Clinicopathological significance of light chain deposition in IgA nephropathy.

BACKGROUND: Clinicopathological significance of light chain deposition in IgA nephropathy and the relation of monotypic IgA deposition to bone marrow abnormalities are important issues to be clarified. METHODS: We retrospectively investigated light chain deposition in 526 patients with IgA nephropathy. We divided the patients into 5 groups according to the balance of intensity of both light chain deposition: lambda monotypic, lambda dominant, polytypic, kappa dominant and kappa monotypic. Clinicopathological parameters were compared among the groups. The relation of monotypic IgA deposition to hematological malignancy was also evaluated. RESULTS: The prevalence of monotypic IgA deposition was 6.3%, 33 patients (21 lambda and 12 kappa). Thirty-two (4.0%) and 10 patients (1.9%) were classified into lambda and kappa dominant groups, respectively. Polytypic IgA deposition was observed in 455 patients (85.7%). Age of onset, age at biopsy, urinary protein creatinine ratio, the percentage of global glomerulosclerosis, and the degree of IgA and C3 deposition were different among the groups. However, there was no gradual difference according to the groups. No patient with monotypic IgA deposition showed hematological abnormality at biopsy and during follow-up. CONCLUSIONS: The prevalence of IgA monotypic deposition was extremely low. Clinicopathologically, we could not differentiate patients with monotypic IgA deposition from those with polytypic one and no hematological disorder was documented in patients with monotypic IgA deposition. Whether IgA nephropathy with monotypic IgA deposition and that with polytypic one is the same entity or not, and relation between monotypic IgA deposition and hematological malignancy should be clarified by further investigations.

Focal segmental glomerulosclerosis in a patient with isolated ACTH deficiency and reversible hypothyroidism.

A 23-year-old man was admitted to our hospital for fatigue, anorexia, proteinuria, and peripheral edema. Proteinuria was first pointed out at the age of 15, but no further studies were performed. Six years prior to admission, the patient noted becoming easily fatigued. Laboratory tests on admission showed marked peripheral eosinophilia (29.2%, count: 1,071/microL) and proteinuria. Endocrinological studies revealed isolated adrenocorticotropic hormone deficiency with primary hypothyroidism, but a lack of autoimmune thyroiditis. Renal biopsy showed focal segmental glomerulosclerosis. Hydrocortisone therapy (30 mg/day) for isolated adrenocorticotropic hormone deficiency resulted in marked improvement of adrenal and thyroid functions, and amelioration of proteinuria (from 2.8 to 1.0 g/day) over a two-month period. Renal function remains normal at five years after the start of hydrocortisone treatment. The findings suggest that both hydrocortisone therapy and normalized thyroid hormone status played a pivotal role in the improvement of proteinuria associated with focal segmental glomerulosclerosis.