Third Department of Internal Medicine, Akita University School of Medicine, Akita, Japan
Keywords: polyangiitis overlap syndrome; renal amyloidosis
Introduction
Systemic vasculitides are classified by the size of affected blood vessels [1]. However, some patients have overlapping features of common forms of systemic vasculitis. Leavitt and Fauci proposed the entity of polyangiitis overlap syndrome (POS) [2]. While systemic vasculitis can cause secondary amyloidosis, there are few well-documented case reports of secondary renal amyloidosis in patients with POS. Here we present a patient with nephrotic syndrome due to renal amyloidosis caused by POS.
Case
A 26-year-old woman was admitted to the hospital on 14 February 2000, because of right facial pain and leg oedema. In 1989, she had acute cholecystitis, and cholecystectomy was performed. Histological examination of the gall bladder showed marked lymphoid hyperplasia without vasculitis. In 1995, she was diagnosed with acute idiopathic interstitial pneumonia, and was treated with methyl-prednisolone (m-PSL) pulse therapy (500 mg/day for 3 days) followed by oral PSL therapy (40 mg/day). It improved completely after treatment. In 1998, she suffered from high-grade fever and abdominal pain. As the angiogram showed occlusions of left upper pulmonary artery and a narrowing of rectal artery without aneurysm, she was diagnosed with pulmonary and rectal arteritis (Figure 1). She was treated with m-PSL pulse therapy (500 mg/day for 3 days) followed by oral PSL therapy (40 mg/day). These symptoms improved, and the angiogram 3 months after treatment demonstrated the complete resolution of polyarteritis. PSL was tapered to 10 mg, and the level of C-reactive protein (CRP) was less than 0.3 mg/dl. From August 1999, her blood chemistry showed an elevation of CRP. She had right facial pain and bloody rhinorrhoea from November 1999. At this time, proteinuria was observed, and progressed to nephrotic syndrome. She had no history of bronchial asthma and eosinophilia during the course.
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CRP was 7.1 mg/dl and serum amyloid A (SAA) 1360 µg/ml (less than 8 µg/ml). The erythrocyte count was 423x104/µl, haemoglobin 10.9 g/dl, haematocrit 35.6%, leukocyte count 12100/µl (neutrophils 70%, monocytes 11%, eosinophils 2%, lymphocytes 17%), and platelet count 55.6x103/µl. The total urinary protein (UP) for 24 h was 5.0 g. The serum total protein (TP) was 6.2 g/dl, albumin 3.0 g/dl, blood urea nitrogen (BUN) 9.0 mg/dl, and creatinine 0.6 mg/dl. Serum immunoglobulins were normal. The rheumatoid factor, ANA, PR-3, MPO-ANCA, and cryoglobulins were negative. Serum complements were within normal limits. Circulating immune complexes were not detected. Soluble interleukin-2 receptor was 109 U/ml (135483 U/ml). A chest CT scan showed nodules with small satellite lesions in the left upper lobe. Cultures of sputa were negative. A head MRI showed a tumourous lesion with bone destruction in the right maxillary sinus (Figure 2).
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Discussion
Our patient had experienced various diseases including cholecystitis, interstitial pneumonia, and polyarteritis, and then suffered from sinusitis, pulmonary consolidation, uveitis, and nephrotic syndrome caused by secondary amyloidosis. The clinicopathologic characteristics do not fit into any distinct forms of systemic vasculitis. The clinical manifestations of our patient may mimic those of Wegener's granulomatosis (WG) [3]. However, we could not find necrotizing granulomatous vasculitis on biopsy of the maxillary sinus and kidney or PR-3 ANCA in her serum. We therefore could not diagnose WG. Leavitt and Fauci [2] described POS in several patients with systemic vasculitides which do not fit precisely into any classification, but which have overlapping features of classic polyarteritis nodosa, allergic angiitis, and granulomatosis, WG, Takayasu' arteritis, and the hypersensitivity vasculitis. As our patient had various clinicopathological manifestations, which did not fulfil the criteria for distinct systemic vasculitis, we diagnosed her as POS.
In our patient, a renal biopsy showed AA-type amyloidosis. To our knowledge, there are no case reports of renal amyloidosis due to POS. In 1998, our patient had polyarteritis and was treated with PSL. The level of CRP was reduced to the normal range until July 1999. However, the occurrence of secondary amyloidosis indicates that there was a continued production of the precursors of amyloid proteins called SAA, due to polyarteritis. The discrepancy between the level of CRP and that of SAA had been described in patients with SLE, scleroderma, interstitial pneumonia, and vasculitis [4]. It is therefore important for patients with autoimmune diseases including POS, to measure and monitor SAA during the course of the disease.
Gertz and Kyle [5] analysed the cause of death in patients with secondary amyloidosis, and reported that most of these patients died of renal failure or complications of dialysis. Therefore, effective treatment is necessary for patients with secondary amyloidosis. We reported previously that a patient with rheumatoid arthritis (RA) had nephrotic syndrome caused by secondary renal amyloidosis [6]. This patient reached remission of the nephrotic syndrome approximately 18 months after combined treatment with PSL and methotrexate. Several similar cases are described in the literature. It may take 13 years to wash out amyloid depositions from injured glomeruli accompanied by RA, as the production of SAA can be suppressed by decreasing RA activity under effective treatment. We therefore need to treat patients with renal amyloidosis complicated by POS for long periods of time to observe a remission.
Notes
Correspondence and offprint requests to: Atsushi Komatsuda, MD, Third Department of Internal Medicine, Akita University School of Medicine, 1-1-1 Hondo, Akita city, Akita 010, Japan. Email: komatsud{at}med.akita\|[hyphen]\|u.ac.jp
References