The physiopathological significance of benign monoclonal gammopathy: a study of 64 cases

Crohn's disease and smoldering multiple myeloma: a case report and literature review

Crohn's disease (CD) is a chronic inflammatory bowel disease (IBD) that presents with abdominal pain, weight loss, and diarrhea. Although the etiology has not been fully elucidated, both environmental and genetic causes are known to be involved. In chronic inflammatory conditions such as IBD, B lymphocytes are chronically stimulated, and they induce monoclonal expansion of plasma cells, sometimes resulting in monoclonal gammopathy of undetermined significance. Immunomodulators that are commonly used to control inflammation, such as tumor necrosis factor-α (TNF-α) blockers could increase the possibility of hematologic malignancy. The pathogenesis of multiple myeloma in association with TNF-α inhibitor therapy is attributed to decreased apoptosis of plasma cell populations. Here, we describe a case of a 36-year-old male patient who was diagnosed with immunoglobulin A subtype smoldering multiple myeloma during the treatment for CD with infliximab and adalimumab. We report this case along with a review of the literature on cases of multiple myeloma that occurred in conjunction with CD.

The relationship between hypogammaglobulinemia, monoclonal gammopathy of undetermined significance and humoral immunodeficiency: a case series

Hypogammaglobulinemia of the non-monoclonal immunoglobulin heavy chain classes has been reported in monoclonal gammopathy of undetermined significance (MGUS) patients. Whether low polyclonal immunoglobulin levels are associated with impaired specific antibody production and whether they represent a risk factor for the development of recurrent bacterial infections have not been established in this population. We determined the frequency of MGUS in patients referred to a tertiary care clinical immunology ambulatory care practice for evaluation of hypogammaglobulinemia, who were assessed for deficits in specific antibody production and the presence of recurrent infections. Of the 133 patients evaluated for hypogammaglobulinemia, 68 were screened for monoclonal gammopathy and 5 were found to have MGUS. Three had MGUS associated hypogammaglobulinemia in the absence of a defining primary immunodeficiency, one possibly had common variable immunodeficiency, and one had an uncertain diagnosis. Thus, MGUS may be uncovered in patients presenting with hypogammaglobulinemia even in those who lack an elevated serum level of IgG, IgM, or IgA.

Review article: multiple myeloma and inflammatory bowel disease

Since 1964 only nine cases of multiple myeloma occurring in the setting of inflammatory bowel disease have been reported. Although this occurrence may be a mere unfortunate coincidence, there are sound pathophysiological reasons for such an event. The possibility that chronic inflammatory conditions, immunomodulator therapy, and infliximab can predispose to multiple myeloma and lymphoma is reviewed. We discuss in detail the only reported case of multiple myeloma arising in the setting of infliximab treatment for Crohn's disease. It is highly probable that infliximab therapy had a causal role in our patient developing multiple myeloma. The pathogenesis of multiple myeloma arising in the setting of infliximab therapy may be related to decreased apoptosis of plasma cell populations. Since it is possible that a causal association exists between infliximab therapy and multiple myeloma, additional screening measures may be required in patients with Crohn's disease on infliximab.

Monoclonal gammopathies of undetermined significance: a review

Monoclonal gammopathy of undetermined significance (MGUS) denotes the presence of a monoclonal protein (M-protein) in patients without evidence of multiple myeloma (MM), macroglobulinemia, amyloidosis (AL), or a related plasma cell proliferative disorder. MGUS is found in approximately 3% of persons older than 70 years and in about 1% of those older than 50 years. In a series of 1384 patients from south-eastern Minnesota in whom MGUS was diagnosed at Mayo Clinic from 1960 through 1994, the risk of progression was 1% per year. Patients were at risk of progression even after 25 years or more of a stable monoclonal gammopathy. The risk of development of MM was increased by 25-fold, the risk of macroglobulinemia was 46-fold, and the risk of primary AL was 8.4-fold when compared with a similar population (Surveillance, Epidemiology and End Results). The concentration of the serum M-protein was the major independent predictor of progression. Patients with an immunoglobulin M (IgM) or an IgA monoclonal gammopathy had a higher risk of progression than those with an IgG monoclonal gammopathy. The presence of a urine M-protein or the reduction of one or more uninvolved Igs was not a risk factor for progression. MGUS may be associated with many different disorders, including lymphoproliferative diseases, leukemia, connective tissue disorders, dermatologic diseases, and neurologic disorders.

