Immunotactoid glomerulopathy in a child with Down syndrome

A case of juvenile-onset fibrillary glomerulonephritis diagnosed by mass spectrometry and immunohistochemistry of DNAJB9

Fibrillary glomerulonephritis (FGN) is a rare glomerular disease. FGN is characterized by the deposition of randomly arranged, nonbranching microfibrils in the mesangium and glomerular basement membrane. The discovery of DNAJ homolog subfamily B member 9 (DNAJB9) in 2017 was a breakthrough, and DNAJB9 has been proven to be extremely useful for the definitive diagnosis of FGN. While FGN often occurs in middle-aged individuals, this case was diagnosed at a relatively young age of 17. We performed renal biopsy, and light microscopic study revealed mesangial proliferation with expansion and subepithelial deposits. Electron microscopic study showed glomerular deposition of randomly oriented nonbranching fibrils with a mean of 20 nm. However, direct first scarlet stain for amyloidosis was weakly positive. Therefore, we confirmed the diagnosis of FGN and eliminated the presence of amyloidosis with mass spectrometry. This is the first case in Japan in which the complication of amyloidosis was ruled out with mass spectrometry and FGN was diagnosed using immunostaining and mass spectrometry of DNAJB9. We began treatment with cyclosporine A. One and a half years after the start of the treatment, kidney function continues to be normal.

Acquired glomerular lesions in patients with Down syndrome

The long-term survival of persons with Down syndrome has dramatically increased over the past 50 years. There are no studies addressing the spectrum of glomerular lesions in these patients. We reviewed the clinical-pathologic characteristics of 17 patients with Down syndrome who underwent renal biopsy. The cohort consisted of 12 whites and 5 African Americans with mean age of 29 years (range, 6-45 years). History of hypothyroidism was present in 8 patients. Renal presentations included renal insufficiency (15 patients, mean serum creatinine 3.4 mg/dL), proteinuria (all patients, including 3 with nephrotic syndrome, mean 24-hour urine protein 4.2 g), and hematuria (14 patients, including 4 with gross hematuria). The glomerular diseases found on biopsy were IgA nephropathy (n = 5 patients), focal segmental glomerulosclerosis (n = 4), membranoproliferative glomerulonephritis (n = 2), acute postinfectious glomerulonephritis (n = 2), pauci-immune crescentic glomerulonephritis (n = 2), membranous glomerulonephritis (n = 1), and lupus nephritis (n = 1). Follow-up (mean, 47 months; range, 2-141 months) was available on 16 patients (94%). Two patients (1 with membranous glomerulonephritis and 1 with acute postinfectious glomerulonephritis) had complete remission; 8 patients (4 with IgA nephropathy, 2 with focal segmental glomerulosclerosis, 1 with lupus nephritis, and 1 with acute postinfectious glomerulonephritis) had chronic kidney disease; and 6 patients (2 with pauci-immune crescentic glomerulonephritis, 2 with membranoproliferative glomerulonephritis, 1 with IgA nephropathy, and 1 with focal segmental glomerulosclerosis) progressed to end-stage renal disease, 4 of whom died. In summary, a wide spectrum of glomerular diseases can be seen in patients with Down syndrome, with IgA nephropathy and focal segmental glomerulosclerosis being the most common. Renal biopsy is necessary to determine the type of glomerular lesion and appropriate treatment.

Fibrillary glomerulonephritis and renal failure in a child with systemic lupus erythematosus

Fibrillary glomerulonephritis (FGN) is a rare immune-mediated glomerulopathy characterized by randomly arranged immunoglobulin (Ig) deposits on electron microscopy. Only seven pediatric cases have been reported, and the incidence in adults is about 1.5%. A 12-year-old boy presented with systemic lupus erythematosus (SLE) with World Health Organization Class IV lupus nephritis. A repeat biopsy carried out due to a poor response to standard immunosuppressive therapy and worsening renal functions revealed diffuse proliferative glomerulonephritis with fibrillary deposits. Despite aggressive immunosuppression with plasmapheresis and rituximab, the patient developed end stage renal disease. This is an atypical pediatric case characterized by SLE-associated FGN and a poor prognosis.

A case of fibrillary glomerulonephritis with unusual IgM deposits and hypocomplementemia

Fibrillary glomerulonephritis (FGN) is rare immune-mediated GN with predominant immunoglobulin (Ig) G deposits, normal serum complement levels, and poor prognosis. The incidence of FGN is less than 1% in the adult population, and only six pediatric cases have been reported in the English literature. A 12-year-old girl presented with acute nephrotic-nephritic syndrome mimicking atypical clinical features of acute poststreptococcal GN (APSGN). Clinical features had completely resolved in 2 weeks, but the serum complement levels remained low. Renal biopsy was done 6 months later, and she was diagnosed as having FGN with unusual IgM deposits. Despite persistently low serum complement levels during the subsequent 3 years, clinical relapse did not develop. This case was an atypical form of FGN characterized by unusual IgM deposits, persistent hypocomplementemia, and good prognosis, which suggests that childhood FGN is not necessarily a disease with poor prognosis.

