Toxoplasma Lymphadenitis

Toxoplasma Lymphadenitis

Carlos E. Bueso-Ramos, MD, PhD

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

H&E-stained section reveals a reactive germinal center with many centroblasts, tingible body macrophages, and epithelioid cells encroaching into the germinal center from the right image.



  • Glandular toxoplasmosis

  • Piringer-Kuchinka lymphadenopathy


Toxoplasma gondii Infection

  • T. gondii is a protozoan parasite of the phylum Apicomplexa that can invade many cell types

  • Cat is definitive host for sexual stage of reproduction

    • Trophozoites reproduce in intestinal epithelium, producing oocysts

    • Oocysts are eliminated in feces

    • Oocysts mature to infective stage in soil in 2-21 days

  • 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 within the lymphatic system 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



  • 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 population 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

      • Contamination of food &/or water by oocysts commonly causes human infection

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

      • Intrauterine death, microcephaly or hydrocephaly with intracranial calcifications may develop

      • Infections in the 2nd 1/2 of pregnancy are asymptomatic at birth

      • Fever, hepatosplenomegaly, and jaundice may appear

      • Chorioretinitis, psychomotor retardation, seizures appear months or years later

    • 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

    • Sexes equally affected


  • Lymph nodes are commonly affected (95%)

    • Posterior cervical lymph nodes are characteristic site

      • Often unilateral, firm, 0.5-3.0 cm, tender or nontender

    • Any group of lymph nodes can be involved

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

    • Generalized lymphadenopathy or hepatosplenomegaly can occur but is unusual


  • Asymptomatic infection is common in immunocompetent individuals

  • In immunosuppressed patients, CNS involvement is common

  • Mild malaise, fever, myalgia

  • Pneumonitis, myocarditis, retinitis, pancreatitis, polymyositis, orchitis

Laboratory Tests

  • Sabin-Feldman dye test

    • Highly sensitive and specific

    • T. gondii organisms do not stain with alkaline methylene blue if they have been exposed to serum anti-T. gondii antibodies

    • Positive result: Change from negative to positive or rapidly increasing IgG titers

  • Antibodies to T. gondii can be detected by enzyme immunoassays or indirect immunofluorescence

    • IgM or IgG antibodies against cell wall antigens

    • IgM antibodies present within few days after infection

      • Titers of 1:80 or higher indicate recent infection

      • IgM and IgA antibodies are 93% sensitive detecting congenital toxoplasmosis

    • IgG antibody titers of 1:1,000 occur 6-8 weeks after infection

    • Antibody to 11-kDa sporozoite protein detects infection with oocysts formed in cats

  • Latex agglutination test is available


  • In immunocompetent patients, infection is self-limiting

  • In immunodeficient patients, great risk of acute dissemination

    • Encephalitis, chorioretinitis, pneumonia, and cardiac involvement

    • Death as result of above conditions

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

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