Prognostic factors for malignant transformation in monoclonal gammopathy of undetermined significance and smoldering multiple myeloma

PURPOSE

To evaluate the natural history of monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM), identify early predictors of evolution, and assess whether associated conditions correlate with disease progression.

PATIENTS AND METHODS

A total of 1,231 consecutive patients with either MGUS (n = 1,104) or SMM (n = 127) diagnosed from July 1975 to March 1998 were included in the study. Cumulative survival probability and cumulative probability of transformation into lymphoproliferative disease were calculated by means of the Kaplan-Meier estimator. Univariate and multivariate Cox models were used to identify possible predictors of malignant evolution.

RESULTS

Cumulative transformation probability at 10 and 15 years was 14% and 30%, respectively. At a median follow-up of 65 months (range, 12 to 239 months), 64 MGUS cases (5.8%) evolved to multiple myeloma (MM) (n = 43), extramedullary plasmacytoma (n = 1), primary amyloidosis (n = 1), Waldenström's macroglobulinemia (n = 12), non-Hodgkin's lymphoma (n = 6), and B-chronic lymphocytic leukemia (n = 1). At a median follow-up of 72 months (range, 12 to 247 months), 25 SMMs (19.7%) evolved to overt MM. A lower evolution risk was observed in MGUS than in SMM (P <.0001). Greater than 5% marrow plasmacytosis, detectable Bence Jones proteinuria, polyclonal serum immunoglobulin reduction, and high erythrocyte sedimentation rate (ESR) were independent factors influencing MGUS transformation. SMM progression correlated with greater than 10% marrow plasma cells, detectable Bence Jones proteinuria, and immunoglobulin (Ig) A isotype. Neither concomitant diseases nor immunosuppression correlated with progression.

CONCLUSION

Careful evaluation of marrow plasmacytosis, urinary paraprotein, background immunoglobulins, ESR, and paraprotein isotype might help identify at presentation patients with benign monoclonal gammopathies requiring stricter monitoring.

Monoclonal gammopathies of undetermined significance

Monoclonal gammopathy of undetermined significance is characterized by a serum M-protein level less than 3 g/dL, fewer than 10% plasma cells in the bone marrow, and no or only small amounts of M-protein in the urine; by the absence of lytic lesions, anemia, hypercalcemia, and renal insufficiency; and most importantly, by the stability of the M-protein and by the failure of other abnormalities to develop. Monoclonal gammopathy of undetermined significance is found in approximately 3% of persons older than 70 years and in 1% of those older than 50 years. Approximately one fourth of patients develop MM, AL, WM, or a similar malignant lymphoproliferative disorder during long-term follow-up. In a series of 241 patients at the Mayo Clinic, the actuarial rate of development of serious disease was 16% at 10 years and 40% at 25 years. The median interval from recognition of the M-protein to the diagnosis of MM was 10 years (range, 2-29 years). The plasma cell labeling index and the presence of circulating plasma cells in the peripheral blood suggest active disease. There are no findings at the time of recognition of MGUS that distinguish patients who will remain stable from those in whom a malignant plasma cell proliferative disorder will develop. Therefore, one must perform serial measurements of the M-protein and periodically evaluate the clinical and laboratory features.

["Benign" monoclonal gammopathy and chronic lymphatic leukemia in a patient with Noonan syndrome]

HISTORY

At the age of 32 a "benign" monoclonal gammopathy of lightchain kappa with Bence Jones protein is diagnosed in a man born 1934. In addition a Noonan-syndrome is found.

COURSE

Twenty-four years later he gradually develops a chronic lymphatic leukaemia (B-CLL) which up to now does not need treatment (October 1996). The neoplastic B-cells exprime monoclonal lightchain lambda on the cellmembrane and in the cytoplasma undetectable by immunefixation in the serum. Irrespective of that the known monoclonal gammopathy exprimes IgG-kappa without an increase in the number of plasmacells in the bonemarrow.

CONCLUSION

There are hints that the congenital Noonan-syndrome can be associated with B-cell disorders.

