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Tularemia Lymphadenitis

View larger version (177K): [in this window] [in a new window]   Figure 1. Reactive lymph node containing a serpigenous necrotizing palisaded granuloma. H&E stain. 40x Magnigication.

View larger version (185K): [in this window] [in a new window]   Figure 2. Area of coagulative necrosis lined by a granulomatous reaction comprised of epithelioid histiocytes. H&E stain. 100x Magnification.

View larger version (179K): [in this window] [in a new window]   Figure 3. Neutrophil-rich areas within the coagulative necrosis form microabscesses. H&E stain. 200x Magnification.

	Clinical Summary

TOP Clinical Summary Diagnosis Discussion Differential Diagnosis

Sex
Male

Age
41

Ethnicity
Caucasian

	Diagnosis

TOP Clinical Summary Diagnosis Discussion Differential Diagnosis

 
Ulceroglandular Tularemia

	Discussion

TOP Clinical Summary Diagnosis Discussion Differential Diagnosis

 
Tularemia is a zoonosis caused by the facultative, Gram negative, coccobacillus Francisella tularensis. F.tularensis is an intracellular bacteria capable of eliciting a granulomatous tissue response. Humans are accidental hosts following contact with infected animals (or animal products), vectors (e.g., ticks, biting flies, and mosquitoes) or from drinking contaminated water. Although widespread, tularemia occurs primarily in the Northern hemisphere. There are six distinct clinical syndromes that have been recognized, including (1) ulceroglandular, (2) glandular, (3) oculoglandular, (4) typhoidal (septic illness), (5) pneumonic and (6) oropharyngeal tularemia. Lymphadenopathy is an essential feature in the first three clinical types, and predominates in the axillary region when mammalian vectors are involved and in the cervical or inguinal regions with arthropod vectors. Cervical and occipital adenopathy is more common in children whereas enlarged inguinal nodes are most common in adults. Ulceroglandular disease accounts for 60-80% of cases. Affected patients present with fever and a single erythematous cutaneous papule that subsequently ulcerates. F.tularensis is highly virulent, as only 10-50 bacteria are necessary to produce a clinical illness. The incubation period is 2-10 days. Bacteria spread from the site of entry to regional lymph nodes, resulting in tender lymphadenopathy with possible spontaneous drainage of suppurative lymph nodes. Lymphadenopathy without an identifiable skin lesion (glandular tularemia) occurs in 3-15% of patients.
 
Routine laboratory tests in tularemia are nonspecific. Routine culture of blood, skin lesions, lymph nodes or other clinical specimens are frequently negative because these organisms are fastidious and grow slowly. Most strains require cysteine/cystine for their growth. Histopathologic findings of infected lymph nodes vary with the duration of the disease. In very early tularemia there may be reactive follicular hyperplasia, non-necrotizing granulomas and/or diffuse histiocytosis. Abscess formation becomes prominent during the second week and necrosis during the fourth week. However, necrosis can be observed as early as five days after the onset of symptoms. Suppuration of involved lymph nodes may occur even after specific antibiotic therapy. The granulomatous reaction seen lining areas of necrosis is comprised of foamy and/or epithelioid macrophages and infrequently giant cells. In most cases, the inflammatory process may extend beyond the capsule of the lymph node. Silver stains (Steiner, Dieterle and Warthin-Starry) may demonstrate organisms, which are usually localized within macrophages. Serologic studies, however, are the most common way to confirm the diagnosis of tularemia. A diagnostic increase in antibody titer generally occurs 2-4 weeks after the onset of disease. Antibody titers may remain elevated for years after an infection. DFA and PCR on lymph node tissue or aspirates can also be performed. PCR is helpful in that it may be positive even after antibiotic therapy is initiated. Streptomycin is the therapeutic drug of choice. Although the overall mortality today is low (only 2-4%), tularemia should always be considered in the differential diagnosis of a necrotizing granulomatous lymphadenitis. Tularemia lymphadenitis is easy to diagnose with ancillary serologic and molecular techniques and is amenable to treatment.

	Differential Diagnosis

TOP Clinical Summary Diagnosis Discussion Differential Diagnosis

 
The microscopic picture of tularemia lymphadenitis is not pathognomonic of this disease. The differential diagnosis for necrotizing granulomas in a lymph node includes a variety of infectious causes, such as bacteria (cat-scratch disease, lymphogranuloma venereum, and rarely syphilis), atypical mycobacterial and fungal infections. Non-infectious causes such as systemic lupus lymphadenitis and Kikuchi-Fujimoto disease should also be included. Both of these entities lack neutrophils and contain conspicuous C-shaped histiocytes. Lupus also has plasmacytosis and Hematoxylin bodies (DNA material). Clinically, necrotizing granulomatous lymphadenitis caused by Bartonella henselae (cat-scratch disease) presents with a similar papuloulcerative skin lesion (at the site of a cat scratch) as tularemia accompanied by matted regional lymphadenopathy. In cat-scratch disease, lymph node microabscesses surrounded by a peripheral rim of epithelioid macrophages also result in stellate necrotizing granulomas. Silver stains may show focal clusters of Bartonella bacilli centered in areas of necrosis. The sexually transmitted disease lymphogranuloma venereum (LGV), caused by Chlamydia organisms, presents with inguinal lymphadenopathy and a painless genital lesion that usually goes unnoticed. Lymph nodes in LGV also have stellate necrotizing granulomas. Necrotizing lymphadenitis in syphilis is rare, and usually accompanied by a perivascular plasma cell infiltrate. In tuberculous lymphadenitis there is caseous necrosis (i.e. coagulative necrosis without nuclear remnants) within granulomas, lack of neutrophils and occasional intracellular and/or extracellular acid-fast bacilli. However, granulomas in tularemia show less distinct borders and fewer giant cells than those in tuberculosis. Atypical mycobacterial lymphadenitis, caused by non-tuberculous mycobacteria, may have polymorphonuclear leukocytes in areas of necrosis. Fungal lymphadenitides (e.g. cryptococcosis and histoplasmosis) with necrotizing granulomas usually require Grocott methenamine silver staining to reveal yeasts. Necrotizing lymphadenitis seen in autoimmune disease and Kikuchi-Fujimoto disease lack a granulomatous reaction. Finally, while Hodgkin lymphoma may contain neutrophils and a rare neutrophil-rich variant of CD30-positive anaplastic large cell lymphoma can contain many neutrophils, in general, tissue neutrophilia is rare in lymphoma.

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This Article Figures Only Services Similar articles in this journal Alert me to new content in the Image Bank Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Pantanowitz, L. Articles by Kadin, M. Search for Related Content PubMed Articles by Pantanowitz, L. Articles by Kadin, M. Related Collections Nonlymphoid Lesions of Lymph Nodes and Spleen Related ASH-SAP Chapter Related Image Bank Image Sets Social Bookmarking                   What's this?