Cat Scratch Disease of the Breast/Axilla: Recognition of a Rare Disease and Approaches for Differential Diagnosis.

This article focuses on cat scratch disease (CSD) involving the breast and axilla, a rare presentation that can mimic breast carcinoma clinically and radiologically. CSD, caused by the bacterium Bartonella henselae, predominantly affects women with axillary lymphadenopathy and often an ipsilateral breast mass located mainly in the upper outer quadrant. Diagnosis is challenging due to nonspecific findings and limited tissue from biopsies; while gram stains are consistently negative, silver stains such as Warthin-Starry detect the organism in about half of cases, and polymerase chain reaction (PCR) testing shows the highest sensitivity. The article emphasizes the importance of considering CSD in the differential diagnosis of granulomatous mastitis and recommends combining clinical history, serologic testing, silver staining, and PCR to confirm diagnosis promptly, especially in patients with exposure to cats or other domestic animals.