Immunodeficiency and autoimmunity coming together: a nearly missed diagnosis.

The coexistence of human immunodeficiency virus (HIV) and systemic lupus erythematosus (SLE) appears to be unusual and the prevalence of patients who carry the dual diagnosis is currently unknown. We hereby present a case of a C4 deficient HIV-1 positive Caucasian female under highly active antiretroviral therapy for the past eight years, admitted to hospital with an aggressive and potentially fatal clinical presentation of SLE. There was a favorable outcome despite a significant diagnostic delay. Despite its rarity, the case highlights that this association is remarkable and may be overlooked by clinicians familiar with either condition.