Immunopathologic and histologic studies on benign recurrent hematuria. Clinicopathologic similarities with IgA nephropathy.

From a series of 152 renal biopsy specimens examined by light, immunofluorescence, and electron microscopy, nine specimens were identified as being from patients with BRH. Histopathologic changes in renal biopsy specimens from most of the 9 patients consisted of either normal or slightly proliferative glomerulonephritis. Characteristic alterations were observed by electron microscopy, which showed the presence of small amounts of electron-dense deposits within the mesangium. In addition, immunofluorescent staining of peripheral blood lymphocytes from patients with BRH and their family members showed an increase of IgA-bearing peripheral blood lymphocytes, and the emergence of microhematuria among the families of patients with BRH indicates that some familial factors may be involved in the development of BRH and IgA nephropathy, which suggests that these two disorders may be closely related.