A 47-year-old woman presented with a painful, compressible, and mobile lump in the left axilla for three days without discharge or erythema. Prior to lump presentation, the patient had intermittent elbow and arm pain, lasting approximately 45 minutes. She denied fevers, chills, and night sweats. Her family history was significant for a father with liver cancer and maternal grandmother with bone cancer. She worked as a veterinarian and was a former smoker of five pack-years. On physical examination, there was a compressible, mobile, tender lump measuring 30 x 20 mm in the left axilla. Mammogram revealed normal right breast and left axillary lymphadenopathy (Figures , ). The ultrasound showed two adjacent enlarged axillary lymph nodes measuring 31 mm and 27 mm in diameter, respectively (Figure ).\nThe results from the mammogram and ultrasound supported the physical exam findings, prompting further CSD assessment with ultrasound-guided core biopsy. The biopsies showed necrotizing lymphadenitis that partially effaced the lymph node architecture. In the necrotic area, there were microabcesses with neutrophils and surrounding histiocytes, some of which were palisading (Figure ). Giant cells were scattered throughout. Staining for cluster of differentiation 20 and cluster of differentiation 3 showed some residual follicles and interfollicular T cells. Other stains including acid-fast bacilli, methenamine silver stain, toxoplasmosis, and periodic acid-Schiff were all negative. Cat scratch stain was positive. To confirm the diagnosis, serology for B. henselae was subsequently ordered with the results of abnormal B. henselae IgG titer of 1:1024, and abnormal B. henselae antibody IgM titer of 1:32.
A 58-year-old woman presented with breast and rib pain. She reported left axillary lymphadenopathy, abdominal fullness, and malaise. She denied fever and breast drainage. Her past medical history was significant for hepatitis C. Socially, she had two cats and was bitten by a cat a month prior. Review of systems was positive for fatigue and negative for appetite change, chills, diaphoresis, and fevers. Lung cancer screening CT, which was completed a day prior to this visit, showed an ill-defined mass measuring up to 3.5 cm in the left axilla. There was mild adjacent soft tissue stranding. These findings indicated an infectious, inflammatory, or malignant process. She was promptly treated with doxycycline for CSD, but also recommended to obtain a diagnostic mammogram and an ultrasound of the left axilla. The imaging showed an enlarged lymph node with an adjacent abscess, which altogether measured 30 x 17 mm in the left axilla (Figure ).\nTherefore, a lymph node biopsy and drainage of the abscess with culture were ordered. The lymph node biopsy revealed necrotizing granulomatous inflammation with the following differential diagnosis: CSD, tuberculosis, and other infectious entities. The abscess culture was negative for aerobic/anaerobic organisms and showed few polymorphonuclear leukocytes. Given her history of a cat scratch, symptoms, and pathology results, an infectious etiology was most likely. To confirm the diagnosis and rule out other causes, serology for B. henselae was ordered which showed high B. henselae IgG titer of >1:1024 and IgM titer of 1:128.