Nephrotic Syndrome with Mesangial-cell Proliferation in
Children—A Distinct Entity?
WILLIAM M. MURPHY, M.D., ALINA F. JUKKOLA, M.D., AND SHANE ROY, III, M.D.
Murphy, William M., Jukkola, Alina F., and Roy, Shane,
III: Nephrotic syndrome with mesangial-cell proliferation in
children—A distinct entity? Am J Clin Pathol 72: 42-47,
1979. Various morphologic patterns have been identified in
renal biopsies of children with the idiopathic nephrotic syndrome. Children with focal segmental glomerulosclerosis have
clinicopathologic features sufficiently distinct to warrant a
separate subclassification. "Immunoglobulin M (IgM) nephropathy" and other morphologic patterns are less well defined.
The clinicopathologic characteristics of eight patients with
the nephrotic syndrome, increased mesangial cellularity on
renal biopsy, and hematuria (mesangioproliferative nephropathy) were evaluated. Response to standardized prednisone
therapy was poor. Of the seven children followed for 7-29
months, only two were in remission at the time of writing,
and each of these had had one prior relapse. The eighth patient was lost to follow-up after one month. Although the number of patients studied was small, there was a strong correlation between degree of mesangial-cell proliferation and failure
of primary treatment. As concepts of the pathogenesis of
idiopathic nephrotic syndrome in children continue to evolve,
the mesangioproliferative lesion should be recognized and
marked for further study. (Key words: Nephrotic syndrome;
Mesangioproliferative nephropathy; Focal segmental glomerulosclerosis.)
Departments of Pathology and Pediatrics,
University of Tennessee Center for the Health Sciences,
Memphis, Tennessee
mune complex deposition or focal segmental glomerulosclerosis. Although mesangial-cell proliferation
in nephrotic patients has been reported in a number of
series, 2 ' 4,101218 few studies have dealt specifically with
this topic. In most instances a homogeneous group,
defined by evaluation of renal biopsies by light microscopy, immunofluorescence, and electron microscopy,
as well as selected clinical criteria, has not been studied. We report the results of analysis of eight cases of
children with mesangioproliferative nephropathy, done
to determine whether the clinicopathologic features
were sufficiently characteristic to warrant classification as a distinct clinicopathologic entity.
Materials and Methods
Of the 147 children in whose cases renal biopsies
were performed between September 1974, and December 1977 at LeBonheur Children's Hospital, 44 (30%)
had the nephrotic syndrome. Eight patients, six boys
and two girls, whose ages ranged from 2 to 15 years, had
hematuria and generalized, diffuse mesangial-cell proliferation as the only morphologic abnormality, with
no evidence of immune-complex deposition by immunofluorescence and electron microscopy. Signs and
symptoms attributable to the nephrotic syndrome had
been present for one week to eight months prior to
admission. Other pertinent data at the time of renal
biopsy are summarized in Table 1.
The definitions of nephrotic syndrome and response
to therapy of the International Study of Kidney Disease in Children were used. 18 Briefly, nephrotic syndrome was defined as proteinuria >40 mg/m 2 /hour,
serum albumin <2.5 g/dl, hypercholesterolemia, and
edema. Patients were treated with 60 mg/m2/day of
prednisone in divided doses for four weeks, followed
by 40 mg/m2/day in divided doses on three consecutive days of seven for an additional four weeks. The
patient was said to have responded when zero to trace
proteinuria (Albustix-Ames®) or quantitative proteinuria of <4 mg/m2/hour was demonstrated on three
ALTHOUGH the idiopathic nephrotic syndrome of
childhood is usually associated with minimal pathologic
changes, various morphologic abnormalities in the kidneys of a significant number of nephrotic children have
been described since the advent of percutaneous renal
biopsy. One of these, focal segmental glomerulosclerosis, gained general acceptance as a distinct clinicopathologic entity with the realization that these lesions identified a group of patients whose disease
tended to be refractory to treatment and who were at
high risk of development of early renal failure. 91117
Recently, reports of less well-defined entities, such as
immunoglobulin M (IgM) nephropathy 3,5 and mesangioproliferative nephropathy, 8 have appeared. For the
purpose of this study, patients with mesangioproliferative nephropathy are distinguished by a triad of (1)
nephrotic syndrome, (2) hematuria, and (3) generalized, diffuse mesangial-cell proliferation without imReceived June 5, 1978; received revised manuscript and accepted
for publication August 1, 1978.
