Urticarial Hypocomplementemic Vasculitis Syndrome and Systemic Lupus Erythematosus: a case report and review of the literature

Yasmina Ouerdani¹Tayssir Ben Achour^2,3Ahlem Ben Hmid^1,2,4Fatma Said^2,3Imen Ayadi^2,5Alia Zehani Kassar^2,6Maysam Jridi^2,3Imed Ben Ghorbel^2,3Ines Naceur^2,3Samar Samoud^1,4Yousr Galai¹Lilia Laadhar^2,5Slim Haouet^2,7Maryam Kallel Sellami^2,5Monia Smiti^2,3Imen Zamali^1,2,4*Mélika Ben Ahmed^1,2,4

• ¹Clinical Immunology Department, Pasteur Institut of Tunis, Tunis, Tunisia
• ²Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
• ³Department of Internal Medicine, Rabta University Hospital,, Tunis, Tunisia
• ⁴Laboratory of Transmission, Control and Immunobiology of Infection, Pasteur Institute of Tunis,, Tunis, Tunisia
• ⁵Immunology Laboratory, Rabta University Hospital,, Tunis, Tunisia
• ⁶Department of Pathology, Rabta University Hospital, Tunis, Tunisia
• ⁷Department of Pathology, Rabta University Hospital,, Tunis, Tunisia

Background: Hypocomplementemic urticarial vasculitis (HUV) syndrome is a rare form of smallvessel vasculitis characterized by a heterogeneous spectrum of clinical and biological findings. It is typically marked by chronic urticarial eruptions, hypocomplementemia and histopathological evidence of leukocytoclastic vasculitis (1). It may also involve multiple organ systems, with frequent articular, gastrointestinal, renal, and other systemic manifestations (1). The differential diagnosis with other systemic autoimmune diseases, particularly systemic lupus erythematosus (SLE), is often challenging due to their frequent association and the blurred boundaries between these entities (2,3).We report the case of a 34-year-old Tunisian man with an association of HUV and SLE. The diagnosis of SLE was established according to the 2019 European League Against Rheumatism (EULAR) criteria, based on the combination of inflammatory polyarthralgia, lymphopenia, a high titer of anti-nuclear antibodies, specific anti-Sm and anti-DNA antibodies, and consumption of C3 and C4 complement fractions. The diagnosis of HUV was made based on the presence of two major criteria: chronic urticaria and hypocomplementemia, along with four minor criteria: leukocytoclastic vasculitis, recurrent abdominal pain, episcleritis, and the presence of anti-C1q antibodies. Conclusion: HUV and SLE share key clinical, immunological, and pathophysiological features, suggesting that they may lie along the same spectrum of autoimmune diseases. Their association, as seen in our patient, has been described in the literature. This overlap may result in more severe disease and requires close clinical follow-up.