Lymph nodes & spleen, nonlymphoma
Lymph nodes-infectious / parasitic disorders
Toxoplasmosis
Authors: Nat Pernick, M.D., William D. DePond, M.D.
Topic Completed: 1 June 2006
Minor changes: 7 April 2021
Copyright: 2003-2021, PathologyOutlines.com, Inc.
PubMed Search: Toxoplasmosis[TI] lymph nodes
Table of Contents
Definition / general | Pathophysiology | Diagrams / tables | Diagnosis | Case reports | Treatment | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Electron microscopy images | Differential diagnosisCite this page: Pernick N, DePond WD. Toxoplasmosis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/lymphnodestoxoplasma.html. Accessed April 16th, 2021.
Definition / general
- Common obligate intracellular parasite (Toxoplasma gondii) that is either asymptomatic, causes lymphadenitis or produces an acute infection during pregnancy that may damage fetus (US Department of Agriculture: Toxoplasmosis [Accessed 2 July 2018], eMedicine: Pediatric Toxoplasmosis [Accessed 2 July 2018])
- Also called Piringer-Kuchinka lymphadenitis
- Transmitted from cat feces (kitty litter) or undercooked meat
- Commonly involves posterior cervical nodes of young women but should be considered in differential diagnosis of tonsillitis, adenoid hyperplasia and chronic neck lymphadenopathy (Kulak Burun Bogaz Ihtis Derg 2004;13:132)
Pathophysiology
- Tachyzoites are the rapidly dividing form of T. gondii and the predominant form in acute and reactivated infections (Pritt: Creepy Dreadful Wonderful Parasites Blog - Answer to Case 519 [Accessed 14 February 2019])
- Numerous extracellular forms is evidence of an active infection
- Tissue cysts containing bradyzoites, the slowly replicating forms, are seen during latent infection
Diagrams / tables
Images hosted on other servers:
Life cycle
Diagnosis
- Based on morphology and serology (IgM antibody), as PCR and immunostains are usually negative in lymph nodes
- High IgG avidity only in patients who developed lymphadenopathy at least 4 months earlier (J Clin Microbiol 2004;42:4627)
Case reports
- 12 year old girl with infection of Toxoplasma gondii causing granulomatous common variable immunodeficiency (Clin Exp Immunol 2004;137:578)
- 24 year old sailor with diagnosis by direct immunofluorescence (J Clin Pathol 1977;30:847)
- 43 year old man with cervical toxoplasmosis due to family rabbit (Am J Clin Pathol 1990;94:107)
- Squash preparation of a brain biopsy (Pritt: Creepy Dreadful Wonderful Parasites Blog - Case of the Week 519 [Accessed 14 February 2019])
Treatment
- Pyrimethamine and either sulfadiazine or clindamycin
Microscopic (histologic) description
- Well preserved nodal architecture (J Clin Pathol 1961;14:565)
- Marked follicular hyperplasia with frequent mitotic figures and phagocytosis of nuclear debris, small noncaseating epithelioid granulomas with indistinct margins (presence within germinal centers is fairly specific for toxoplasmosis), distention of sinuses by monocytoid B cell with immunoblasts and plasma cells in medulla
- Occasionally granulomas exhibit necrosis or have frequent Langhans giant cells
- Recommended diagnostic criteria are either:
- (1) Florid reactive follicular hyperplasia, clusters of epithelioid histiocytes and focal sinusoidal distention by monocytoid B cells (Pathol Int 2001;51:619)
- (2) Microgranulomas, absence of giant cells, lower than grade 2 macrogranuloma and follicular hyperplasia (J Clin Pathol 2005;58:1143)
Microscopic (histologic) images
Contributed by Bobbi Pritt, M.D. and AFIP images
Tachyzoites of Toxoplasma gondii
Toxoplasmic lymphadenitis
Cytology description
- Epithelioid microgranulomas (small clusters of epithelioid histiocytes with abundant, pale staining and homogenous cytoplasm and eccentric, oval nuclei but no necrosis, giant cells or neutrophils) are characteristic (Acta Cytol 2005;49:139)
- Reactive hyperplasia and tachyzoites within lymphocytes (Acta Med Croatica 2005;59:153)
- Pap stain may demonstrate parasite on FNA (Acta Cytol 2003;47:299)
Electron microscopy images
Contributed by Bobbi Pritt, M.D.
Tachyzoites of Toxoplasma gondii
Differential diagnosis
