PET-CT and polyarteritis nodosa-associated artery aneurysms

Learning points for clinicians Polyarteritis nodosa is a systemic necrotizing vasculitis, which can cause multiple aneurysms of medium-sized arteries. While the clues for its diagnosis are often difficult to detect, fluorodeoxyglucose-positron emission tomography can be an option to identify local inflammation sites in the whole body, which can help in early diagnosis and treatment. A 78-year-old man visited a clinic complaining of scrotal enlargement. He was diagnosed with epididymitis, administered ceftriaxone for a week and levofloxacin for a week and the enlargement resolved; however, his C-reactive protein was still high (18.98 mg/dl); therefore, he was admitted to our hospital for further evaluation. He was hepatitis B negative and no significant findings were recognized on contrast-enhanced whole body computed tomography (CT) on day 1 (Figure 1A). Positron emission tomography (PET) CT on day 24 showed multiple pancreaticoduodenal artery aneurysms (PDAAs). The largest aneurysm shown in fluorodeoxyglucose (FDG)-PET CT was 32 mm in diameter with FDG accumulation (SUVmax 5.0, Figure 1B) and was retrospectively found to be 16 mm on the day 1 CT (Figure 1A). The aneurysms had enlarged on the contrast-enhanced CT on day 30 (Figure 1C); therefore, the largest aneurysm was embolized with n-butyl-2-cyanoacrylate on day 31 via interventional radiology (IVR). The patient was diagnosed with classical polyarteritis nodosa (PAN) with microaneurysms found on angiography according to the classification algorithm developed by Watts et al.1 Oral prednisolone 1 mg/kg body weight was started on day 36, and all aneurysms had decreased or disappeared on CT by days 50 and 127 (Figure 1D and E) without rupturing. (A) The largest aneurysm in contrast-enhanced CT images taken on day 1. (B) PET on day 24 showing FDG accumulation. (C) CT images on day 30. (D) Day 50 (19 days after IVR treatment). (E) Day 127 (96 days after IVR treatment). Aneurysms of the pancreatic artery and PDAAs are rare and account for only 2% of all splanchnic artery aneurysms.2 Only three publications referring to PDAAs related to PAN were found3,–5; two of the described cases3,4 were ruptured, whereas the remaining case5 was successfully treated by IVR and surgical repair. To the best of our knowledge, this is the fourth report of PDAAs related to PAN, and the second case successfully treated with both IVR and immunosuppressants before aneurysm rupture. Our case was diagnosed with PAN by rapid expansion of the aneurysms and FDG accumulation in PET-CT, which indicated the existence of local inflammation of the aneurysm. One article described diagnosis of PAN-related popliteal vasculitis with FDG-PET6; however, to our knowledge, this is the first documented case in which FDG-PET was the clue for diagnosis of PAN and led to successful treatment before aneurysm rupture. FDG-PET could be useful for early diagnosis of PAN. The patient consent for publication has been obtained from the patient and the patient’s proxy (daughter). Conflict of interest: None declared.