Nephrotic syndrome with renal vein thrombosis and adrenal haematoma

Clinical History

Man with atherosclerotic risk factors (smoking, hypertension, dyslipidaemia), history of cerebral ischaemia from patent foramen ovale treated by occlusion. Presented to emergency with worsening left-sided thoracic and dorsal pain for 3 weeks, unresponsive to medications, plus dysuria. Urgent laboratory tests revealed increased C-reactive protein, hypoalbuminaemia (22 g/L, normal range 35-50).

Imaging Findings

Emergency pulmonary CT-angiography (Fig. 1) excluded acute aortic diseases, pulmonary embolism and active pleuropulmonary lesions. Incidentally, a 4x3 cm nonenhancing hyperattenuating (55 Hounsfield units) left adrenal gland enlargement was detected, with associated periadrenal fat stranding and unspecific hypoechoic appearance at ultrasound (Fig. 2).
Meanwhile, nephrotic syndrome (NS) was clinically diagnosed on the basis of consistent laboratory findings, particularly high proteinuria. Glomerular filtration rate was within normal limits.
Five days later abdominal CT (Fig. 3) showed persistent left adrenal enlargement with slightly more demarcated margins, minimal decrease of both attenuation and periadrenal fat stranding. Additionally, extensive thrombosis of the dilated left renal vein was detected, partially extending into the inferior vena cava lumen. Clinical-radiologic consultation interpreted these findings as consistent with NS-related thrombosis with secondary adrenal haemorrhage from venous congestion.
After treatment with diuretics and low-molecular-weight heparin, the patient improved clinically. Follow-up CT (Fig.4) showed near-complete regression of both adrenal haematoma and venous thrombosis.

Discussion

Nephrotic syndrome (NS) includes proteinuria exceeding 3.5 g/day with associated hypoalbuminaemia, hyperlipidaemia and peripheral oedema, and may be related to primary glomerular diseases, secondary to systemic disorders such as diabetes and lupus erythematosus, or represent an adverse effect of medications, particularly nonsteroidal anti-inflammatory drugs. NS is characterised by a poorly understood, multifactorial hypercoagulable state including urinary loss of procoagulant proteins, elevated plasma level of fibrinogen and other clotting factors, mild thrombocytosis and platelet hyper-reactivity. As a result, intravascular blood coagulation represents the commonest, potentially severe complication of NS which may affect the veins and rarely the arteries [1-5].
Overall, thrombotic events occur in approximately 25%-38% of adult patients. The risk is further increased in patients with membranous nephropathy compared to other glomerular histologies, and by other factors such as high proteinuria, hypoalbuminaemia, age over 60 years, altered glomerular filtration rate, classic atherosclerotic factors. Thromboembolism generally occurs early (within the first 6 months) in the NS course [1-4, 6].
The commonest thrombotic complications include deep venous thrombosis, pulmonary embolism (PE, 35%) and renal vein thrombosis (RVT, 22%). PE and RVT are often associated, as nearly 75% of patients with RVT have also PE, usually poorly or not symptomatic. RVT sometimes manifests with flank pain and haematuria, resembling acute renal colic. Less commonly, thrombosis affects the splenic and portal veins, cerebral venous sinuses and internal jugular veins [1, 7-9]
In RVT, ultrasound may show enlarged kidney with hypoechoic cortex. Contrast-enhanced CT or MRI are warranted, as they effectively depict the dilated renal veins containing opacification defects corresponding to thrombi, with (nearly 50% of cases) or without extension into the inferior vena cava. Left-sided involvement is slightly more frequent. Additional imaging findings include thickened Gerota’s fascia, abnormal renal enhancement with prolonged corticomedullary discrimination, delayed or persistent nephrogram, delayed or absent pyelocalyceal opacification [7, 10].
As this case exemplifies, RVT may occasionally cause spontaneous adrenal haemorrhage (AH) from acute increase of intra-adrenal venous pressure, which appears as non-enhancing, roundish hyperattenuating enlargement, plus periadrenal blood or fat stranding. Non-traumatic AH is very rare, usually secondary to anticoagulation, bleeding diathesis, stress, sepsis or underlying tumours [11-13].
Prophylaxis with modern anticoagulants decreases the NS-related morbidity and mortality. When thromboembolism occurs, treatment is the same as in non-nephrotic patients, with heparin followed by warfarin anticoagulation for at least 6 months or until NS remission. Renal function loss is uncommon (10-15% of cases) [1, 3].

Differential Diagnosis List

Final Diagnosis

Nephrotic syndrome with renal vein and inferior caval thrombosis, adrenal haematoma.

URL:	https://www.eurorad.org/case/13886
DOI:	10.1594/EURORAD/CASE.13886
ISSN:	1563-4086