Page 251 - AIDSBK23C

Page 251

BONE, JOINT, AND SOFT TISSUE PATHOLOGY IN AIDS

The skeletal system and supporting structures including bone, cartilage, tendons, and
ligaments do not have specific lesions related to HIV infection and its sequelae.. A painful
articular syndrome with HIV infection is characterized by severe articular pain from a few hours
to 24 hours and associated with significant disability, resulting in many of the patients presenting
to an emergency room or being hospitalized. However, there are no signs of inflammation on
physical examination. The joints most frequently involved with painful articular syndrome are
the knees, shoulders and elbows.[1020]
Rheumatologic abnormalities may accompany HIV infection. HIV and its proteins,
particularly viral envelope proteins, may have some homology with HLA antigens, Fas protein,
and immunoglobulins. Thus, there may be autoantibodies and autoimmune responses. Several
nonspecific rheumatologic manifestations have been noted with HIV infection, particularly prior
to use of high active antiretroviral therapy (ART). One such manifestation is arthralgia alone,
oligoarticular in 54.3% of cases, monoarticular in 11.4% and polyarticular in 34.3%, and the
joints most frequently involved are the knees (51%), followed by the shoulders (29%) and
elbows (26%). Additional manifestations may include reactive arthritis, Reiter syndrome,
psoriatic arthritis, polymyositis, and classic polyarteritis nodosa.[1021]
The rheumatologic clinical presentations in some AIDS patients may resemble systemic
lupus erythematosus (SLE). These findings can include arthralgias, myalgias, and autoimmune
phenomena including a low titer positive antinuclear antibody, coagulopathy with lupus
anticoagulant, hemolytic anemia, and thrombocytopenic purpura. Hypergammaglobulinemia
from polyclonal B-cell activation may be present, but often diminishes in the late stages of
AIDS. Specific autoantibodies to double-stranded DNA, Sm antigen, RNP antigen, SSA, SSB
and other histones may be found in a majority of HIV-infected persons, but their significance is
unclear. Other rheumatologic manifestations include vasculitis, fibromyalgia, and
spondyloarthropathy.[1022] Similar autoantibodies have also been reported in children with
HIV infection.[1023] Mixed cryoglobulinemia may be detected in persons with HIV infection,
and the HIV-1 viral load tends to be higher in such persons, which may lead to antigenic
stimulation that drives polyclonal B lymphocyte activation.[1024]
An HIV-associated arthritis has been described that is a predominately lower extremity-
occurring oligoarthritis that can occur anytime in the course of HIV. The pattern of joint
involvement can vary, with some patients presenting in a rheumatoid-arthritis-like distribution.
This condition tends to be self-limited, but can cause significant joint destruction. Laboratory
analysis of synovial fluid shows a low cell count, while serum HLA-B27, antinuclear antibody,
and rheumatoid factor are usually negative.[1020]
Septic arthritis is most likely to occur in HIV-infected patients whose risk factor is
injection drug use. Staphylococcus aureus and streptococci are the most commonly cultured
organisms. There is no correlation with CD4 lymphocyte counts.[1020,1021]
Kaposi sarcoma (KS) rarely involves bone in patients with AIDS, and the axial
(vertebrae, ribs, sternum, and pelvis) and/or maxillofacial bones are most likely to be involved.
These patients typically have KS elsewhere. Joint and muscle involvement by KS are rare. The
lesions tend to be small, without pathologic fractures, and radiographs have poor sensitivity for
detection, while CT and MR imaging are better at detecting the osteolytic lesions.[1025]