Takayasu Arteritis Unveiled by Nephrotic Syndrome Due to AA Amyloidosis

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A 33-year-old female, presented with bilateral pedal edema, progressive facial puffiness for the last 6 months, and generalized body swelling with exertional dyspnea over the past month. Examination revealed pitting edema, ascites, and absent left radial and brachial pulses, with diminished lower limb pulses. Blood pressure was 130/84 in the right upper limb, non-recordable in the left upper limb, and 100/70 in both the lower limbs.

Laboratory findings showed serum creatinine 0.79 mg/dL, albumin 2.0 g/dL, 24-hour urine protein 3.27 g, and cholesterol 555 mg/dL. Renal biopsy demonstrated glomerular and vascular amyloid deposits, confirmed as AA type [Figure 1]. CT angiography revealed >90% stenosis of the left subclavian and common carotid arteries and diffuse intimal thickening of the aortic arch and descending aorta [Figure 2]. The diffuse intimal thickening on CT suggests active disease. The abdominal aorta and its branches, including the renal arteries, were unaffected. Inflammatory markers were mildly elevated (CRP 5.0 mg/L, ESR 30 mm/hr).

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Figure 1: (a) Extensive glomerular and vascular amyloidosis showing amorphous, eosinophilic deposits within glomeruli (red arrow) and vessel walls (blue arrow). Hematoxylin and eosin, 200x. (b) Positive staining for AA amyloid, confirming secondary (AA) amyloidosis (red arrow). Immunofluorescence, 200x.

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Figure 2: (a) 3D volume-rendered computed tomography angiography demonstrating critical (90–95%) stenosis at the origin of the left subclavian artery (dashed arrow) and at the proximal segment of the left common carotid artery (solid arrow). The abdominal aorta and its branches, including the renal arteries, were unaffected. (b) Axial computed tomography image showing diffuse intimal thickening of the descending thoracic aorta (white arrow).

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A diagnosis of active Takayasu arteritis with renal AA amyloidosis was established. She was started on oral prednisolone (1 mg/kg/day) in combination with methotrexate. Angiotensin receptor blockers were initiated.

Takayasu arteritis is a chronic granulomatous large vessel vasculitis affecting the aorta and its major branches. The disease is often diagnosed with well set in vascular changes leading to ischemic symptoms. The renal presentation is usually renovascular hypertension secondary to renal artery stenosis. It is unusual for Takayasu arteritis to develop nephrotic syndrome due to secondary amyloidosis, and extremely rare at the initial presentation. Fewer than 20 cases of Takayasu arteritis associated with AA amyloidosis have been reported. There are only five published cases where Takayasu arteritis had secondary AA at the initial presentation [Table 1].^1-4 In our case, hypertension was absent because the renal arteries were not involved. This case highlights the importance of considering Takayasu arteritis in the evaluation of unexplained nephrotic syndrome and performing a peripheral pulse examination.