Microscopical examination of biopsy specimens from cat-scratch skin test sites, performed in patients with catscratch disease (CSD), sarcoidosis, tuberculosis, and other granulomatous diseases, showed noncaseating granulomatous dermal inflammation in 11 of 12 patients with CSD and in some patients with sarcoidosis or tuberculosis. Biopsy of cat-scratch skin test sites may be a useful ancillary procedure in diagnosing CSD if other granulomatous diseases are excluded.
Czarnetzki BM, Pomeranz JR, Khandekar PK, Wolinsky E, Belcher RW. Cat-Scratch Disease Skin TestStudies of Specificity and Histopathologic Features. Arch Dermatol. 1975;111(6):736-739. doi:10.1001/archderm.1975.01630180064007