Diffuse mesangial cell proliferation in focal sclerosing glomerulonephritis.

Morphometrical and clinical investigations were performed in 34 patients with the so-called hypercellular form of focal glomerulosclerosis (FGS), i.e., a form showing clear diffuse mesangial hypercellularity beside focal sclerosis with the light microscopy. This form was compared with focal glomerulosclerosis without remarkable mesangial hypercellularity, with mild mesangioproliferative glomerulonephritis (gn), as well as with normal kidneys. The results were as follows: 1. Morphometrically both the increase in relative mesangial volume as well as in mesangial cell count is statistically significant in the hypercellular form compared with the nonhypercellular form and with controls. Comparison with mild mesangioproliferative gn shows no difference. 2. Even the so-called nonhypercellular form contains more mesangial matrix and mesangial cells than the controls. 3. The frequency of the hypercellular form is higher in males and in older patients. 4. All of our patients with hypercellular FGS had at the time of biopsy manifested nephrotic syndrome. The frequency of additional clinical symptoms (hematuria, hypertension, renal insufficiency) corresponds with the nonhypercellular form, but is different in mild mesangioproliferative gn. 5. Therapeutic response and prognosis is worse in the hypercellular form. The hypercellular form of FGS has to be separated from the nonhypercellular form as a defined entity.