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The potential for vasculitis to affect single organs has become increasingly recognized. This has been defined as vasculitis in arteries or veins of any size in a single organ that has no features that indicate that it is a limited expression of a systemic vasculitis. Examples include isolated aortitis, testicular vasculitis, vasculitis of the breast, isolated cutaneous vasculitis, and primary CNS vasculitis. In some instances, this may be discovered at the time of surgery such as orchiectomy for a testicular mass where there is concern for neoplasm that is found instead to be vasculitis. Some patients originally diagnosed with single-organ vasculitis may later develop additional manifestations of a more systemic disease. In instances where there is no evidence of systemic vasculitis and the affected organ has been removed in its entirety, the patient may be followed closely without immunosuppressive therapy. In other instances, such as primary CNS vasculitis or some patients with isolated cutaneous vasculitis, medical intervention is warranted.