depletion pattern has absent follicles. The lymph node cortex is narrow or
undefined and the medulla occupies two thirds or more of the cross-sectional area. Small blood
vessels appear prominent due to decreased overall cellularity, and scattered histiocytes appear in
sinuses. Immunoblasts and/or plasma cells may be seen throughout the node. The depletion
pattern is the most commonly recognized pattern with AIDS at autopsy.[826,827,828]
Prior to the onset of clinical AIDS (in the stage of HIV infection previously known as
persistent generalized lymphadenopathy, as well as some cases of AIDS-related complex) the
lymph nodes throughout the body are large but usually do not exceed 3 cm in size and they may
vary in size over time. Most HIV-infected patients prior to onset of AIDS have follicular
hyperplasia, with or without follicular fragmentation, while almost 90% of AIDS patients have
follicular atrophy or depletion patterns. Though the lymph nodes in patients with AIDS can be
small, they are routinely enlarged from 1 to 2 cm. During the hyperplastic phase, germinal
centers contain predominantly CD19+ B-lymphocytes, which may account for
hypergammaglobulinemia. However, CD4 lymphocytes continue to decrease as a patient moves
from follicular hyperplasia to depletion.[826,827,828]
Antiretroviral therapy (ART) can suppress viral replication and lead to partial
reconstitution of the immune system. However, CD4 lymphocyte counts may not significantly
increase. Abnormalities in lymphoid architecture persist with ART. In one study, 89% of
lymphoid tissues showed abnormal T lymphocyte populations, 43% showed absence of follicles,
43% showed hyperplasia, and 14% showed regression.[829]

EXTRANODAL LYMPHOID TISSUES.-- Findings similar to those seen in lymph
nodes may occur in lymphoid tissues elsewhere in the body in patients with HIV infection.
Enlargement of nasopharyngeal and palatine tonsils may be associated with airway obstruction,
pharyngitis, and a visible mass lesion. Histologic changes are similar to HIV-related
lymphadenopathy, and the appearance of multinucleated giant cells is quite suggestive of HIV
infection.[830]

PEDIATRIC FINDINGS.-- Lymph node histopathologic changes with HIV infection in
children may differ from those in adults. Findings reported at autopsy, mostly in association
with deaths from AIDS, have included marked lymphocyte depletion, more selective follicular or
paracortical atrophy, hemophagocytosis, hyperplasia, and lymphadenitis. About half of cases
with lymphadenitis are due to an identifiable opportunistic infectious agent.[831]

MYCOBACTERIOSIS.-- Massive lymphadenopathy may indicate infection by
Mycobacterium avium complex (MAC). Mesenteric and retroperitoneal lymphadenopathy due
to MAC can demonstrate homogenous soft tissue attenuation by computed tomographic
scan.[416] If the involvement is extensive, a grossly lemon-yellow cut surface of lymph node,
similar in color to microbiologic culture plates, may be observed. Microscopically, MAC in
lymph node may be associated with sheets of foamy macrophages (so-called pseudo-Gaucher
cells), necrotizing granulomas, or non-necrotizing granulomas. In addition, a rare pseudotumor
pattern has a proliferation of fibroblast-like spindle cells in a storiform pattern, without vascular
slits but with abundant acid-fast bacilli, that is termed mycobacterial spindle cell pseudotumor.
The foamy macrophages can occur as single cells, small clusters, or large sheets with
hematoxylin-eosin staining and appear pale blue to striated. Wright-Giemsa stains can give these
macrophages the appearance of a Gaucher-like cell. Acid-fast stains best reveal the presence of