Address reprint requests to Dr. Murphy: Department of Pathology,
University ofTennessee Centerfor the Health Sciences, 858 Madison
Avenue, Memphis, Tennessee 38163.
0002-9173/79/0700/0042 $00.80 © American Society of Clinical Pathologists
42
Vol. 72 . No. 1
43
MESANGIOPROLIFERATIVE NEPHROTIC SYNDROME
Table I. Clinicopathologic Features at Renal Biopsy
Patient
Patient
Patient
Patient
Patient
Patient
Patient
Patient
1
2
3
4
5
6
7
8
Age
(Years)
Race/
Sex
Serum
Albumin
(g/dl)
9
3
8
15
9
2
3
7
W/F
W/F
W/M
W/M
W/M
W/M
B/M
B/M
2.4
1.5
1.7
1.6
2.1
1.9
1.9
1.2
Serum
Creatinine
(mg/dl)
Creatinine
Clearance
(ml/min/
1.73 m2)
Urinary
Protein
(mg/m2/hour)
Urinary
Erythrocytes
High-Power Field
Mesangial
Proliferation
0.5
0.5
0.4
0.9
0.6
0.8
0.5
0.5
179
115
156
122
143
36
136
139
160
236
158
261
132
269
51
129
Numerous
Numerous
40-60
40-60
19-22
15-20
25-35
20-25
1+
1+
1+
1+
2+
2+
2+
3+
Table 2. Clinicopathologic Features at Last Follow-up Examination
Patient
Patient
Patient
Patient
Patient
Patient
Patient
Patient
1
2
3
4
5
6
7
8
Duration
(Months)
Serum
Creatinine
(mg/dl)
Creatinine
Clearance
(ml/min/
1.73 m2)
Urinary
Protein
(mg/m2/hour)
Treatment
Prednisone
(Months)
Cytoxan
(Weeks)
Response*
Relapses
7
1
24
29
8
12
13
23
0.5
—
0.75
0.8
0.6
0.45
—
0.6
122
—
104
185
82
97
—
97
7.5
0
0
127
6.8
285
0
50
6
1
2
15
6
11
2
12
0
0
0
11
0
8
0
8
R
R
R
NR
NR
NR
R
NR
0
0
1
—
—
—
1
—
• R " responder; NR •-• non-responder.
consecutive days during the initial eight weeks of treatment. When proteinuria decreased to <40 mg/m2/hour
but remained >4 mg/m2/hour, the patient was deemed
a non-responder. Relapse occurred when, after an initial response, proteinuria was 2+ to 4+ or >40 mg/
m2/hour on at least three consecutive days.
Hematuria was defined as the presence of three or
more erythrocytes per high-power field on repeated
microscopic examination of urinary sediment. During
the period of this study, quantitative measurements to
identify hematuria were not done. All individuals had
persistent hematuria during the follow-up periods.
In each case, two cores of renal tissue were obtained. One was dissected for examination by light and
electron microscopy, and the remainder was used for
immunofluorescence. Processing was begun within 60
sec after specimen removal. All tissue evaluations were
performed without knowledge of the clinical findings.
Tissue for light microscopy was fixed in either Zamboni's solution or Dubosq-Brazil fluid for three to four
hours, postfixed in 80% alcohol or 10% neutral buffered formalin, respectively, and embedded in paraffin.
Sections 2-4 fjun thick were stained with hematoxylin and eosin, periodic acid-Schiff, periodic acidmethenamine silver, and Masson trichrome reagents.
The tissue was examined in its entirety—24 to 50 sec-
tions per specimen. Tissue for immunofluorescent
microscopy was quick-frozen in liquid nitrogen, sectioned at 4 /um on an Ames® cryostat, and incubated
with various commercially prepared fluoresceinlabeled antisera.* Tissue for electron microscopy was
fixed in 5% glutaraldehyde, postfixed in 1% osmium
tetroxide, and embedded in Maraglas®, Epon 812®, or
Spurr®. Six to 13 blocks were prepared for each specimen. Sections 1 /xm thick were examined for each
block, and representative sections were selected for
examination under a Philips 200® transmission electron microscope. Mesangial cellularity was evaluated
in tissue sectioned at 2-4 //,m for light microscopy
and in tissue cut at 1 /im for electron microscopy. The
former was more useful in determining the distribution of mesangial proliferation, whereas the latter was
more reliable for grading. A mesangial area was considered to include the tissue between capillary loops,
and a semiquantitative grading system was used: 1 + ,
at least three mesangial-cell nuclei per mesangial area;
2+, four mesangial-cell nuclei in at least 75% of mesangial areas; and 3 + , five mesangial-cell nuclei in at
least 75% of mesangial areas.
