Sight-Threatening Unilateral Posterior Scleritis With Positive Atypical p-ANCA As Early Manifestation of Lupus Spectrum Disease.

Antinuclear cytoplasmic antibody (ANCA)-related scleritis is a potentially sight-threatening inflammatory condition that may occur as a primary vasculitis disorder or as a secondary vasculitis in a variety of inflammatory conditions. While ANCA has been classically associated with primary vasculitis diseases such as granulomatosis with polyangiitis (GPA), microscopic polyarteritis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA), it is interesting that in cases of lupus spectrum disease (LSD), both ANCA and atypical p-ANCA have been observed as secondary autoantibodies. Scleritis is a rare ocular manifestation of lupus disease with an incidence of around 1%. This paper describes a case of sight-threatening posterior scleritis with positive atypical p-ANCA as an early manifestation of LSD. LSD is an acknowledged condition but frequently presents a diagnostic challenge or delay due to its ambiguous symptoms which may not fully align with the classification criteria of established systemic lupus erythematosus (SLE). Nonetheless, this condition should not be underestimated due to its potential impact on major organ involvement and its tendency to progress to established SLE. The diagnosis of LSD heavily relies on clinician suspicion, considering factors such as symptoms present in at least one organ system, positivity of antinuclear antibody (ANA), and clinical suspicion of future SLE development. Early identification allows for early treatment which would benefit high-risk patients. A middle-aged Chinese lady presented with bilaterally asymmetrical eye redness and swelling, which was worse on the right side. Clinical examination revealed right eye proptosis, conjunctival injection, chemosis, scleral redness and binocular diplopia in all gazes. Right eye fundoscopic examination displayed extensive choroidal folds with a positive T-sign on the B-scan. Apart from ocular symptoms, there was no significant medical history related to autoimmune or connective tissue disorders. Her p-ANCA and c-ANCA results were negative, however atypical p-ANCA titer was positive with a high antinuclear antibody (ANA) titer of 1:1280 with a homogenous pattern. Additionally, she has a family history of systemic lupus erythematosus in her daughter. A diagnosis of right eye posterior scleritis secondary to underlying LSD was made. The scleritis was successfully treated with a combination of corticosteroid and systemic immunosuppressants and the patient was initiated on oral hydroxychloroquine to manage underlying LSD. We aim to highlight to clinicians the diagnostic challenges associated with scleritis in LSD and emphasize the importance of prompt and timely multidisciplinary management in minimizing patient mortality and morbidity, as reflected in this case. This case of a positive atypical p-ANCA scleritis in LSD serves as an excellent example of effective management.