When the patient represented she had an elevated C-reactive protein 168 mg/L (normal: <12), erythrocyte sedimentation rate 76 mm/hr (0-12) and alkaline phosphatase 162 U/L (30-130). All her other blood results were normal. Rheumatoid Factor, ANCA and HLA B27 were negative as were blood cultures and viral serologies. Hepatobiliary scintigraphy was requested to investigate hepatobiliary function (Figures ​(Figures1,1, ​,2).2). The study was performed with 220 MBq (5.9 mCi) Tc-99m disofenin. The vascular phase appeared normal. The parenchymal phase showed an enlarged left lobe of the liver. Bile production was normal with rapid appearance in the intrahepatic ducts and normal passage of bile into the bowel. However, the gallbladder filled slowly during the study. An outpatient computed tomography scan which had been performed prior to admission showed a thickened gallbladder wall with surrounding fluid but no evidence of stones or duct dilatation (Figure ​(Figure33).

Based on these findings and the clinical picture a laparoscopic cholecystectomy was performed. The postoperative recovery was unremarkable and the patient was discharged two days later and subsequently had no further right upper quadrant pain. Clinical follow-up one month later showed that she was still free of abdominal pain but had developed symptoms consistent with mononeuritis multiplex. Polyarteritis nodosa was considered the most likely diagnosis clinically.

Macroscopic examination of the gallbladder showed no gross abnormality. However, microscopic examination revealed a striking vasculitis affecting small to medium sized vessels, predominantly arteries. There was fibrinoid necrosis of many vessels associated with an inflammatory cell infiltrate, composed predominantly of lymphocytes with very occasional eosinophils (Figure ​(Figure4).4). Almost every vessel in the histological sections was affected and some showed thrombotic occlusion. The findings were consistent with polyarteritis nodosa.

Vasculitis is a clinicopathologic process characterized by inflammation of and damage to blood vessels. Polyarteritis nodosa (PAN) can cause specific complaints related to the vascular involvement within a particular organ system which may dominate the presenting clinical picture as well as the entire course of the illness. Involvement of the gastrointestinal tract has a 44% incidence in patients with classic PAN. Clinical manifestations include abdominal pain, nausea and vomiting, bleeding, bowel infarction and perforation, cholecystitis, as well as hepatic and pancreatic infarction. At autopsy 10% of patients with classic PAN have involvement of the gallbladder.

Gallbladder vasculitis of varying aetiology is rare but has been well described in the medical literature [2-13]. Abdominal pain, especially in the right upper quadrant is the most common presenting symptom. Liver function tests may be abnormal but as patients are usually thought to have cholecystitis secondary to cholelithiasis abdominal ultrasound imaging is performed sometimes followed by computed tomography [14]. Following laparoscopic or open cholecystectomy the diagnosis is then made based on the intraoperative and histological evidence.