is defined as having a monoclonal protein
in a small but abnormal
concentration( <3g/dl). But the bone marrow doesn’t meet criteria for plasma
cell percentage that qualifies for myeloma.
The incidence of MGUS
is around 3.2% especially in the age >50
and the incidence rises as you
age. Given the number of renal transplants are increasing especially in the age
>50, it is evident that this entity comes up now frequently at transplant
selection meetings. What do we do? Is it
a risk factor? Should we be worried?
gammopathy of renal significance) is a term now used to describe entities that
have renal damage from MGUS. A recent KI paper sheds more light on the
pathology of such cases. High rates of recurrence and the recurrence is early
and more severe than in the native kidney. ( 40-60%) if MGUS had presented
as MGRS( or some folks might want to call is MGKS). Risk is especially high when there is a
circulating Monoclonal immunoglobulins still around. Recurrence is early and much more severe than
the native disease.
Soltero et al.
transplant candidates with MGUS between 2000 and 2007 in a single center
study. MGUS that received a KT were
compared with MGUS that were not transplanted.( similar age and CV risks) . Of
1215 KT candidates, 34 were found to have MGUS
(11%). The gammopathy was
monoclonal in 76% of the cases. Nine patients with MGUS were transplanted. Following
transplantation, the MGUS group had a lower survival than the non-transplanted
group. (p = 0.0008).
Follow-up of 18.7 ± 15.4 months, seven patients (78%) died.
Causes of death were cerebral abscess, lung cancer, sepsis, melanoma, bacterial
meningitis, myocardial infarction. They had requested UNOS database from
1987-2003 and only found two reported cases of MGUS to UNOS. Hence data might not be possible to be
obtained from UNOS as not many centers are asking this information.
There are cases of LCDD
and proliferative GN
monoclonal deposits recurring after transplant. Most of the cases had untreated
monoclonal clones prior to transplantation. They would now be classified as
Is MGUS a risk factor for
development of MM post transplantation?
A study from Mayo
had indentified patients who had MGUS either before or after
transplant. Of the 3518 patients who underwent transplantation, MGUS was found
in 42 patients( 23 pre and 19 post).
They were followed for 8 years.
17% of pre transplant MGUS patients developed malignancies such as
smoldering myeloma and other hematologic cancers. None of the patients who developed MGUS post
transplant progressed to MM.
Another more recent study
by the Mayo group
looked at newly diagnosed MM cases post transplantation.
7 cases were identified and 4 of them had MGUS pre transplant and two of them
had clonal plasma cells in bone marrow. They concluded that MGUS prior to
transplant was a risk factor for MM post transplant.
Garcia et al
recently that MGUS following transplantation is a different phenomenon. It
was >100 times more frequent in
transplant patients than in general population. Of their small subset of 11
patients with post transplant MGUS, only one developed PTLD. In contrast to MGUS in general population, progression to plasma
cell dyscrasias was absent and it’s incidence is unknown A longitudinal study
patients demonstrated that most of the MG reflected transient B-cell monoclonal
proliferations, probably due to an immunodeficiency. Usually associated with
intense immunosuppression and M protein is usually small and multiple bands.
In summary, MGRS may not be a contraindication
to kidney transplantation as risk of dying from their clone is low. No data to suggest that small B-cell clones
are truly curable but there might be a high rate of recurrence in certain
types. While LCDD and amyloidosis might have a slower recurrence rate,
proliferative GN with monoclonal deposits might be must faster. MGUS might be a
risk factor for development of active hematologic disease post kidney
transplant. The decision to transplant
might depend on considering the underlying MGRS characteristics, initial
therapeutic response, extrarenal manifestations, and the patient’s status. Risk
of graft loss, its link with the B-cell clone and the potential need for
reintroduction of chemotherapy should be explained to the recipient and the
The field is still unsure on the