Pathology of glomerular deposition diseases

In routine diagnosis on renal biopsy, one of the confusing fields for pathological diagnoses is the glomerulopathies with fibrillary structure. The primary glomerulopathies with a deposit of ultrastructural fibrillary structure, which are negative for Congo-red stain but positive for immunoglobulins, include fibrillary glomerulonephritis and immunotactoid glomerulopathy. Several paraproteinemias including cryoglobulinemia, monoclonal gammopathy, and light chain deposition disease as well as hematopoietic disorders including plasmacytoma, plasma cell dyscrasia, and B cell lymphoproliferative disorders involve glomerulopathy with an ultrastructural fibrillary structure. A rare glomerulopathy with fibrillary structure that stains negative for Congo-red as well as for immunoglobulins has been also reported. The pathological diagnoses of these glomerulopathies can include either glomerular diseases, or paraproteinemic diseases, or hematopoietic diseases. The terminology is still confusing when glomerular diseases can be combined with paraproteinemic diseases and/or hematopoietic diseases. Therefore, the generic term, 'glomerular deposition disease' (GDD), has been proposed by pathologists with a requirement for clinicians to detect autoantibodies, paraproteins as well as to carry out a bone marrow check. An attempt has been made to rearrange the diseases with related disorders of fibrillary deposits, based on detailed clinical and pathological finding and to elucidate the correlation between GDD, paraproteinemia, and hematopoietic disorder.

Renal involvement in Down syndrome

Kidney disease has not been considered a frequent complication in Down syndrome (DS) patients; a variety of urological abnormalities and glomerulopathies have been reported in this population, and some DS patients develop chronic renal failure (CRF). The aim of this study was to improve the understanding of renal disease in patients with DS, focusing on the incidence and range of kidney and urological abnormalities in a population of DS patients. A cross-sectional study was carried out in DS patients referred from a pediatric genetics unit of a tertiary care center. Medical records were reviewed. A 24-h urine specimen and a blood sample were obtained. Fractional excretion of sodium and potassium, tubular reabsorption of phosphate, urinary excretion of calcium, magnesium, uric acid, creatinine clearance and proteinuria were determined. Ultrasound was performed to evaluate the kidneys and the urinary tract. Laboratory data were reviewed for any possible renal disorder. Sixty-nine patients, aged 12 months to 24 years, were recruited. Pathological findings included three cases of voiding disturbances and a case of hypertension in a 7-year old girl. Eight patients (11.6%) had hyperuricemia without gout. Eighteen patients (24.2%) had hyperuricosuria. Urinalysis revealed three cases of mild proteinuria and two patients with microscopic hematuria. Minor radiological abnormalities were found in five patients (7.3%). Three patients (4.5%) had CRF. Renal disease in patients with DS is not as rare as previously thought, although the majority of findings are of minor relevance. According to the variety of pathologies, and in order to detect early irreversible renal injury, it seems quite reasonable to perform regular monitoring of renal function in these patients.

Urological Manifestations of Down Syndrome

PURPOSE

We identified the urological anomalies seen in patients with Down syndrome.

MATERIALS AND METHODS

We reviewed the literature on Down syndrome and its associated genitourinary pathology.

RESULTS

Associated defects have been reported throughout the genitourinary tract. The most common renal anomalies seen are renal hypoplasia, obstructive uropathy and glomerular microcysts. Decreased creatinine clearance has also been noted. Developmental anomalies, such as megaureter and vesicoureteral reflux, have been reported. Dysfunctional voiding and urinary retention have been found in these patients. Posterior urethral valves and hypospadias have also been seen. The testicular abnormalities most frequently reported are cryptorchidism, testicular cancer and infertility.

CONCLUSIONS

Improved understanding and identification of the various urological anomalies associated with Down syndrome will aid in the care of these patients. In addition, an awareness of perioperative issues will further facilitate a smooth clinical course.

Posterior urethral valves in patients with Down syndrome

Renal and urological anomalies in Down syndrome (DS) have received little attention compared with the nephrourological findings described in other chromosomal abnormalities. Renal hypoplasia, hydroureteronephrosis, ureterovesical and ureteropelvic junction obstruction, and vesicoureteral reflux, but not posterior urethral valves, have been associated with DS. We report the occurrence of posterior urethral valves in three male infants with DS at a single institution. All had multiple urological procedures for correction or palliation of obstruction. Children with DS may have an increased risk for developing posterior urethral valves and obstructive uropathy. Furthermore, they may also develop chronic renal failure secondary to posterior urethral valves. Therefore, we suggests that infants with DS be screened with ultrasonography for renal and urological abnormalities early in life and, if abnormal, a contrast voiding cystourethrogram be performed to rule out posterior urethral valves or other bladder or urethral abnormalities. A review of the renal and urological anomalies in DS reported in the literature since 1960 is presented.

Anti-neutrophil cytoplasmic antibody associated glomerulonephritis in a patient with Down's syndrome

A 9-year-old boy with Down's syndrome developed a glomerulonephritis associated with crescents and anti-neutrophil cytoplasmic antibodies (ANCA). The patient also had type 1 diabetes mellitus, chronic lymphocytic thyroiditis, and bronchial asthma. Prednisone therapy resulted in an improvement in renal function and a reduction in ANCA titers.