SERONEGATIVE GRANULOMATOUS VASCULITIS IN A YOUNG ADULT: INSIGHTS FROM A RARE CLINICAL PRESENTATION

Vasculitis is a rare group of inflammatory disorders that may affect multiple organs. They are frequently associated with renal involvement, often manifested by active urinary sediment, and many cases present with positive serology. We describe a rare case of seronegative granulomatous small-vessel vasculitis without glomerular involvement, an exceptionally uncommon presentation in adults.

Clinical, laboratory, imaging, and histopathological data were reviewed, with multidisciplinary evaluation guiding diagnosis and treatment.

A 37-year-old man with acute kidney injury was referred to the Nephrology Department. His past medical history included arterial hypertension for almost ten years, childhood asthma (ages 6-13), chronic sinusitis and migraine with aura since age 25. He had been followed exclusively in a private hospital. Previous records showed serum creatinine (SCr) values had been 2.65 mg/dL four months earlier, 1.79 mg/dL three months earlier, and 2.66 mg/dL one month prior to admission, with some episodes of macroscopic hematuria during this period.

At admission, blood pressure was 264/153 mmHg and SCr 2.82 mg/dL, with mild isomorphic erythrocyturia and protein-to-creatinine ratio 0.22. Renal ultrasound showed increased renal echogenicity. CT urography demonstrated a hemorrhagic renal cyst, and CT angiography was unremarkable. Urinary sediment was repeatedly normal throughout hospitalization. As renal function improved and no signs of active disease were present, biopsy was not performed. At discharge, SCr was 2.0 mg/dL and urinary sediment remained normal.

Three months later, he presented with headaches and focal neurologic deficits. SCr was 2.18 mg/dL, with normal urinary sediment. He was admitted to the Neurology Department, where further investigations were performed. Cranial CT revealed nasal polyps and biopsy showed no features of Churg–Strauss syndrome. The patient then reported a prior renal biopsy at a private hospital. The report described rare red blood cell casts, 20–30% interstitial fibrosis and tubular atrophy, epithelioid granulomas with central necrosis in the interstitium, involving small-caliber arteries and arterioles, with fibrinoid necrosis in one vessel. Contrast-enhanced MR angiography demonstrated chronic ischemic lacunae without findings compatible with CNS vasculitis. The neurological symptoms at admission were attributed to migraine with visual, sensory, and aphasic aura.

After multidisciplinary discussion in our Nephrology Department, the final diagnosis was seronegative granulomatous small-vessel vasculitis without glomerular involvement. Induction therapy was initiated with pulse methylprednisolone and cyclophosphamide according to the CYCLOPS protocol. He is currently awaiting initiation of maintenance therapy with rituximab, with serum creatinine (SCr) of 1.84 mg/dL, normal urinary sediment, and no proteinuria. 

Granulomatous vasculitis usually presents with ANCA positivity and glomerular involvement. The absence of glomerular lesions and seronegativity in this patient make the case highly unusual, posing significant diagnostic/therapeutic challenges.
This case highlights that seronegative granulomatous small-vessel vasculitis may present without glomerular involvement, stressing the role of renal biopsy and multidisciplinary evaluation in guiding management.