Hypocomplementemic urticarial vasculitis and multiple Sclerosis: A rare association or an atypical presentation?

Background: Multiple Sclerosis (MS) has been associated with several immune-mediated diseases but the mechanisms that explain such associations, as well as their implications in clinical practice and treatment are rarely discussed.

Case presentation: We report the case of a patient with a history of MS since she was 27 years old, followed by a diagnosis of Hypocomplementemic Urticarial Vasculitis (HUV) seven years later. Several disease-modifying treatments for MS and HUV were used but with limited benefit in both diseases and significant MS progression. Activity of both diseases was later stabilized with Rituximab. We discuss the hypotheses of a central nervous system involvement in urticarial vasculitis or an association between MS and HUV, and examine the challenges in their management.

Conclusions: In the presence of concurrent immune-mediated diseases, the diagnosis of MS can be challenging. This clinical presentation posed significant difficulties in disease management, influencing therapeutic options and their effectiveness/adverse effects profile. The best approach in MS patients with concurrent autoimmune diseases remains to be established and more reports are needed to help clarify this subject.