Benign disorders of white cells II: lymphocytes, lymph nodes, spleen, HIV


Lymphocytosis occurs in viral infections, some bacterial infections (e.g. pertussis) and in lymphoid neoplasia. Lymphopenia (reduction in circulating lymphocytes to <1.5 × 109/L) occurs in viral infection (e.g. HIV), lymphoma, connective tissue disease, severe bone marrow failure and with immunosuppressive drug therapy. Lymphadenopathy is lymph node enlargement, which may be local or generalized. Causes are listed in Box 19.1.






Box 19.1 Causes of lymphadenopathy


Local

Localized bacterial/viral infection


Skin condition, e.g. trauma, eczema


Malignant – secondary carcinoma, lymphoma



General

Infection:



  • Bacterial, e.g. endocarditis, tuberculosis
  • Viral, e.g. HIV, infectious mononucleosis, cytomegalovirus
  • Other, e.g. toxoplasmosis, malaria

Malignancy


e.g. lymphoma, lymphoid leukaemias


Inflammatory disorders


e.g. sarcoidosis, connective tissue diseases


Generalized allergic conditions


e.g. widespread eczema





Infectious mononucleosis (glandular fever) is caused by Epstein–Barr virus (EBV) infection of B lymphocytes. Atypical circulating lymphocytes are reactive T cells. Cytomegalovirus, other viruses and Toxoplasma infections cause a similar blood picture (Fig. 19.1). Clinical features include onset usually in young adults (age 15–40 years), sore throat, lymphadenopathy, fever, morbilliform rash – particularly following treatment with amoxicillin – and jaundice, hepatomegaly and tender splenomegaly in a minority. Complications include autoimmune thrombocytopenia and/or haemolytic anaemia, myocarditis, neuropathy, encephalitis, hepatitis and postviral fatigue syndrome. The Paul–Bunnell test, modified as the monospot slide test (Fig. 19.2), detects heterophile antibodies (antibodies against cells of a different species). These agglutinate sheep or ox (bovine) red blood cells. The test is positive from 1 week after infection and persists for up to 2 months. Viral culture from sputum/saliva and specific IgM and IgG antibody tests against EBV nuclear and capsular antigens are sometimes useful in diagnosis.



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Jun 12, 2016 | Posted by in HEMATOLOGY | Comments Off on Benign disorders of white cells II: lymphocytes, lymph nodes, spleen, HIV

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