C1Q NEPHROPATHY IN CHILDREN: A CASE SERIES.

C1q nephropathy is a controversial disease, usually evident within the transitional spectrum from minimal change nephropathy to focal and segmental sclerosis.

The criteria for diagnosing the disease include predominant or co-dominant deposits of C1q in immunofluorescence and occasionally it can be part of full house nephropathy.

The series of pediatric cases described to date show overlapping and non-specific forms of clinical presentation, which can vary from hematuria and/or proteinuria, to macroscopic hematuria or mixed nephritic/nephrotic syndrome symptoms.

We describe the cases of six pediatric patients with a diagnosis of C1Q nephropathy. 

We document the clinical characteristics, pathological findings and evolution of patients diagnosed with C1Q nephropathy, who presented to our unit in the last 10 years.

- Patient 1: A 1 year old male patient with nephrotic syndrome.

He initially underwent steroid treatment with good response. Subsequently he had multiple relapses, without response to steroids.

Immunological laboratory (C3, C4, ANA, Anti DNA, ANCA) was performed, within normal parameters and Renal Biopsy Puncture: Diffuse sclerosing glomerulonephritis. Immunofluorescence pattern corresponding to C1Q Nephropathy.

He received cyclosporine for one year with subsequent remission of nephrotic syndrome.

- Patient 2: A 2 years old female patient presented with significant hematuria and proteinuria. Preserved renal function and immunological laboratory (C3, C4, ANA, Anti DNA, ANCA) were confirmed, within normal parameters.

A renal puncture biopsy was performed: Mesangiocapillary proliferative glomerulonephritis with sclerosing lesions with full house immunofluorescence pattern with C1Q co-dominance.

She underwent treatment with cyclosporine, with partial response of proteinuria.

-Patient 3: A 7 years old female patient with symptoms compatible with nephrotic syndrome, who initially behaved as a corticosteroid dependent patient. She underwent treatment with mycophenolate and rituximab, achieving clinical stability for 2 years. She had a new relapse, so treatment with steroids was started again, with no response. Since he was assumed to be corticosteroid-resistant, it was decided to perform a renal puncture biopsy.

Renal biopsy: Proliferative glomerulonephritis with full house pattern with C1Q codominance. She was treated with cyclosporine, with no response to treatment.

-Patient 4: A 5 years old female patient who was consulted due to abdominal pain, a urine analysis was requested where albuminuria and microhematuria were confirmed. Her relevant history was a father with chronic kidney disease on hemodialysis, without an etiological diagnosis.

Due to this history, a renal puncture biopsy was performed: Focal and segmental sclerosis with immunofluorescence with predominant C1Q deposition.

Treatment with corticosteroids was indicated, achieving remission of these findings.

- Patient 5: A 5 years old female patient consulted the emergency unit due to respiratory distress, with a diagnosis of acute lung edema, she was admitted to the Intensive Care Unit. In this context, a laboratory was performed where a drop in glomerular filtration rate of 8 ml/min/1.73 m2 was confirmed, and an ultrasound was performed where kidneys were small for age, without corticomedullary differentiation.

Once the clinical picture was stabilized, a renal biopsy was performed: focal and segmental glomerulosclerosis, with immunofluorescence with predominant C1Q deposition. Initial treatment was performed with intravenous corticosteroids and subsequently with cyclophosphamide, without response.

- Patient 6: A 3 years old female patient presented with a diagnosis of nephrotic syndrome, without response to corticosteroids. An immunological laboratory (C3, C4, ANA, Anti DNA, ANCA) was performed, within normal parameters.

Since it was assumed to be corticosteroid-resistant nephrotic syndrome, a renal puncture biopsy was performed. Pathological diagnosis: Focal and Segmental Sclerosis, Immunofluorescence with C1Q codominance.

With these results, treatment with cyclosporine was started, without response.

C1Q nephropathy is an anatomopathological entity with different forms of presentation, which may require different immunosuppressive therapeutic schemes according to its evolution. In our report, results similar to reported pediatric case series were obtained, demonstrating the heterogeneous clinical spectrum of this entity.