Qualitative immunoglobulin abnormalities in HIV-positive patients: long-term follow-up

We studied the immunoglobulins of a cohort of 212 HIV-positive patients followed-up for 13 years. The qualitative study of immunoglobulins by immunoelectrophoresis and immunofixation distinguished three groups of patients: those with monoclonal immunoglobulins, those with minor abnormalities of immunoglobulins and those with polyclonal immunoglobulins. We characterized these groups according to age, sex, immunoglobulin isotypes, and survival curves. The results show that this population of immunoglobulinopathies has distinctive characteristics. In particular, the presence of immunoglobulin abnormalities has no significant prognostic value.

Monoclonal gammopathy of undetermined significance and solitary plasmacytoma. Implications for progression to overt multiple myeloma

MGUS is characterized by the presence of a serum M-protein less than 3 g/dL; fewer than 10% plasma cells in the bone marrow; no, or only small amounts of, M-protein in the urine; absence of lytic lesions, anemia, hypercalcemia, and renal insufficiency; and, most importantly, stability of the M-protein and failure of development of other abnormalities, MGUS is found in approximately 3% of persons older than 70 years and in 1% of those 50 years or older. During long-term follow-up, approximately one fourth of patients develop multiple myeloma (MM), amyloidosis, macroglobulinemia, or a similar malignant lymphoproliferative disorder. Actuarial rate of development of serious disease was 16% at 10 years, 33% at 20 years, and 40% at 25 years in our experience. The interval from recognition of the M-protein to the diagnosis of MM ranged from 2 to 29 years (median, 10 years). The size of the M-protein, hemoglobin value, percentage of bone marrow plasma cells, amount of light-chain excretion, presence of hypercalcemia or renal insufficiency, and presence of lytic bone lesions are often helpful in differentiating MGUS from MM and macroglobulinemia. The plasma cell labeling index and the presence of circulating plasma cells in the peripheral blood are indicators of active disease; however, there are no findings at the diagnosis of MGUS that reliably distinguish patients who will remain stable from those in whom a malignant condition will develop. Thus, a physician must perform serial measurements of the M-protein in the serum and periodic evaluation of the pertinent clinical and laboratory features to determine whether MM, macroglobulinemia, systemic amyloidosis, or related disorders have developed. Solitary plasmacytoma is characterized by the presence of a tumor consisting of monoclonal plasma cells identical to those in MM. In addition, skeletal roentgenograms must show no lytic lesions, a bone marrow aspirate must contain no evidence of MM, and immunoelectrophoresis or immunofixation of the serum and concentrated urine should show no M-protein. Exceptions to the presence of an M-protein occur, but therapy of the solitary lesion often results in disappearance of the M-protein. Tumoricidal irradiation (4000 to 5000 cGy) for approximately 4 weeks is the treatment of choice. Overt MM occurs in approximately 50% of patients with solitary plasmacytoma. Progression occurs in most patients within 3 years. The three patterns of failure are (1) development of MM, (2) local recurrence, and (3) development of new bone lesions in the absence of MM.

Risk of malignant transformation in patients with monoclonal gammopathy of undetermined significance

The acturial probability of malignant transformation was analyzed in a series of 263 patients with monoclonal gammopathy of undetermined significance (MGUS) over a 15-year period and followed from 5 to 20 years. At a median follow-up of 11.5 years, 157 patients (59.7%) had died of causes unrelated to MGUS, 47 (17.9%) were still alive and presented no increase in monoclonal component, 11 (4.1%) presented an increase in monoclonal component without evidence of malignant immunoproliferative disease, and 48 (18.3%) had developed a malignant transformation of MGUS. In particular, MGUS evolved into 35 cases of multiple myeloma, two of solitary plasmacytoma of the bone, four of macroglobulinemia, three of malignant lymphoma, two of amyloidosis, one of chronic lymphocytic leukemia, and one of plasma cell leukemia. The cumulative incidence of malignant transformation was 18.3%; and the actuarial risk of malignant transformation was 6.1, 15.4, and 31.3% at 5, 10 and 20 years, respectively. The multivariate regression analysis according to Cox's proportional hazard model selected among 22 different variables established at initial diagnosis of MGUS only age as the factor significantly (P < 0.011) and negatively (b = -1.104) related to the risk of developing a malignant immunoproliferative disease. Therefore, patients with MGUS present an increased risk of developing a malignant lymphoproliferative or plasma cell proliferative disease, and MGUS could be considered a pre-neoplastic condition. Since no clinical or laboratory features are able to identify in advance the patients at high risk of disease progression, each patient must be followed up periodically and over an indefinite period.

