Spontaneous perinephric hemorrhage (Wunderlich syndrome) secondary to polyarteritis nodosa: Computed tomography and angiographic findings.

We report the case of a young man who presented with spontaneous left perinephric hematoma and per-rectal bleeding. Evaluation revealed renal and superior mesenteric arterial aneurysms secondary to polyarteritis nodosa (PAN). Computed tomography and angiographic findings are presented. The aetiology of spontaneous perinephric hemorrhage along with relevant features of PAN are discussed.

Spontaneous perinephric hematoma is a rare entity with malignancies being the most common cause.[1] Vasculites are the next most common cause, and of these polyarteritis nodosa (PAN) accounts for most cases.[1] We report the case of a young man who presented with spontaneous left perinephric hematoma and per-rectal bleeding. Evaluation revealed renal and superior mesenteric arterial aneurysms.

CASE REPORT

A 20-year-old boy presented to the emergency department with sudden onset severe left flank pain for a week and no associated vomiting or urinary symptoms. He had a history of per-rectal bleeding 6 months earlier for which he was evaluated elsewhere. He had noticed a weight loss of 4 kg over these past 6 months. Examination was unremarkable. Blood investigations were unremarkable except for hemoglobin of 9.3 g%. Urinalysis was normal. An ultrasound done elsewhere the previous day was suggestive of a left perinephric mass, hence a contrast enhanced computed tomography (CT) of the abdomen was performed. It revealed an 8 × 7 cm hyperdense lesion in the perinephric space displacing the kidney anteriorly, with an intensely enhancing lesion adjacent to the hemorrhage, indicating an arterial aneurysm with surrounding hemorrhage [Figure 1]. Subsequently, he underwent renal angiography. It revealed multiple small left renal arterial aneurysms with no active bleeding [Figure 2a]. It also revealed similar aneurysms in the superior mesenteric and lumbar arteries [Figure 2b]. Further evaluation revealed a raised erythrocyte sedimentation rate and C-reactive protein. Anti-nuclear antibodies, hepatitis B and C serology were negative, and complement levels were normal. A diagnosis of PAN was made and he was started on steroids and mycophenolate mofetil, as well as anti-hypertensive medication. He was well at 9 months follow-up and CT angiogram showed no beading of the renal vasculature [Figure 3].

Figure 1

Computed tomography of the abdomen showing perinephric hematoma (arrow) with adjacent intensely enhancing lesion suggestive of an aneurysm (arrowhead)

Figure 2

Abdominal arteriography (a) left renal arteriogram showing multiple small aneurysms involving segmental and interlobar branches of renal artery (arrows) (b) aortogram showing involvement of superior mesenteric and lumbar vasculature (arrows)

Figure 3

Follow-up computed tomography angiogram with no beading of renal vasculature (arrows)

DISCUSSION

Spontaneous perinephric hemorrhage (Wunderlich syndrome) is a rare condition with a wide-ranging etiology. Zhang et al. in their meta-analysis reported on 165 such cases.[1] Of these, 101 (62.2%) were secondary to the rupture of renal tumors, with angiomyolipoma being the most common cause. Vasculitis accounted for 28 cases, and PAN was the cause in 20. They reported five cases of bilateral spontaneous hemorrhage and all of these were secondary to PAN.[1]

PAN is a multi-system necrotizing vasculitis that involves small and medium sized vessels. The kidneys are affected in 80% cases with hypertension, proteinuria and ultimately renal functional deterioration being the most common manifestations.[234] Spontaneous perinephric hemorrhage is a rare, but potentially devastating complication of PAN. About 60 cases have been reported in the literature.[2] It is secondary to the rupture of arterial aneurysms that usually involve the renal artery, and its segmental and interlobar divisions.[3] Nephrectomy is associated with a high mortality rate (50%) in the acute setting.[2] Angiography with selective embolization allows preservation of renal parenchyma and is now the treatment of choice in cases of active bleeding.[2] A reduction or resolution in aneurysms has been noted following immunosuppressive therapy and is probably due to the decline in inflammation of the vessel wall.[5]

Per-rectal bleeding is an uncommon manifestation (<4%) and Pagnoux et al. identified gastrointestinal manifestations, and the need for a surgical consult as an independent predictor of mortality in PAN.[4]