A 7-year-old boy presents with a lump in his right axilla for 1 month. This has gradually increased in size over time, but is neither painful nor tender.
Around 1 week after the onset of symptoms, he was shown to a primary care physician, who suspected pyogenic lymphadenitis and prescribed a course of cephalexin, without relief.
His medical and surgical histories are unremarkable and all immunizations are up to date. There is no history of exposure to tuberculosis, and he has not come into contact with cats recently.
A complete blood count, C-reactive protein assay, ESR, and renal and liver profiles are all normal.
Select Relevant Investigations
Ultrasound neck + R/s axilla
There are multiple enlarged lymph nodes in the right posterior cervical chain and right supraclavicular region, as well as an enlarged, hypoechoic, lobular lymph node in the right axilla, measuring 4 x 4cm in size.
Diagnostic lymph node biopsy
Histopathological examination of the biopsy specimen of the right axillary lymph node shows lymphoid hyperplasia, multiple granulomas, and stellate microabscesses. The Ziehl-Neelsen, Warthin-Starry, silver-methenamine, and periodic acid-Schiff (PAS) stains are all negative.
Atypical infection screen
Positive for Bartonella, with a 1:512 titer.
Negative for Toxoplasma, Brucella, Tularemia, and HIV .