[Monoclonal gammopathies of undetermined significance in the elderly: apropos of 80 cases]

The authors reviewed the medical records of 80 patients with monoclonal gammopathy of undetermined significance who were examined at the hospital of Dijon between July 1990 and December 1992. The study included 43 males and 37 females with a mean age of 81.0 +/- 5.5 years. Type of M-component was IgG in 65% of the cases, IgA in 19% and IgM in 13.5%. A biclonal gammopathy was found in 2.5% of the cases. The follow-up duration was 24.6 +/- 10.8 months (range: 1-42 months). The survival probability of patients with monoclonal gammopathy of undetermined significance was 66.6% at 36 months compared with 75.6% in a control population. Lymphoplasmacytic disease developed in four patients (5%). There is a dramatic increase in monoclonal gammopathy with increasing age and the risk of malignant transformation must be continued whatever the age of patients. Further studies are required to determine routine follow-up in the elderly patient with monoclonal gammopathy of undetermined significance until the long term utility and cost/benefit ratio of screening techniques are known.

Malignant transformation and life expectancy in monoclonal gammopathy of undetermined significance

The actuarial probability of malignant transformation and the impact on expected survival were analysed in a series of 128 persons diagnosed with monoclonal gammopathy of undetermined significance (MGUS) over a 20-year period. At a median follow-up of 56 months the M-component remains stable in 101 patients (78.9%), 14 patients (10.9%) have died from non-related disorders and 13 (10.2%) have developed malignant transformation of MGUS (multiple myeloma, 10; primary amyloidosis, two; Waldenström's macroglobulinaemia, one). The actuarial probability of malignant transformation at 5 and 10 years was 8.5% and 19.2%, respectively. When different presenting features were analysed for predictive value of the malignant transformation, the IgA type of MGUS was the only variable associated with a higher probability of such an event (P less than 0.025). Although no significant difference was observed between the survival probability of persons with MGUS and that of the control population, the development of malignant transformation was associated with a shorter survival (P less than 0.001).

Immunoglobulin D benign monoclonal gammopathy. A case report

The authors report a case, perhaps the first, of immunoglobulin D (IgD) benign monoclonal gammopathy. The patient, a 48-year-old black woman, initially had a 500 mg/dl IgD-lambda M-spike, hypercalcemia, and anemia. There was no bone pain, lytic bone lesions, or evidence of renal failure. The bone marrow showed 2.8% plasma cells with a diffuse (not nodular) IgD plasmacytosis and strong lambda predominance. Only trace amounts of free lambda light chains could be demonstrated by immunoelectrophoresis in serum and concentrated urine. The anemia responded quickly to iron therapy. Chemotherapy was not initiated. Over the 6+ years of follow-up, the patient has had no progression of clinical disease attributable to her IgD monoclonal gammopathy. The IgD M-spike has steadily decreased.

Lymphoid aggregates in bone marrow: study of eventual outcome

The practical importance of finding a morphologically benign lymphoid aggregate in the bone marrow of patients without known lymphoproliferative disease was assessed in 786 consecutive patients who had had 951 iliac crest bone marrow biopsies performed. Of these, 430 patients known to have lymphoproliferative disease at the time of biopsy were excluded. Of 356 patients, 86 (aggregate group) had at least one lymphoid aggregate in their biopsy specimen biopsy specimen (82 morphologically benign, three suspicious, and one malignant). Another 86 patients without aggregates (control group) were matched by age and sex. Both groups were followed up until death, or for a mean of 21.9 and 22.9 months, respectively, to assess their outcome. Eighteen (22%) of the 82 patients with morphologically benign lymphoid aggregates were later proved to have lymphoproliferative disease compared with none of the 86 control patients. Another 12 patients in the aggregate group and seven in the control group were suspected of having a lymphoproliferative disease on clinical grounds, so that altogether 30 (37%) and seven (8%), respectively, developed confirmed or suspected lymphoproliferative disease. In both cases the differences were highly significant (p less than 0.001). It is suggested that lymphoid aggregates in clinical biopsy material may not be a physiological finding and should alert pathologists or haematologists to the possibility of lymphoproliferative disease.

Laboratory investigation of monoclonal gammopathy during 10 years of screening in a general hospital

Protein electrophoresis was carried out on 102,000 samples from the patients of a district general hospital over 10 years, and a monoclonal protein was detected in 730 cases; of these, 114 could be classified as B cell malignancies and 261 as monoclonal gammopathy of undefined significance (MGUS). The various clinical and laboratory features of monoclonal gammopathy were examined with respect to distinguishing the malignant conditions from MGUS at first presentation.

