Temporal artery biopsy in polyarteritis nodosa: a case-based narrative literature review.

Polyarteritis nodosa (PAN) is a systemic necrotizing vasculitis of medium-sized arteries, and histologic confirmation is often challenging. Temporal artery biopsy (TAB) is established for suspected giant cell arteritis (GCA), but is rarely performed in PAN. We describe a 27-year-old Japanese man who presented with melena and acute visual loss in the right eye. Contrast-enhanced computed tomography revealed multiple visceral aneurysms involving the hepatic, renal, and mesenteric arteries, with active extravasation from a jejunal artery aneurysm. Ophthalmologic evaluation confirmed central retinal artery occlusion. Renal biopsy showed no evidence of vasculitis. During hospitalization, he developed a new medullary infarction, and re-examination revealed induration of the superficial temporal artery. TAB was therefore performed and demonstrated neutrophil-rich necrotizing arteritis with fibrinoid change, supporting the diagnosis of PAN. To contextualize the diagnostic role of TAB in PAN, we reviewed the literature and identified 21 TAB-confirmed cases including this patient. Most reported TAB-confirmed PAN cases underwent biopsy because GCA was initially suspected, and the histopathologic findings were heterogeneous; a neutrophil-predominant necrotizing pattern with fibrinoid change-particularly in the absence of multinucleated giant cells-may prompt reconsideration beyond GCA. The diagnostic yield of TAB in unselected PAN has not been studied, and the available evidence is limited to case reports and TAB-based cohorts. Nevertheless, TAB may be considered a pragmatic option for histologic confirmation when conventional biopsy sites are impractical or high risk, particularly in the presence of cranial ischemic manifestations or temporal-artery abnormalities.