Vyas NS, et al. - Researchers conducted this case series to characterize the evolving histopathology of rickettsialpox, zoonotic disease caused by the bacterium Rickettsia akari, throughout its clinical course and also illuminate the histopathologic features in cases confirmed by immunostaining at the Centers for Disease Control and Prevention in Atlanta, GA. Cases of “rickettsialpox” with positive immunostaining for Spotted Fever Group Rickettsia species diagnosed between 2006-2018 were searched. They confirmed that predominantly lymphocytic (CD3+ T-cell) vasculitis occurs in cutaneous lesions of rickettsialpox and that pathogenesis is similar to septic vasculitis. Furthermore, it has been documented that hydropic (vacuolar) changes at the dermoepidermal junction and vasculitis are the most valid (albeit nonspecific) findings in these skin biopsies, as they were occur in each lesional stage of rickettsialpox (ie eschars, papules and vesiculopapules).