Regional lymphadenopathy with low-grade fever after kitten contact, caused by Bartonella henselae; usually self-limited but can cause systemic disease in immunocompromised hosts.
Also known as: CSD, Bartonella henselae, Bartonellosis, bacillary angiomatosis, Parinaud oculoglandular syndrome
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Risk factors
- Exposure to kittens, particularly flea-infested
- Recent cat scratch or bite
- Children and adolescents
- HIV/AIDS or other immunocompromise (bacillary angiomatosis, peliosis hepatis)
- Pre-existing valvular disease (culture-negative endocarditis)
Pathophysiology
Bartonella henselae is transmitted from cat to cat by the cat flea (Ctenocephalides felis). Human inoculation through a scratch or bite leads to local replication and lymphatic spread. In immunocompetent hosts, granulomatous inflammation with stellate microabscesses develops. In immunocompromised hosts, vascular proliferation predominates (bacillary angiomatosis).
Clinical presentation
Symptoms
- Papule or pustule at inoculation site within 3-10 days, often unnoticed
- Tender regional lymphadenopathy 1-3 weeks later — axillary, cervical, or epitrochlear most common
- Low-grade fever, fatigue, headache, malaise
- Parinaud oculoglandular syndrome: granulomatous conjunctivitis with preauricular lymphadenopathy
Signs / physical exam
- Single or matted tender lymph nodes, 1-5 cm
- Overlying skin sometimes erythematous; occasional spontaneous suppuration
- Hepatosplenic microabscesses on imaging in atypical CSD
- In immunocompromised: violaceous vascular papules of bacillary angiomatosis
Classic findings
Adolescent with a kitten and a 3-cm tender axillary node a week after a scratch on the ipsilateral hand.
Differential diagnosis
- Mycobacterial lymphadenitis (nontuberculous or M. tuberculosis) — Indurated, often violaceous nodes in children; AFB stain and culture, IGRA
- Tularemia (ulceroglandular) — Rabbit or tick exposure; painful ulcer with regional lymphadenopathy; serology
- Lymphoma — Painless, progressive, multistation lymphadenopathy with B symptoms; excisional biopsy
- Reactive lymphadenitis (viral, dental) — Bilateral, tender, resolves with treatment of source
- Sporotrichosis — Gardener with rose-thorn or soil exposure; lymphocutaneous nodular pattern
- Plague (bubonic) — Flea bite in endemic Southwest US; rapidly enlarging painful bubo with sepsis
Diagnostic workup
Diagnostic criteria
Cat exposure plus regional lymphadenopathy plus positive Bartonella serology (or PCR or histopathology) supports the diagnosis.
Labs
- Bartonella henselae IgG and IgM serology — preferred initial test (IFA or EIA)
- Bartonella PCR on lymph node aspirate or tissue if serology equivocal
- Histopathology: stellate granulomas with necrosis; Warthin-Starry silver stain shows organisms
- CBC and inflammatory markers
- Blood cultures if endocarditis suspected (special media required; often culture-negative)
Imaging
- Ultrasound of involved nodes for size and suppuration
- CT/MRI abdomen for hepatosplenic disease in prolonged fever of unknown origin
- Echocardiogram if endocarditis suspected
Treatment
First-line
- Most cases in immunocompetent hosts are self-limited over 2-4 months and require no antibiotics
- Symptomatic care: NSAIDs, warm compresses
- Treat severe disease, large suppurative nodes, or immunocompromise: azithromycin (5-day course is standard) — only RCT-supported regimen for CSD
- Doxycycline (cat scratch, Q fever, brucellosis, RMSF) is used for systemic Bartonellosis including retinitis and neuroretinitis
- Rifampin added to doxycycline for severe disease and endocarditis (often combined with gentamicin)
Bacillary angiomatosis / peliosis hepatis (HIV)
- Erythromycin or doxycycline for at least 3 months
- Treat HIV and reconstitute immunity
Endocarditis
- Doxycycline + gentamicin for 2 weeks, followed by doxycycline + rifampin for at least 6 weeks
- Valve surgery often required
Neuroretinitis / encephalopathy
- Doxycycline + rifampin for 4-6 weeks
Second-line / adjunct
- Needle aspiration (not incision and drainage) for tense suppurative nodes — relieves pressure and pain
- Avoid I&D, which can produce chronic sinus tracts
Complications
- Suppurative lymphadenitis
- Parinaud oculoglandular syndrome
- Neuroretinitis with macular star
- Encephalopathy and seizures
- Hepatosplenic microabscesses
- Bacillary angiomatosis (HIV/AIDS)
- Culture-negative endocarditis
PANCE pearls
- Aspirate tense suppurative nodes — do NOT incise and drain (risk of sinus tract).
- Azithromycin is the only antibiotic with RCT evidence shortening lymphadenopathy in CSD.
- Bacillary angiomatosis in HIV is a great mimic of Kaposi sarcoma — biopsy and Warthin-Starry stain distinguish.
- Bartonella is a leading cause of culture-negative endocarditis (along with Coxiella, HACEK, Brucella).
- Neuroretinitis with macular star and unilateral vision loss in a young patient = think CSD.
References
- CDC — CDC Bartonella henselae infection (cat scratch disease) clinician guidance
- AAP Red Book — American Academy of Pediatrics Red Book — Bartonella henselae
- AHA 2015 — AHA Scientific Statement on Infective Endocarditis (Baddour et al., Circulation 2015)
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