* Hyland Laboratories, Costa Mesa, California 92626 and Meloy
Laboratories, Springfield, Virginia 22151.
44
MURPHY, JUKKOLA, AND ROY
A.J.C.P. • July 1979
FIGS. 1 to 3. Semiquantitative grading of mesangial
cellularity using l-/*m sections stained with toluidine
blue.
FIG. 1 (upper, left). 1 + : at least three mesangial-cell
nuclei per mesangial area. x400.
FIG. 2 (upper, right). 2+: four mesangial-cell nuclei in
at least 75% of mesangial areas. x400.
FIG. 3 (lower). 3 + :fivemesangial-cell nuclei in at least
75% of mesangial areas. X400.
MESANGIOPROLIFERAT1VE NEPHROTIC SYNDROME
Vol. 72 . No. 1
45
Results
Results at the last follow-up examination are partially summarized in Table 2. All patients had similar
pathologic findings. By light microscopy there was
generalized, diffuse mesangial-cell hyperplasia without
increased mesangial matrix, lobulation, or segmental
sclerosis. Mesangial cellularity was graded 1+ in four
cases, 2+ in three instances, and 3+ in one specimen
(Figs. 1-3). Glomerular basement membranes were
normal, and neither patchy interstitial fibrosis nor
tubular atrophy was observed in the sections examined.
The blood vessels examined were also normal. Antisera specific for human IgG, IgA, IgM, C3, and fibrinreactive products were used in every case, and all reactions were negative. Electron microscopic examination revealed mesangial-cell hyperplasia as well as the
foot process effacement and microvillous transformation of epithelial cells found in heavy proteinuria (Fig.
4). Neither mesangial-cell interposition (basementmembrane splitting) nor dense deposits were identified
in any of the biopsy specimens. The endothelial cells,
glomerular basement membranes, interstitium, tubules, and blood vessels were unremarkable in all sections examined.
Patients were followed for one to 29 months (mean
= 14.5 months) after diagnosis. Proteinuria was determined daily at home by a parent with an Albustix, and
recorded and creatinine clearance was measured
periodically. Of the four patients whose disease responded to the initial eight-week course of prednisone,
relapses occurred in two (Patient 7 and Patient 3) 11
and 22 months, respectively, after completion of
therapy. Both of these individuals had good responses
to a second course of prednisone therapy and are proteinuria-free at the time of writing. Patient 1, an initial
responder, subsequently had a quantitative urinary
protein of 7.5 mg/m2/hour during the seventh month of
intermittent prednisone therapy. Patient 2 was free of
proteinuria after a month of daily prednisone administration but has subsequently been lost to follow-up.
The renal biopsy specimens from three of the initial
responders had 1+ mesangial proliferation, while 2+
mesangial proliferation was shown in one.
In the other four patients, the disease failed to respond during the initial eight-week course of prednisone therapy. Three non-responders received cyclophosphamide for 8 to 11 weeks in addition to alternateday prednisone following the initial prednisone therapy.
There was no significant alteration in their proteinuria.
The creatinine clearance in the case of Patient 6,
which was 60 ml/min/1.73 m2 at the initiation of
cyclophosphamide therapy, had increased to 105 ml/
min/1.73 m2 after 8 weeks of cyclophosphamide ther-
FIG. 4. Ultrastructural changes in glomerulus: mesangial-cell
hyperplasia and foot-process effacement with microvillous transformation of visceral epithelial cells. x2,400.
apy. The renal biopsy specimen of one non-responder
had 1+ mesangial proliferation; two, 2+ mesangial
proliferation; one, 3+ mesangial proliferation. At the
most recent examination none of the non-responders
had. symptoms attributable to the nephrotic syndrome,
none was receiving medication, but each had persistent proteinuria. The apparent decrease in creatinine
clearance of Patient 5 was attributed to an incomplete urine collection, since his serum creatinine had
not changed.
Discussion
The identification of a type of idiopathic nephrotic
syndrome in children associated with mesangial-cell
proliferation on renal biopsy and poor response to
corticosteroid treatment is not a new observation.2,41018
Histologic studies of renal tissue that did not include
immunofluorescent and electron microscopic examination to rule out immune-complex disease has made it
difficult to evaluate these patients. As immunofluorescent and electron microscopic technics began to
delineate subtypes of nephrotic syndrome, entities
such as focal glomerulosclerosis were recognized.
