Table of Contents
Definition / general | Historical criteria | Case reports | Gram stain | Diagnosis | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Electron microscopy description | Differential diagnosis | Additional referencesCite this page: DePond WD. Cat scratch disease. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/lymphnodescatscratch.html. Accessed January 24th, 2021.
Definition / general
- Caused by Bartonella (formerly Rochalimaea) henselae (Am J Clin Pathol 1994;101:607), harbored by kittens and young cats; transmitted between cats by cat flea (but not from cats to humans)
- Adults or children (85% under age 18) infected by cat claws contaminated with infected flea feces; 24K cases / year in US (most common cause of chronic benign lymphadenopathy)
- Cutaneous red papule 7 - 12 days after contact that may become crusted or pustular, with enlargement of cervical or axillary nodes
- May have necrotizing granulomas in liver, spleen or bone
- Usually resolves spontaneously; erythromycin or other macrolides may be given
- Rare complications are granulomatous conjunctivitis, thrombocytopenic purpura, CNS disease (Eur J Intern Med 2005;16:610)
Historical criteria
- Exposure to cat and presence of scratch or dermal / eye lesion
- Positive cat scratch disease antigen skin test
- Regional lymphadenopathy with negative culture for other possible causes
- Characteristic changes in nodal biopsy
Case reports
- 16 year old boy with tender cervical adenopathy (Arch Pathol Lab Med 2005;129:1065)
- 32 year old HIV infected woman with B. quintana and M. tuberculosis coinfection (J Infect 2003;46:244)
Gram stain
- Pleomorphic, curved, gram negative coccobacillus
- Catalase negative, oxidase negative
- Difficult to culture, but prolonged incubation is helpful (J Clin Microbiol 2002;40:3620)
Diagnosis
- PCR (Am J Clin Pathol 2001;115:900, Arch Pathol Lab Med 2003;127:706, J Clin Microbiol 2005;43:3800)
- Serology, immunofluorescence (Clin Diagn Lab Immunol 2003;10:686)
- Possibly culture
Gross images
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Lesion on finger
Microscopic (histologic) description
- Early - histiocytes and follicular hyperplasia
- Intermediate - capsulitis and subcapsular granulomas
- Late - abscesses
- In general, necrosis is often stellate with neutrophils, surrounded by palisading histiocytes
- Paracortical vascular proliferation
- Sinuses are often packed with monocytoid B cells, but no epithelioid cells are present
- Small rods may be present with silver stain around small blood vessels and lymphatics
- Skin shows dermal necrosis surrounded by histiocytes
- Also multinucleated giant cells, lymphocytes and eosinophils
Microscopic (histologic) images
Contributed by Mark R. Wick, M.D.
Lymph node biopsy
Steiner stain
Positive stains
Electron microscopy description
- Extracellular bacteria form small groups within bundles of collagen fibrils
- Bacteria are gram negative pleomorphic rods, with thick and homogeneous cell walls (Am J Clin Pathol 1987;87:739)
Differential diagnosis
- Brucellosis
- Fungi
- Kikuchi syndrome: no neutrophils
- Lymphogranuloma venereum: similar necrosis pattern but affects inguinal nodes
- Mycobacterium avium intracellulare: no zonation, bacteria are acid fast positive
- Toxoplasmosis: also has monocytoid B cells
- Tularemia: usually constitutional symptoms, no well defined rim of histiocytes
- Yersinia
Additional references
