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We thank Brikman et al for their letter in response to our article1 describing a South Australian cohort of patients with muscle vasculitis in which we delineated the subgroups of patients with systemic vasculitis and isolated muscle vasculitis (IMV), the latter of which included those with localized muscle disease (IMV-LMD) and connective tissue disease–associated IMV. Nonischemic contributors to myalgia in muscle vasculitis may include sensitization of nerve fibers from the release of vasoactive substances around the prolifically inflamed vessels, metabolic accumulation of lactic acid due to reduced but not critically reduced blood supply, and oxidative stress from dynamic ischemic and reperfusion events. Brikman et al additionally raise concerns about muscle biopsy in the workup of suspected muscle vasculitis. In general, tissue evidence of vasculitis is helpful to confirm small-vessel vasculitis, especially in the absence of antineutrophil cytoplasmic antibodies (ANCA).3 In cases of IMV-LMD in which there are no extramuscular features of vasculitis and ANCAs are absent,1 biopsy is particularly important to identify vasculitis. Differentiating muscle vasculitis from idiopathic inflammatory myopathy (IIM), for example, has implications for prognosis, future extramuscular organ involvement, and the need for malignancy screening. Magnetic resonance imaging is insufficiently discriminatory to differentiate myoedema in the context of IIM from that seen with vasculitis. Positron emission tomography has most utility for detection of large-vessel vasculitis,4 whereas the intramuscular vessels are small to medium sized. Muscle biopsy for the detection of vasculitis has the benefit of being a generally safe, minimally invasive, and high-yield investigation. Percutaneous and open techniques are available for muscle sampling, and the overall complication rate is less than 3%.5 In contrast, peripheral nerve biopsies, which are well recognized in the workup of vasculitis, result in near-universal sensory deficits, with one in five patients additionally experiencing chronic pain.6 The concluding statement by Brikman et al recapitulates our clinical practice recommendations: muscle symptoms in the setting of raised markers of inflammation, with or without elevated serum CK levels, should prompt consideration of muscle vasculitis. We agree the diagnostic possibilities for this clinical presentation are broad and should include autoinflammatory (including Familial Mediterranean Fever), autoimmune, and infectious etiologies. Muscle biopsy has an established safety profile and is a key investigation to identify vasculitis, without which the cases of IMV we have described1 would have been missed. Disclosure form. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.