Although clinical criteria exist for the classification of systemic vasculitides, certain cases defy precise classification. In this case series, Lee et al describe a series of 5 young women with slowly progressive, patchy, subtly indurated hyperpigmentation associated with fixed livedo racemosa affecting predominantly the lower limbs. The histologic findings revealed a dense mononuclear cell infiltrate that invaded the walls of arterioles in the dermosubcutaneous junction, associated with nuclear dust and a hyalinized fibrin ring encircling the entire periphery of the lumina of affected vessels. Four patients tested positive for antiphospholipid antibodies on serologic analysis. The authors term this newly described condition lymphocytic thrombophilic arteritis.