Toxoplasma Lymphadenitis



Toxoplasma Lymphadenitis


Carlos E. Bueso-Ramos, MD, PhD










Toxoplasma lymphadenitis. Note enlarged follicles with reactive germinal centers, clusters of epithelioid cells encroaching on lymphoid follicles, and monocytoid cells.






Hematoxylin and eosin stain shows a reactive germinal center with many centroblasts, tingible-body macrophages, and epithelioid cells encroaching into the germinal center from the right image.


TERMINOLOGY


Synonyms



  • Toxoplasmic lymphadenitis


  • Glandular toxoplasmosis


  • Piringer-Kuchinka lymphadenopathy


Definitions



  • Inflammation of lymph node caused by infection by Toxoplasma gondii


ETIOLOGY/PATHOGENESIS


Toxoplasma gondii Infection



  • T. gondii is protozoan that can invade many cell types


  • Cat is definitive host for sexual stage of reproduction



    • Trophozoites reproduce in intestinal epithelium


    • Oocysts are generated that are eliminated in feces


  • Humans and animals are intermediate hosts



    • Ingest oocysts from contaminated soil


    • Humans can ingest oocysts from undercooked meat


  • In humans and animals, oocysts are digested by digestive enzymes



    • Trophozoites are released into intestine



      • Organisms are carried by macrophages


      • Spread via lymphatics and blood vessels to internal organs


    • Within macrophages, trophozoites can multiply and become crescent-shaped tachyzoites


  • In immunocompetent patients, tachyzoites usually become segregated into cysts synthesized by host



    • Within cysts, organisms are slow-growing bradyzoites


    • Infection typically resolves


  • In immunodeficient patients, tachyzoites widely disseminate, causing acute infection


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Toxoplasmosis is common parasitic disease worldwide



      • More prevalent in warm and humid climates


    • In USA, toxoplasmosis is most common parasitic infection



      • 50% of USA citizens have serum antibodies to T. gondii: Evidence of chronic infection


    • T. gondii can be spread transplacentally from mother to fetus



      • 1 in every 1,000 live births in USA


      • ˜ 3,000 births are affected annually


      • Potential damage to fetus is greatest with infection in 1st trimester


    • Rarely, T. gondii infection can be transmitted via transplanted organ


    • Active infection may result from reactivation of earlier infection



      • Common in patients with cancers and diabetes mellitus


  • Age



    • Children and young adults most often affected


  • Gender



    • No sex preference


Site



  • Lymph nodes are commonly affected



    • Posterior cervical lymph nodes are characteristic site



      • Often unilateral


    • Any group of lymph nodes can be involved



      • Other cervical, supraclavicular, occipital, parotid, intramammary regions


    • Generalized lymphadenopathy or hepatosplenomegaly can occur but is unusual



Presentation



  • Asymptomatic infection is common in immunocompetent individuals


  • Mild illness also can occur manifested by malaise, fever, myalgia


  • Physical examination of lymph nodes



    • Tender or nontender


    • Firm but not rock hard


    • 0.5-3.0 cm


Laboratory Tests

Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Toxoplasma Lymphadenitis
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