Diagnostic value of the concentration of M-component in initial classification of monoclonal gammopathy

The diagnostic value of the concentration of a serum M-component in initial classification of monoclonal gammopathy into malignant monoclonal gammopathy (MMG) and monoclonal gammopathy of undetermined significance (MGUS) was evaluated in 315 consecutive individuals with IgG, IgA or IgM type M-components. The final diagnosis was MMG in 84 and MGUS in 231 patients. Serum concentration was significantly highest in MMG, but for all 3 kinds of M-components, overlapping serum concentrations between MMG and MGUS were found. Highest efficiency was reached with a serum concentration of 30.2 g/l for IgG, 26.6 g/l for IgA and 22.7 g/l for IgM. Using these values, an initial correct classification was achieved in 0.90 of IgG M-components, in 0.91 of IgA M-components and in 0.79 of IgM M-components. Normal levels of uninvolved immunoglobulins were found to point strongly to MGUS.

Monoclonal gammopathy in general practice. Diagnostic value of typing and quantitation of immunoglobulins

The diagnostic value of typing and quantitation of immunoglobulins were investigated in 88 persons with monoclonal gammopathy diagnosed in general practice. Of the 88 persons, 13 had malignant monoclonal gammopathy (MMG) and 75 monoclonal gammopathy of undetermined significance (MGUS). IgG was the immunoglobulin most often associated with a benign disorder. The higher the concentration of M-component was, the higher too was the frequency of MMG. All 40 persons with normal levels of immunoglobulins had MGUS. Suppression of immunoglobulins other than the M-component was found in 69% with MMG and 20% with MGUS. The combination of an elevated level of monoclonal immunoglobulin and suppression of other immunoglobulins was seen in 69% with MMG, but in only 12% with MGUS. The results from typing and quantitating may serve to indicate whether further investigations are justified in patients not suspected of MMG, but in whom a M-component is found.

Chylomicronaemia in multiple myeloma

A patient with multiple myeloma presented with an accumulation of chylomicron-like particles. This rare finding resembled that of the type V hyperlipoproteinaemia phenotype. The lipid and lipoprotein concentration and composition were compared with values obtained from other patients with multiple myeloma, patients with the type V hyperlipoproteinaemia phenotype (accumulation of chylomicrons and very low density lipoproteins), and normal subjects. An immunoglobulin-lipid complex was demonstrated in our patient. This complex was found not to be associated with the chylomicrons and was detected only in the lipoprotein-deficient plasma. Lipid and lipoprotein concentration and composition differed from the other groups. Very low density lipoprotein concentration was reduced, and there was thus a marked difference from the type V phenotype. The chylomicrons derived from this patient were also richer in apolipoprotein C compared to chylomicrons derived from the patients with type V hypolipoproteinaemia. It appears that the abnormal composition of the triglyceride-rich lipoproteins observed in this patient renders her refractory to the normal pathways of metabolism.

Plasma cholesterol concentration and extra lipid band in monoclonal gammopathies

Plasma lipids and lipoproteins were studied in 21 patients with benign monoclonal gammopathy, 21 patients with multiple myeloma and seven patients with Waldenström's macroglobulinaemia. Results were compared with those of a control group, age and sex matched. Low plasma cholesterol levels in all three patient groups were associated with low HDL-cholesterol concentrations. Apo A-I, but not apo B, was significantly reduced. Sixty per cent of the patients exhibited an extra lipid band on plasma lipoprotein electrophoresis, which could be an immunoglobulin-lipid complex. In these patients plasma and LDL-cholesterol levels were significantly lower than in those patients in whom this band was absent. No correlation was found between the severity of the disease and plasma lipid pattern.

