51 HIV: reticulo-endothelial disorders

Common haematological abnormalities may lead to consideration of HIV as the cause. Direct effect of HIV itself or 2° to concurrent infection, malignancy, and therapeutic agents. Common findings are ↓ haemopoiesis, altered coagulation, and immune-mediated cytopenias with ↓ bone marrow cellularity and dysplasia.

Most common form of cytopenia and an independent prognostic factor. Usually due to ↓ erythropoiesis, but other mechanisms (e.g. infection, drug toxicity, malignancy, dietary deficiencies, alcohol abuse, blood loss) may contribute. Chronic anaemia causes fatigue, exertional dyspnoea, and a hyperdynamic state which, if severe, may lead to angina, congestive cardiac failure, and confusion.

Examine and test for iron, vitamin B₁₂, and folate deficiencies, haemolysis, and blood loss according to red cell indices. Eliminate possible causes by excluding infection and malignancy and reviewing drug therapy. Bone marrow examination may be required.

Occurs in up to 30%. May be result of drug toxicity, immune and non-immune destruction, or defective platelet production. Commonly an isolated haematological abnormality with ↑ levels of antiplatelet immunoglobulin. HIV-related immune thrombocytopenia is frequent early finding, tending to deteriorate as HIV progresses. Results from clearance of immunoglobulin-coated platelets by reticulo-endothelial system.

Exclude underlying causes, e.g. drug toxicity, liver disease, alcoholism, and lymphoma. In their absence the presence of normal or ↑ megakaryocytes on bone marrow examination is sufficient to diagnose HIV-induced thrombocytopenia.

Rare, of unknown aetiology, usually seen in early stages of HIV infection. Characterized by hyaline microvascular deposits. Clinical features include fever, renal impairment, neurological deficit, and microangiopathic haemolytic anaemia. Mortality rate ~65% without treatment. However, good response to plasmapheresis, steroids, HAART, and antiplatelets (e.g. aspirin).

HIV directly implicated, especially in advanced stages. More commonly due to drug toxicity, associated infection, and bone marrow infiltration. Risk of bacterial infection ↑ significantly when absolute neutrophil count <500cells/μL. Drugs causing neutropenia include AZT, ganciclovir, co-trimoxazole, pentamidine, α-interferon, and chemotherapeutic agents.

Careful review of medication. Withdraw offending drug(s) if absolute neutrophil count <500cells/μL. If cause uncertain, consider bone marrow examination.

↑ risk of thrombotic disease associated with low CD4 counts, OIs, neoplasms, and HIV-associated autoimmune disorders.

Generalized lymphadenopathy involving ≥2 extra-inguinal sites persisting for more than 3 months. Of no prognostic significance, but other causes of generalized lymphadenopathy should be excluded. Occurs in up to 70% of patients within 1 year of seroconversion but may coexist with other manifestations of HIV infection. Lymph nodes usually symmetrical, >1cm in size, rubbery, and non-tender. May be accompanied by hepatosplenomegaly. Mediastinal lymphadenopathy usually has other causes.