Renal Involvement

HIV itself may produce renal disease characterized by progressive renal failure, proteinuria, and diffuse enlargement of the kidneys which are hyperechoic on ultrasonography (Fig. 8.58B-D). Bacteria, including Mycobacterium tuberculosis and fungi may produce renal abscesses. Non-Hodgkins lymphoma may develop renal involvement, either by direct extension of adjacent adenopathy or by lymphoma intrinsic to the kidneys.

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Fig. 8.58 A-D. It is not always possible to identify the cause of the changes in AIDS patients. (A) An ulcer in the small intestine of a child with a history of gastrointestinal bleeding. This might be due to intimal fibrosis, similar to the vasculopathy seen in other groups in children with AIDS, or it might be caused by an unidentified infection. (B) in the kidney there are two patterns. There is an HIV-associated nephropathy which is a focal glomerulosclerosis with interstitial lymphocytic infiltration. This can be one of the presenting clinical symptoms of AIDS in children. In the other group of patients, the changes are nonspecific: there is renal enlargement and the underlying process may be direct HIV in origin. (C) The CT scan of an AIDS patient with diffusely enlarged kidneys due to AIDS nephropathy. (D) Ultrasonography of an enlarged kidney with increased echogenicity, the characteristic finding of AIDS nephropathy. (A and B from M.A. Greco and D. Zagzag, in D.H. Connor (ed): The Pathology of Infectious Diseases. Stamford, CT, Appleton and Lange, 1997, pp 169-181; C and D courtesy of Dr. William Brandt).

Ascites

The presence of ascites should raise the suspicion of tuberculosis, atypical mycobacteria, Kaposi's sarcoma, bacillary angiomatosis, or lymphoma. Pneumocystis carinii may produce ascites with peritoneal calcification.

Abdominal Lymphadenopathy

As previously noted, the presence of abdominal lymphadenopathy suggests lymphoma or tuberculosis (the latter more likely to be necrotic), atypical mycobacteria (often non-necrotic), Kaposi's sarcoma (mild contrast enhancement), or bacillary angiomatosis (dramatic contrast enhancement).

AIDS and the Cental Nervous System

AIDS produces a variety of neurological symptoms which may result in the patient being referred for imaging. About 30% of patients will have progressive dementia; CNS presentations also include headache, convulsions, meningeal signs, visual impairment, hemiplegia, focal seizures, and peripheral neuropathy. Meningitis, progressive rnultifocal leukoencephalopathy, cerebral lymphoma, toxoplasmosis, cryptococcosis, and mycobacterial, mycotic, or bacterial cerebral abscesses are common pathological conditions in AIDS. In Africa, focal neurological findings have been reported in about 10% of HIV-positive adult hospital admissions, and the AIDS dementia complex in 9%-54%. In the HIV-positive autopsies of Lucas and colleagues, 24% died primarily of intracerebral disease, and less than half had normal brains. Cerebral toxoplasmosis was the most common lesion, and this was 12 times more common than primary cerebral lymphoma, with which it can be confused on imaging studies. Tuberculous meningitis was the second most common intracerebral lesion in this study; other causes, of CNS pathology included, in descending order, pyogenic meningitis, cryptococcosis, cytomegaloviral encephalitis, and primary CNS lymphoma. In a study of meningitis in AIDS patients from the South African city,of Soweto, tuberculosis was also found to be the most common cause of meningitis, followed by bacterial meningitis (most commonly Streptococcus pneumoniae), viral meningitis, and cryptococcal meningitis.

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