56-year-old woman, diagnosed with pSS 13 years previously. She presented with dry syndrome, asthenia and frequent episodes of polyarthritis. During this time, she followed prolonged treatment with non-steroidal anti-inflammatory drugs (NSAIDs) and steroids. In addition, in recent months, methotrexate had been associated with little improvement in symptoms.
Three months after starting dental treatment with dental implants, he was admitted with facial oedema, febrile syndrome and decreased diuresis.
Physical examination revealed deterioration in general condition, blood pressure (BP) of 160/90 mmHg, fever and submandibular oedema with evidence of active infection in the lower dental arch. There was no distal oedema or skin lesions.
Laboratory tests showed Hb 9.2 g/dl, creatinine 2.9 mg/dl, urea 110 mg/dl, normal liver profile, lipid profile, ANCA and immunoglobulins. ANA positive, anti-DNA negative. Low C3 and C4, 46 and 1.6 mg/dl, respectively. Serology for HBV, HCV and HIV negative. Blood cultures negative. ANA, anti-Ro, anti-LA and rheumatoid factor (RF) antibodies remained positive since the diagnosis of SSp. He had also occasionally presented hypocomplementemia. Urine proteinuria (2 g/l) and microhaematuria were observed. Renal ultrasound was normal. The patient developed an afternoon fever, despite antibiotherapy, and oliguria, and dialysis treatment had to be started.
Suspecting acute glomerulonephritis (GN), probably postinfectious, given the history of the mandibular infectious process and hypocomplementemia, a renal biopsy was performed with the following results:
The cylinder for light microscopy contained 8 glomeruli showing diffuse capillary occlusion by thrombi of PAS-positive proteinaceous material. They were accompanied, in some glomeruli, by segmental infiltration of inflammatory cells. The interstitium showed isolated foci of lymphoplasmacytic inflammation and the arteries were unchanged.

Direct immunofluorescence (DIF) showed strong positivity for IgG, IgM, kappa and lambda thrombi, but weaker for C3 and IgA. C1q and fibrinogen were negative. Ultrastructural study was performed at a later stage.

Pathological diagnosis
Glomeruli with massive intracapillary thrombi of immunoglobulins suspected of cryoglobulinemic glomerulopathy associated with SS.