Recruitment of new osteoblasts and osteoclasts is the earliest critical event in the pathogenesis of human multiple myeloma.

Considering the special relation of human multiple myeloma (MM) to bones, it is of importance to clarify the early steps of bone involvement in this disease. In this work, using bone histomorphometry (including histoenzymologic and kinetic studies for the first time), we have evaluated the bone remodeling (i.e., bone resorption and bone formation rates) of 16 individuals with early MM in comparison with that of 10 with benign monoclonal gammopathy (BMG) and that of 17 patients with previously untreated overt MM. A significantly increased osteoblastic recruitment was observed in the individuals with early MM when compared with those with BMG (P less than 0.01). A significant (P less than 0.01) increased bone resorption (i.e., eroded surfaces, osteoclast numbers and surfaces) was observed from the early stage of MM in comparison with the BMG status where bone resorption remained within the normal range. At the tissue level, there was no difference in terms of bone resorption between early and overt MM. On the other hand, osteoblast activity was significantly reduced in patients with overt MM (P less than 0.05 by comparison with those with early MM). A significant enhancement of osteoblastic recruitment with an increased generation of new osteoclasts is an early critical event in the pathogenesis of human MM. Of particular importance is the early stimulation of osteoblasts, since these cells produce high amounts of IL-6, a potent myeloma cell growth factor and a critical cytokine for the formation of osteoclasts in the bone marrow.

Mechanisms of bone destruction in multiple myeloma: the importance of an unbalanced process in determining the severity of lytic bone disease.

In order to clarify the mechanisms involved in the occurrence of lytic bone lesions (BL) in multiple myeloma (MM), we have compared the presenting myeloma-induced histological bone changes of 14 previously untreated MM patients with lytic BL with those of seven MM patients lacking lytic BL at presentation despite similar myeloma cell mass. A major unbalanced bone remodeling (increased bone resorption with normal to low bone formation) was the characteristic feature of patients presenting lytic BL. Furthermore, this unbalanced process was associated with a significant reduction of bone mass. Unexpectedly, a balanced bone remodeling (increase of both bone resorption and bone formation, without bone mass reduction) rather than a true lack of an excessive bone resorption was the usual feature of patients lacking lytic BL. Our current work clearly shows that a majority (72%) of patients with MM present an important unbalanced bone remodeling at diagnosis, leading to bone mass reduction and bone destruction (unbalanced MM). Some patients (20%) retain a balanced bone remodeling with initial absence of bone destruction (balanced MM). Few (8%) patients have pure osteoblastic MM without bone destruction.

Polyclonal immunoglobulins in malignant plasma cell dyscrasias.

Polyclonal immunoglobulins (Ig) were measured at diagnosis and/or following chemotherapy in 226 patients with a malignant plasma cell dyscrasia (PCD), including 11 patients with solitary myeloma (SM) and 215 patients with multiple myeloma (MM). At diagnosis, Ig synthesis suppression was observed in 80.7% of patients with MM but never in case of SM (p less than 0.001). In patients with MM, there was a clear correlation between IgA or IgM levels (but not IgG) and the total body burden of myeloma cells (p less than 0.01), the lowest levels being observed in patients presenting with the highest myeloma cell mass. Of major interest, for patients evaluated following the induction of chemotherapy, an increase of Ig, from low to normal levels, was only noted in case with a myeloma cell mass regression over 90% and successful achievement of a greater than or equal to 1-year plateau period. We concluded that polyclonal Ig evaluation appeared to be of diagnostic and prognostic values in the management of malignant PCD.

[Primary biliary cirrhosis as seen by the rheumatologist. Apropos of 2 cases]. / La cirrhose biliaire primitive vue par le rhumatologue. A propos de deux observations.

The authors report 2 cases of primary biliary cirrhosis associated with scleroderma (calcinosis, Raynaud's syndrome, sclerodactyly, telangiectasia) in one case, and associated with pseudopolyarthritis in the other; they recall the conditions under which the rheumatologist may be led to make the diagnosis of this disease. Apart from liver diseases including acute or chronic rheumatic signs, one may observe in primary biliary cirrhosis without symptoms certain other rheumatological syndromes: e.g. scleroderma, Sjögren's syndrome, rheumatoid arthritis, Charcot's joint. The laboratory examinations may give unexpected results: e.g. high levels of IgM, the presence of antinuclear antibodies or may give unexpected results: e.g. high levels of IgM, the presence of antinuclear antibodies or cryoglobulins which sometimes orient wrongly the diagnosis in other directions. One may thus note that a high level of alkaline phosphatase should suggest in any case of inflammatory rheumatism, primary biliary cirrhosis, and attempt to prove this by seeking antimitochondrial antibodies.

Importance of quantitative histology of bone changes in monoclonal gammopathy.

