#2889 Multiple renal tumors as an atypical clinical manifestation of granulomatosis with polyangiitis
Authors: Leśniak Ksymena , Rymarz Aleksandra , Niemczyk Stanisław 
Published: May 2024

Abstract

Background and Aims
Granulomatosis with polyangiitis (GPA) is a systemic small- vessel vasculitis associated with antineutrophilic cytoplasmic antibody (ANCA), in which kidney involvement often occurs. In some cases the course of vasculitis with kidney involvement is atypical, what complicates the diagnostic process and makes appropriate treatment difficult. Finding nodular masses in the kidneys always causes an oncological concern, while in the differential diagnosis a systemic vasculitis is rarely taken into account, what may lead to an unnecessary nephrectomy.

Method
We present a case of granulomatosis with polyangiitis (GPA) who presented with multiple tumors in the kidneys and adrenal gland.

Results
29-year-old man experienced a sudden disease onset, at the age of 18 years, when due to peripheral oedema, nephrotic grade proteinuria (13.7 g/24 h), hematuria and presence of renal failure markers (serum creatinine 3.4 mg/dL), he was admitted to hospital. A suggestion of a rapidly progressive glomerulonephritis (RPGN) was put forward and a renal biopsy was performed (in the histopathological examination of the kidney, pauci-immune crescentic necrotizing glomerulonephritis was revealed). A treatment with plasmaphereses, high glucocorticosteroid doses and cyclophosphamide pulses was instituted. Haemodialysis therapy was also applied temporarily. ANCA and anti-glomerular basement membrane (GBM) antibodies were determined to give negative results. As a result of the remission-inducing treatment, an improvement of the renal function was obtained (serum creatinine 1.6-1.9 mg/dL). In spite of the remission-maintaining treatment with mycophenolate mofetil (MMF) and oral prednisone, after 10 years again a dramatic renal function impairment occurred, with a necessity of institution of a long-term haemodialysis therapy. Furthermore, on abdominal ultrasound examination multiple focal lesions were found in both kidneys, which rendered a kidney transplantation procedure in the patient impossible. In order to extend the diagnostic procedures, a magnetic resonance imaging (MRI) of the abdominal cavity without contrast agent administration was carried out (in both kidneys disseminated focal lesions were described: non-homogeneous, with moderately enhanced signal on T2-weighted images in the central part, without signs of water diffusion restriction; in the left kidney, of 23 x 22 mm and 19 x 15 mm dimensions; in the right kidney, of 30 x 32 mm, 26 x 22 mm and 22 x 18 mm dimensions. The picture of the lesions was unspecific and atypical. In the differential diagnosis granulomas could not have been ruled out, while disseminated proliferative lesions were less likely. Besides that, in both kidneys cysts of up to 7 mm diameters were present. In the lateral limb of the left adrenal gland a focal lesion was visible, of 23 x 14 mm dimensions, of a structure identical to that of the foci in both kidneys). On high-resolution computed tomography (HRCT) of the chest at the same time, small ground glass areas were found in the lungs. On positron emission tomography/computed tomography (PET/CT) no changes were visualised, suggesting presence of a metabolically active proliferative process. Tests for ANCA, antinuclear antibodies (ANA), anti- double-stranded DNA (dsDNA) antibodies, anti- GBM antibodies were again performed and gave negative results. He was diagnosed with granulomatosis with polyangiitis without ANCA and treated with corticosteroid and intravenous rituximab (4x 787 mg). Three months later, follow-up showed reduced mass lesions in the kidney and adrenal gland by MRI.

Conclusion
The case highlights the atypical clinical presentation of vasculitis and the significance of considering this possibility in differential diagnosis when confronting mass lesions present in the kidney.