Chilblain lupus is a rare cutaneous form of systemic lupus erythematosus (SLE; 152700) characterized by tender, bluish-red swellings and nodules on the hands, feet, ears, and nose, with histologic changes of lupus. The phenotype is induced by cold, such that patients frequently report a worsening of lesions in the winter months (summary by Ravenscroft et al., 2011). For a general description and a discussion of genetic heterogeneity of chilblain lupus, see CHBL1 (610448).