Thus, interest in patients with so-called mesangioproliferative nephropathy has been rekindled. The study
of this clinicopathologic complex is still in the formative stages, and numerous problems in definition and
46
MURPHY, JUKKOLA, AND ROY
classification exist. The infrequent identification of this
histopathologic subtype (2.3 to 5.3% of nephrotic
children),2,61018 variable treatment regimens, and the
short-term follow-up periods reported have hampered
accurate evaluation of the natural history of mesangioproliferative nephropathy. The lack of standardized
definitions of such terms as mesangial-cell proliferation makes comparisons among series difficult.
Many approaches to the evaluation of mesangial cell
proliferation have been used, and all have been, for the
most part, subjective. Short of quantitative morphometry of each glomerulus,1315 a tedious and somewhat impractical procedure, this problem will continue
to exist. In an effort to more closely define mesangialcell proliferation in this series, an arbitrary number of
nuclei per mesangial area on sections of uniform 1ju,m thickness were coded on a scale of 1 to 3+. As is
evident from the figures, all grades describe significant
proliferation. Although the number of patients was
small, there appeared to be a strong correlation between the degree of mesangial-cell proliferation and
initial response to steroid therapy. Of the four responders, three had 1+ mesangial-cell proliferation
in biopsy specimens, compared with 1+ in a specimen
from only one of the four non-responders. In contrast,
of the four biopsy specimens with 2-3+ mesangial
proliferation, three were from non-responders. Given
the poor response to therapy in the group as a whole,
the degree of mesangial-cell proliferation may not be as
important over the long term as its presence.
Idiopathic nephrotic syndrome with mesangial-cell
proliferation and hematuria was associated with a poor
response to therapy in the patients of this study. Of the
seven patients still being actively followed, only two
are currently free of proteinuria, and each of these has
had one relapse. Four patients were initial non-responders, and one individual, Patient 1, an initial
responder, experienced the onset of persistent proteinuria during alternate-day prednisone therapy. This
is in marked contrast to the published experience in
the idiopathic nephrotic syndrome with minimial histologic change, where only 5-10% of patients have disease that fails to respond to initial prednisone therapy. 1'2-4-18
Although the lack of characteristic clinical findings,
immune complexes, and dense deposits clearly rules
out diseases such as poststreptococcal glomerulonephritis, the place of mesangial-cell proliferation in the
pathology of the nephrotic syndrome is controversial.
The most prevalent theory states that mesangial-cell
proliferation, whether occurring de novo or evolving
from minimal-change disease, represents a stage in a
spectrum of morphologic changes resulting in focal
A.J.C.P. • July 1979
segmental glomerulosclerosis. It is well known that
hematuria and mesangial hypercellularity can occur in
focal segmental glomerulosclerosis, 79 " 17 and although
usually focal, the mesangial hypercellularity is occasionally diffuse. Further support for this approach can
be found in recent reports by Schoeneman and associates14 and Habib.8 In similar studies, these investigators compared the relationship between the clinical
courses of patients with (1) focal segmental glomerulosclerosis with and without mesangial proliferation and
(2) mesangial proliferation with and without focal segmental glomerulosclerosis. The results indicated that
the presence of increased mesangial cellularity was a
more important prognosticator than the presence of
segmental sclerosis. In neither study was hematuria
considered to be particularly important, although most
patients in both series had this sign.
A second possible explanation is that mesangioproliferative nephropathy is a distinct entity of intermediate severity that does not evolve from minimalchange disease or develop into focal glomerulosclerosis. At present, there is little support for this view,
but long-term studies of a closely defined group of patients are necessary to refute it.
A third possibility is that the mesangial-cell proliferation in biopsy specimens from patients with the
nephrotic syndrome identifies a group of individuals
who have a decreased response to steroids, probably
have an increased incidence of renal failure, but may
or may not subsequently have segmental glomerulosclerosis.
The data presented here do not refute any of the
above possibilities. They do indicate that mesangioproliferative nephropathy is an entity with features
sufficiently distinctive to warrant special attention so
that additional patients with longer follow-up studies,
including repeated biopsy, can be identified and studied. Only in this way can the proper place of this clinicopathologic complex in the spectrum of the idiopathic
nephrotic syndrome of children be determined.
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