Autoimmune Disorders Characterized by Petechial Rash

Clinical Presentation and Diagnosis

• Adult-Onset Still's Disease (AOSD) can present with a vasculitic purpuric rash in some cases, with reported association with mixed cryoglobulinemia, characterized by perivascular inflammation of the superficial dermis with invasion of lymphocytes and histiocytes 1
• Petechial rashes in autoimmune conditions must be distinguished from infectious causes like Rocky Mountain Spotted Fever (RMSF), where the rash begins as small blanching pink macules that evolve to maculopapules and may progress to petechiae by day 5-6 2

Differential Diagnosis

• Viral causes like enteroviruses can produce petechial rashes that may mimic bacterial causes but typically progress more slowly, according to the American Academy of Pediatrics 3 is not used, instead:
• The Centers for Disease Control and Prevention recommends considering infectious causes like RMSF in the differential diagnosis of petechial rash 2