Bone marrow histology in Waldenström's macroglobulinaemia. Clinical relevance of subtype recognition

Bone marrow biopsies of 137 patients with Waldenström's macroglobulinaemia (WM), 26 with non-secretory immunocytoma and 32 with benign monoclonal gammopathy were processed for histologic evaluation. Bone marrow involvement was found in 110 (80%) initially, and in 24 (18%) in sequential biopsies. 3 types were distinguished: lymphoplasmacytoid (47%), lymphoplasmacytic (42%) and polymorphous (11%) with median survivals of 74, 25 and 12 months, respectively. When grouped according to the tumour cell mass in the biopsies, the median survivals were 55, 21 and 8 months for less than 20 vol%, 20-50 vol% and greater than 50 vol% respectively; in each subtype, the tumour cell mass correlated with the disease progression. 6 clinical variables were also found prognostically significant. These results demonstrate that (i) 98% of patients with WM have bone marrow involvement; (ii) the lymph node sub-classification is applicable to the bone marrow and has both clinical and prognostic significance; (iii) patients may be staged according to the tumour cell burden in the bone marrow biopsy.

Lymphocyte subpopulations in benign monoclonal gammopathy

Peripheral blood samples from normal individuals and from patients with benign monoclonal gammopathy or multiple myeloma were separated and assayed by immunofluorescence and rosette formation for T, B, TG and TM subpopulations. When compared with normal individuals and multiple myeloma patients, the benign monoclonal gammopathy patients could be divided into 2 groups. The 1st group demonstrated a T/B ratio similar to normal individuals, whereas in the 2nd group the ratio resembled that of the myeloma patients, with a decrease in the fraction of T lymphocytes, accompanied by an increased number of B lymphocytes. An analysis of the monoclonal Ig fraction levels indicated that the 2 groups differ in this respect as well. In the 1st group, the level of the monoclonal immunoglobulin was stable, with small fluctuations. The 2nd group demonstrated a general increasing M-component, especially in the 4-6 months preceding the study. The 2 benign monoclonal gammopathy groups exhibited a trend to a lower TM/TG ratio compared to normals; this change is more prominent in the 2nd group. Analysis of the T lymphocyte subpopulations indicated an overall decrease in the fraction of TM multiple myeloma. The above-mentioned parameters might thus aid in discriminating among BMG patients with regard to their tendency towards a malignant transformation.

Polyneuropathy and benign monoclonal gammopathy

Recently the rather frequent occurrence of benign monoclonal gammopathy (BMG) has been reported in peripheral neuropathy. Sometimes this syndrome is part of a multisystemic disorder in which organomegaly, endocrine disturbances, skin changes and focal bone lesions may also occur. The clinical picture and the cerebro-spinal fluid findings resemble the chronic relapsing Guillain-Barré syndrome. The polyneuropathy seems to be of the primarily demyelinating type. The pathogenetic relationship with the gammopathy is as yet not clear, but treatment of the plasma cell dyscrasia has a favourable effect on the polyneuropathy. We report our experiences with 5 patients with polyneuropathy and BMG and compare our clinical, laboratory and histological data with the literature.

Bone biopsy in haematological disorders

Bone marrow biopsies are now widely used in the investigation and follow-up of many diseases. Semi-thin sections of 8216 undecalcified biopsies of patients with haematological disorders were studied. Observations were made on the cytopenias and the myelodysplastic syndromes, the acute leukaemias the myeloproliferative disorders, Hodgkin's disease and the malignant lymphomas including multiple myeloma, hairy cell leukaemia and angioimmunoblastic lymphadenopathy. Bone marrow biopsies are essential for the differential diagnosis of most cytopenias and for the early recognition of fibrosis which most frequently occurred as a consequence of megakaryocytic proliferation in the myeloproliferative disorders. Different patterns of bone marrow involvement were found in the lymphoproliferative disorders and both their type and extent constituted factors of prognostic significance. A survey of the literature is given and the conclusion is drawn that bone marrow biopsies provide indispensible information for the diagnostic evaluation and the follow-up of patients with haematological disorders.

Spontaneous immunoglobulin changes in human plasma-cell dyscrasia

A series of spontaneous changes affecting the nature of the immunoglobulin secretion of plasma cels is described in a patient initially diagnosed as IgG lambda benign monoclonal gammopathy. After several years a slight increase in the amount of serum monoclonal immunoglobulin occurred; shortly thereafter an aggressive form of multiple myeloma was diagnosed. Unexpectedly a rapid spontaneous decrease of the monoclonal immunoglobulin, accompanied by the appearance in the serum of increasing quantities of a complex containing intact lambda light chains, then occurred. Concomitantly a fragment of the corresponding free light chain was was detected in the urine. A parallel is drawn between the facts observed in this patient and in an animal model recently proposed to explain the different types of structural immunoglobulin abnormalities in multiple myeloma.