P3D383: Curious Cat Scratch – a Case Report of Bartonella Cervical Adenitis Requiring Surgical Intervention

Introduction: Cat Scratch Disease is caused by a fastidious gram-negative bacterium, Bartonella henselae that is typically transmitted to humans through the bite or scratch of cats, especially kittens and stray cats. Infection most commonly presents as subacute regional lymphadenitis located proximal to the site of inoculation, and a papule is often discovered at the site of initial scratch/bite. Most cases are self-limited and do not require antibiotics or surgical intervention.

Case Description: 13-year-old male developed right sided cervical lymphadenitis a week after playing with a stray cat. Initial evaluation by the ED included a CBC, CMP, LDH, Uric Acid, ESR, CRP, Rapid strep, RVP, QuantiFERON, and titers for EBV, CMV, and B. henselae. Initial labs notable for elevated inflammatory markers. Patient’s chest radiograph was unremarkable, and ultrasound displayed an enlarged right cervical chain node. He was discharged on clindamycin for suspected bacterial lymphadenitis. Next week, B. henselae IgM/G titers returned positive, and patient was started on a course of azithromycin. After completion, the mass was unchanged and was causing impairment in neck range of motion prompting referral to surgery. Exam revealed a 5x8 cm, tender, fluctuant mass on the right neck in the upper third of the posterior triangle, without erythema or drainage and no inoculation papule seen. CT of the neck, displayed an intramuscular abscess in the sternocleidomastoid muscle with mass effect on the internal jugular vein with multiple prominent regional lymph nodes. Given the failure the infection to improve with time, antibiotics, ongoing limited ROM, and to rule out malignancy, incision and drainage with drain placement was performed with a second course of azithromycin. Collected fluid was sent for Bartonella PCR (positive), Warthin-Starry staining (no organisms visualized), histology, cytology (no malignant cells), and aerobic/anaerobic cultures (sterile). At follow-up, he had significantly improved with no re-accumulation of the mass or fistula formation.

Discussion: The differential for bartonella adenitis includes tuberculous adenitis, non-tuberculous mycobacterial adenitis, EBV adenitis, toxoplasma, tularemia and malignancy. Initial evaluation will depend on the patient’s clinical status and overall course of adenitis. Bartonella henselae adenitis is typically self-limited and usually does not require intervention. Routine incision and drainage is not typically recommended due to high association of development of draining sinus tracts. However, as demonstrated in our patient, incision and drainage may be necessary when the abscess is causing patient discomfort or impacting activities of daily living.

Conclusion: Though Cat Scratch Disease is mostly a pediatric infection, it can also impact members of the fleet in forward deployed austere environments due to exposure to animal reservoirs. This case highlights the importance of maintaining a high index of suspicion for this pathogen as a cause of subacute cervical adenitis and the need for further exploration of optimal medical and surgical treatment options.