A case of a 28-year-old woman with known C1-inhibitor deficiency (functional, Type II) with persistent bilateral non-pruritic, mildly photosensitive facial rash for 10 months following delivery of her second child is presented. Histology of the skin was suggestive of tumid lupus erythematosus (LE), but no other features of systemic LE (ANA, dsDNA negative) were evident. She had stopped danazol which was controlling the underlying disease, and once this was restarted and treatment for tumid lupus was started, she improved. More rigorous control preventing all C1-inhibitor deficiency-related attacks proved successful. The hypothesis that uncontrolled classical pathway complement activation that led to the lupus-like skin lesions is being presented as a clinical case, highlighting the complex interrelationships between immunodeficiency and autoimmunity in inborn errors in immunity.
Keywords: C1-inhibitor deficiency; complement deficiency; lupus; tumid lupus.