Angioedema as a Presenting Feature of Systemic Lupus Erythematosus With Myositis and Vasculitis—Successfully Treated With Mycophenolate and Prednisolone

Introduction Angioedema is a rare manifestation of systemic lupus erythematosus (SLE). Myositis and vasculitis are uncommon manifestations of SLE. The former being a harbinger and feature of the latter has not been reported. Method A case report of a 50-year-old white female. She was under the care of another specialist for seronegative rheumatoid arthritis over 2 years, managed with methotrexate 25 mg weekly. She was referred to the outpatient clinic with episodic airway-threatening angioedema, responding to prednisolone and antihistamines. While awaiting her first appointment, she was hospitalised with episodic monocular visual loss, diplopia, polyarthritis, myalgia, intermittent rashes, and further angioedema. Results Her antinuclear antibody (ANA) was 1:2,560 with a homogeneous immunofluorescence pattern—12 months ago, she had a 1:80 speckled ANA. Creatine kinase was elevated at 294, and C-reactive protein was elevated at 34; she had a normocytic anaemia, leukopenia, and neutropenia. A fluorodeoxyglucose positron emission tomogram (FDG-PET) scan showed widespread multifocal intramuscular avidity, leading to a muscle biopsy. Her original rheumatological diagnosis was questioned; on further assessment, she reported Raynaud’s phenomenon, alopecia, oral ulceration, and intermittent erythematous rashes. Her diagnosis was revised to SLE with probable myositis and possible vasculitis to explain her visual disturbance. Her Systemic Lupus International Collaborating Clinics (SLICC) score was 5. Prednisolone was commenced at 20 mg, along with hydroxychloroquine and mycophenolate sodium, titrated to 720 mg twice daily. Her symptoms, cytopenias, inflammatory markers, and CK normalised and have remained stable with a prednisolone taper to 12.5 mg. Conclusion The angioedema seen in this case responded to antihistamines, prednisolone, and immunosuppression. Its pathomechanism is unknown; however, it is likely a reactive phenomenon to her autoimmune disease and is likely histaminergic (other reported cases were bradykinin mediated). Physicians should screen for features of connective tissue diseases when evaluating patients presenting with angioedema.