In summary, PGWG corresponds to an early phase of WG, presenting only with extravascular granuloma. Primarily, ENT, eye, or lung tissues are involved, but any organ may be affected. The diagnosis is made by typical palisading granuloma associated with elevated c-ANCA levels in the patients' serum. The concept of an early granulomatous lesion (PGWG) facilitates the early diagnosis of WG and leads to classification of different forms of disease according to the multistep evolution hypothesis: first PGWG, then localized or limited forms of the disease, and ultimately generalized vasculitis with renal involvement (classical WG). The concept of PGWG forms the basis for future therapeutic trials where folate antagonists are restricted to PGWG, while immunosuppressive treatment is required for the other stages of WG.