Marius G Pakalniskis, Aaron D Berg, Bruno A Policeni, Lindell R Gentry, Yutaka Sato, Toshio Moritani, Wendy R K Smoker

Wegener granulomatosis has recently been renamed as granulomatosis with polyangiitis (GPA). In this review, we examine the clinical criteria and pathologic and pathophysiologic mechanisms of GPA, with an emphasis on findings encountered in the realm of head and neck imaging. Particular attention is paid to generating an appropriate differential diagnosis, because many of the imaging features of GPA overlap with those of other diseases, most notably lymphoma and sarcoidosis. Recent therapeutic advancements have underscored the importance of the radiologist in suggesting the diagnosis early, resulting in earlier treatment and decreased patient morbidity. This is particularly true for the head and neck manifestations of GPA; although they are less common, they often herald a refractory disease course that requires aggressive immunosuppressive therapy. Knowledge of common and uncommon imaging findings enables the radiologist to diagnose GPA early enough to start treatment promptly and reduce patient morbidity. Although there are no reliable pathognomonic imaging features for GPA, the present article attempts to identify patterns of disease that are suggestive of the disease. The diagnosis ultimately relies on a constellation of radiographic findings, laboratory values, and accurate clinical history.