In early June, a 49-year-old woman with a medical history of chronic obstructive pulmonary disease, anxiety and depression presented to an emergency department in Manitoba, Canada, with a 1-day history of sore throat, subjective fevers, chills and fatigue. On examination, the patient had obvious exudate over the right tonsil and swollen anterior cervical lymph nodes, which was consistent with a diagnosis of pharyngitis. A throat swab for bacterial culture was not obtained, and she was prescribed amoxicillin-clavulanate to treat for presumed group A Streptococcus.
Two weeks later, the patient returned to the emergency department with an increase in swelling to the right side of her neck. She had enlarged, tender lymph nodes in the right upper internal jugular deep cervical chain. A computed tomography (CT) scan of the neck showed right-sided necrotic lymphadenopathy. The otolaryngology performed fine needle aspiration of a lymph node for pathology and mycobacterial culture. The patient received another prescription for amoxicillin-clavulanate and was discharged with a plan to follow up with otolaryngology as an outpatient.
In early July, the patient presented for a third time with increased swelling to the right side of her neck, and the infectious diseases service was consulted. Her sore throat, fever and chills had all improved, and she did not have dyspnea, odynophagia or discomfort in her teeth. A review of systems was otherwise negative. She was afebrile and hemodynamically stable. On examination, she had only tender right cervical adenopathy, with an otherwise normal systemic examination. On further history, the patient indicated that she lived in Winnipeg, Manitoba, with her daughter and 3 grandchildren. She smoked cigarettes and reported consuming 1-2 alcoholic beverages a month. She had no history of recreational drug use. She was originally from Ontario but had not left Manitoba for many years and had not recently travelled. She gave no history of exposure to tuberculosis or tick bites.
The patient had 3 outdoor cats and 1 dog at her place of residence. About 2 weeks before her initial presentation, one of the cats was diagnosed with a skin infection, which subsequently improved with antibiotics. The patient did not recall any recent animal bites or scratches, however, and she had no contact with wild animals nor had she consumed any meat or organs of wild animals.
On laboratory testing, the patient had an elevated white blood cell count of 13.4 (normal 4.5-11) * [10.sup.9]/L and a C-reactive protein level of 28 (normal < 5) mg/L. A repeat CT scan of the patient's neck showed a substantial increase in the size of the right-sided necrotic cervical lymph nodes (Figure 1). The patient was admitted to hospital by the otolaryngology service and underwent a bedside incision and drainage procedure, during which pus was aspirated. We thought the most likely diagnosis was either bacterial lymphadenitis with failure to respond to medical treatment owing to a need for abscess drainage or cat-scratch disease. However, the differential diagnosis of cervical lymphadenopathy is broad and includes infectious (e.g., Epstein-Barr virus (EBV), cytomegalovirus (CMV), HIV,...