C. Neuromyelitis optica spectrum disorder associated with Sjögren syndrome
The initial clinical suspicion for GCA was high given the patient’s classic presentation—a woman older than 65 years with sequential bilateral vision loss accompanied by scalp tenderness, jaw claudication, weight loss, and musculoskeletal pain suggestive of polymyalgia rheumatica. Expedited evaluation and treatment are critical in suspected GCA. Initial laboratory workup should include ESR, CRP, and platelet count tests. Chan et al1 found that these 3 tests have similar sensitivity (range, 65%-71%) and specificity (range, 57%-62%) for GCA. The gold standard of GCA diagnosis is TAB, but the sensitivity is only 77%.2 Empirical treatment should not be delayed for TAB because the positivity rate is similar after up to 4 weeks of systemic corticosteroid therapy.3 In this clinically suspicious patient with ESR elevation but normal CRP level and platelet count and negative TAB results, GCA remained a plausible diagnosis to justify continued corticosteroid therapy.