Cat scratch disease


Step 1: View clinicals

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.

Step 2: Order all 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 .

Cat scratch disease skin test

The cat scratch disease skin test is negative.

Step 3: Select appropriate management

Warm compresses

Score: ★★☆