Quantitative histology of bone changes, using undecalcified transiliac bone biopsies (UTBB), was performed blindly in 46 individuals with monoclonal gammopathy (MG), including 17 with MG of undetermined significance (MGUS) and 29 with overt multiple myeloma (MM). Three MGUS presented an excess of osteoclastic resorption (OR) in the vicinity of clusters of tumour cells and developed overt B cell malignancies, chronic lymphocytic leukaemia, Waldenström's disease and MM respectively. On the other hand, MGUS with normal OR remained stable (median follow-up = 28 months), with one exception who developed a systemic amyloidosis. In MM, excessive OR was only observed in areas invaded by myeloma cells. OR was frequently normal in active MM lacking myeloma cells in UTBB. Active MM without lesions on radiography had excessive OR. IgA and pure Bence Jones MM appeared more osteoclastic than IgG cases (P less than 0.05). Of major interest was the finding that one third of MM presented histological bone changes similar to osteoporosis, osteosclerosis or osteoblastic metastasis. Two major findings must be emphasized from the current data: UTBB could be of major interest for the early detection of a B cell malignancy; heterogeneity of myeloma bone condition is unexpected. If some changes appear directly related to the tumour (i.e. excessive OR or osteoblastic dysfunction), some others are probably accidentally associated with it (i.e. osteoporosis), both needing treatment other than chemotherapy.

[Contribution of bone biopsy with histomorphometry in the evaluation of monoclonal gammopathy]. / Apport de la biopsie osseuse avec histomorphométrie dans l'évaluation d'une gammapathie monoclonale.

Histomorphometric analysis of bone specimen from the iliac crest was performed to determine total trabecular resorption surface (TTRS) in 46 patients presenting with a monoclonal gammopathy, which was benign in 17 cases and malignant in 29 others. In benign gammopathies, 14 patients had normal TTRS; no adverse progression, representing a malignant B-cell lymphoproliferative disorder occurred after 40 months of follow-up. The three other patients presented increased areas of resorption in contact with lymphoplasmocyte nodules or pure plasmocytes and had an unfavorable course: multiple myeloma, Waldenström's disease, and chronic lymphocytic leukemia. In myeloma, an increase in TTRS was observed when the bone marrow is invaded confirming the dominant local activity of an "osteoclast activating factor". TTRS is all the more extensive according to bone marrow invasion or in IgA or light chain myeloma, all of which are especially destructive of bone. It thus appears that determination of TTRS by bone histomorphometry is of diagnostic importance to recognize the benign or malignant nature of the disorder and has prognostic value in case of multiple myeloma. Bone histomorphometry thus appears as a useful tool in the thorough assessment of monoclonal gammopathies.

Histologic evidence of an abnormal bone remodeling in B-cell malignancies other than multiple myeloma.

In a prospective study of the quantitative bone changes induced by B-cell cancers other than multiple myeloma (MM), but including chronic lymphocytic leukemia (CLL; n = 8), hairy cell leukemia (HCL; n = 3), and Waldenström disease (WD; n = 7), an abnormal bone remodeling close to malignant cells was found in 80% of the patients. This was observed more frequently in cases of diffuse, but not nodular, bone marrow involvement by tumor cells. More particularly, excessive bone resorption (a major feature of MM) associated with a normal to low bone formation (i.e., uncoupling bone disease) was the most frequent feature and in the same range of that observed in overt MM. However, as opposed to MM, this bone resorption was characteristically mediated by small mononucleated osteoclasts (i.e., microresorption). The same phenomena of abnormal bone remodeling, the uncoupling process, excessive bone resorption, and above all microresorption were confirmed by the detailed bone study of five cases of B-cell cancers other than MM presenting lytic bone lesions and hypercalcemia. The current findings are important for clarifying the biology of these B-cell malignant diseases, and also could be of diagnostic and prognostic value.

Osteoblast stimulation in multiple myeloma lacking lytic bone lesions.

The reasons why some patients with multiple myeloma (MM) do not develop severe bone loss, or even develop sclerotic bone lesions, remain unclear. In order to answer this question at the cellular and tissue level, we evaluated the histological bone condition of 10 patients with MM who never developed lytic bone lesions during the course of their disease (including two patients with sclerotic MM). Myeloma-induced bone changes in the close vicinity of myeloma cells were evaluated by quantitative histology (bone histomorphometry). All 10 patients presented a significantly increased osteoblastic activity. This was associated with an increased bone resorption in seven of the 10 cases. Three patients had a pure osteoblastic presentation. These features were the reverse of the pattern observed in seven patients with lytic bone lesions: increased bone resorption with decreased bone formation. Almost all of these 10 patients showing excessive osteoblastic activity had increased serum bone gla protein levels, a specific marker of bone formation. Finally, 90% of these patients were lambda MM (70% of them were IgG lambda MM), an immunoglobulin subtype previously associated with the sclerotic MM variants. In conclusion, a subset of patients with MM never develop severe bone loss because of the stimulation of osteoblastic activity. These patients belong to the same family as osteosclerotic MM, presenting more frequently the IgG type and lambda subtype.