Page 87 - Textbook of Pathology, 6th Edition

v) Appearance of self-limited non-specific acute viral illness Similarly, there are revised parameters for paediatric HIV 71
(flu-like or infectious mononucleosis-like) in 50-70% of adults classification in which age-adjusted CD4+ T cell counts are
within 3-6 weeks of initial infection. Manifestations include: given which are relatively higher in each corresponding
sore throat, fever, myalgia, skin rash, and sometimes, aseptic category.
meningitis. These symptoms resolve spontaneously in 2-3
weeks. PATHOLOGICAL LESIONS AND CLINICAL MANIFES- CHAPTER 4
2. Middle chronic phase (10-12 years). The initial acute sero- TATIONS OF HIV/AIDS. HIV/AIDS affects all body organs
conversion illness is followed by a phase of competition and systems. In general, clinical manifestations and
between HIV and the host immune response as under: pathological lesions in different organs and systems are
i) Viraemia due to viral replication in the lymphoid tissue owing to progressive deterioration of body’s immune system.
continues which is initially not as high but with passage of Disease Progression occurs in all untreated patients, even if
time viral load increases due to crumbling host defenses. the patient is apparently latent. Antiretroviral treatment
ii) Chronic stage, depending upon host immune system, blocks and slows the progression of the disease. Pathological
may continue as long as 10 years. lesions and clinical manifestations in HIV disease can be
iii) CD 4+ T cells continue to proliferate but net result is explained by 4 mechanisms:
moderate fall in CD4+ T cell counts. i. Due to viral infection directly: The major targets are immune
iv) Cytotoxic CD8+ T cell count remains high. system, central nervous system and lymph nodes (persistent
v) Clinically, it may be a stage of latency and the patient generalised lymphadenopathy).
may be asymptomatic, or may develop mild constitutional ii. Due to opportunistic infections: Deteriorating immune system
symptoms and persistent generalised lymphadenopathy. provides the body an opportunity to harbour micro- Immunopathology Including Amyloidosis
3. Final crisis phase. This phase is characterised by organisms. A list of common opportunistic infectious agents
profound immunosuppression and onset of full-blown AIDS affecting HIV/AIDS is given in Fig. 4.6.
and has the following features: iii. Due to secondary tumours: End-stage of HIV/AIDS is
i) Marked increase in viraemia. characterised by development of certain secondary malignant
ii) The time period from HIV infection through chronic tumours.
phase into full-blown AIDS may last 7-10 years and culminate iv. Due to drug treatment: Drugs used in the treatment produce
in death. toxic effects. These include antiretroviral treatment,
iv) CD 4+ T cells are markedly reduced (below 200 per μl). aggressive treatment of opportunistic infections and
The average survival after the onset of full-blown AIDS tumours.
is about 2 years. Based on above mechanisms, salient clinical features and
Children often have a rapidly progressive disease and pathological lesions in different organs and systems are
full blown AIDS occurring at 4 to 8 years of age. briefly outlined below and illustrated in Fig. 4.6. However,
it may be mentioned here that many of the pathological
REVISED CDC HIV CLASSIFICATION SYSTEM. The lesions given below may not become clinically apparent
Centers for Disease Control and Prevention (CDC), US in during life and may be noted at autopsy alone.
1993 revised the classification system for HIV infection in
adults and children based on 2 parameters: clinical mani- 1. Wasting syndrome. Most important systemic
festations and CD4+ T cell counts. According to this classi- manifestation corresponding to body’s declining immune
fication, HIV-AIDS has 3 categories: A, B and C (Table 4.5). function is wasting syndrome defined as ‘involuntary loss
of body weight by more than 10%’. It occurs due to multiple
Category A: Includes a variety of conditions: asymptomatic
case, persistent generalised lymphadenopathy (PGL), and factors such as malnutrition, increased metabolic rate,
acute HIV syndrome. CD4+ T cell counts in clinical category malabsorption, anorexia, and ill-effects of multiple
A are >500/μl. opportunistic infections.
Category B: Includes symptomatic cases and includes 2. Persistent generalised lymphadenopathy. In early
conditions secondary to impaired cell-mediated immunity asymptomatic stage during the course of disease, some
e.g. bacillary dysentery, mucosal candidiasis, fever, oral hairy patients may develop persistent generalised lymphadeno-
leukoplakia, ITP, pelvic inflammatory disease, peripheral pathy (PGL). PGL is defined as presence of enlarged lymph
neuropathy, cervical dysplasia and carcinoma in situ cervix nodes >1 cm at two or more extrainguinal sites for >3 months
etc. CD4+ T cell counts in clinical category B are 200-499/μl. without an obvious cause. There is marked cortical follicular
hyperplasia, due to proliferation of CD8+ T cells, B cells and
Category C: This category includes conditions listed for AIDS dendritic follicular histiocytes. HIV infected CD4+ T cells are
surveillance case definition. These are mucosal candidiasis, seen in the mantle zone. In advanced cases of AIDS, lymph
cancer uterine cervix, bacterial infections (e.g. tuberculosis), nodes show progressive depletion of lymphoid cells, or there
fungal infections (e.g. histoplasmosis), parasitic infections may be occurrence of opportunistic infection (e.g. M. avium
(e.g. Pneumocystis carinii pneumonia), malnutrition and intracelluare, Histoplasma, Toxoplasma) or appearance of
wasting of muscles etc. CD4+ T cell counts in clinical category secondary tumours in the lymphoid tissue (e.g. Kaposi’s
C are <200/μl and are indicator for AIDS. sarcoma, lymphoma).