BACKGROUND: Monoclonal gammopathies are common over the age of 50. Patients are usually asymptomatic. However, some patients present with secondary clinical manifestations, which are now grouped under the entity « Monoclonal Gammopathy of Clinical Significance » (MGCS).
METHODS: Here, we report two rare cases of MGCS: an acquired von Willebrand syndrome (AvWS) and an acquired angioedema (AAE).
CONCLUSIONS: The discovery of a decrease in von Willebrand activity (vWF:RCo) or angioedema in a patient over 50 years of age, in the absence of a family history, should prompt a search for a hemopathy and in particular, a monoclonal gammopathy.

POEMS syndrome is a rare form of B-cell dyscrasia with multiple clinical signs including the acronym for polyneuropathy, organomegaly, endocrinopathy, M-protein and skin changes. It is a paraneoplastic syndrome due to an underlying plasma cell disorder belonging to the monoclonal gammopathies of clinical significance (MGCS). The major criteria for this syndrome are polyradiculoneuropathy, clonal plasma cell disorder (PCD), sclerotic bone lesions, elevated vascular endothelial growth factor (VEGF), and the presence of Castleman\'s disease. Minor features include organomegaly, endocrinopathy, skin changes, papilledema, extravascular volume over-load, and thrombocytosis. The diagnosis of POEMS syndrome requires three of the major criteria, two of which must include polyradiculoneuropathy and clonal PCD, and at least one of the minor criteria. VEGF plays a major role in the disease although anti-VEGF treatments have been disappointing. Risk stratification is based on clinical phenotype rather than specific molecular markers. Depending on bone marrow involvement and the number of sclerotic bone lesions, first line therapy should be irradiation or systemic therapy. For patients with a dominant sclerotic plasmacytoma, first line therapy is irradiation. Patients with diffuse sclerotic lesions or disseminated bone marrow involvement and for those who have progression of their disease 3 to 6 months after completing irradiation therapy should receive antiplasma cell systemic therapy, the most effective being high dose chemotherapy with autologous stem cell transplantation. Lenalidomide seems to have a high efficacy with manageable toxicity. Thalidomide and proteasome inhibitors like bortezomib are also effective, but their benefit needs to be weighed against their risk of exacerbating the peripheral neuropathy.

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Serum free light chains (sFLC) assay is an important marker in plasma cell dyscrasia. It is thus recommended for the diagnosis of monoclonal gammopathy, together with serum protein electrophoresis and immunofixation. sFLC assay has also a prognostic value and is a criterion for treatment response and relapse of some monoclonal gammopathies. Three assays are currently available in France, the gold standard being the Freelite® assay, the two others requiring further validation. These three assays are not interchangeable during patient\'s follow-up. The Freelite® assay is integrated in the myeloma diagnostic criteria from the International Myeloma Working Group 2014, and has a higher sensitivity than Bence Jones protein test for diagnosis, treatment response and follow-up of light chain myeloma. The Freelite® assay is the main marker of therapeutic response in light chain amyloidosis and allows to stratify the risk for progression in monoclonal gammopathy of undetermined significance. Some studies have also shown its value in diagnosis of multiple sclerosis and in screening for monoclonal gammopathy in the cases of acute renal failure. The Freelite® assay is then currently essential in myeloma or amyloidosis, and could be soon extended to the management of autoimmune diseases.

Monoclonal gammopathy of renal significance. The term \"monoclonal gammopathy of renal significance\" regroups all renal disorders caused by a monoclonal immunoglobulin (Ig) secreted by a nonmalignant B-cell clone. However, a small clone can synthesize a very toxic protein, producing devastating renal and sometimes systemic damages. The spectrum of renal diseases in MGRS is wide. Renal lesions are classified according to the localization, either glomerular or tubular, and to the pattern of ultrastructural organization of Ig deposits. Physico-chemical characteristics of pathogenic monoclonal Ig are probably involved in their propensity to deposit or precipitate in the kidney, as illustrated by the high rate of recurrence of renal lesions after kidney transplantation if the underlying clone is not suppressed. Early diagnosis and efficient chemotherapy are mandatory to improve renal prognosis and patient survival, particularly in patients with systemic lesions such as AL amyloidosis.
Gammapathies monoclonales de signification rénale. Le terme « gammapathie monoclonale de signification rénale » (MGRS) regroupe l’ensemble des néphropathies liées à la toxicité d’une immunoglobuline monoclonale produite par un clone B indolent, de faible malignité hématologique, mais potentiellement dangereux en raison de la toxicité rénale et parfois systémique de l’immunoglobuline sécrétée. Les lésions rénales des MGRS sont très diverses et classées en fonction du type d’atteinte, glomérulaire ou tubulaire, et du caractère organisé ou non des dépôts ou inclusions d’immunoglobulines monoclonales en microscopie électronique. Les caractéristiques physico-chimiques des immunoglobulines monoclonales jouent probablement un rôle majeur dans l’apparition des lésions comme en atteste la récidive du même type de néphropathie après transplantation rénale si le clone sous-jacent n’est pas contrôlé. Le pronostic rénal, et parfois vital lorsqu’il existe des manifestations systémiques comme au cours de l’amylose AL, dépend de la précocité du diagnostic et de la mise en route d’une chimiothérapie efficace pour contrôler rapidement la production de l’immunoglobuline monoclonale.

BACKGROUND: Impairment of dermal elastic tissue occurs in different entities associated with immunoglobulins or immunoglobulin-derived protein-secreting clonal plasma cell proliferations, such as amyloid elastosis, anetodermic nodular amyloidosis or monoclonal gammopathy-associated cutis laxa. We report a case of cutaneous immunoglobulinemic amyloidosis revealed by a unique chalazodermic presentation and we review elastic tissue impairment in patients with monoclonal gammopathies.
METHODS: A 67-year-old woman consulted for non-infiltrated anetodermic lesions on the upper left quadrant of her abdomen present for ten years. She also had a chalazodermic plaque with abnormal skin wrinkling and laxity in her right axilla. Biopsies revealed deep dermal and subcutaneous amyloid deposits. Immunohistochemistry with lambda light chain was positive. Orcein staining and electron microscopy showed extensive elastolysis. The patient presented no signs of systemic involvement, but a very small amount of monoclonal IgGλ gammopathy was detected during follow-up.
CONCLUSIONS: This is a unique chalazodermic presentation of immunoglobulinemic amyloidosis that does not fit into a clearly-defined nosological setting. It highlights the complex interactions between immunoglobulin-derived proteins, including light and heavy chains, and elastic tissue components, leading to different types of impairment of the latter. We therefore suggest the unifying concept of immunoglobulinemic elastopathy, underscoring the need to screen for monoclonal gammopathy in patients presenting elastic tissue impairments.

BACKGROUND: Acid sphingomyelinase deficiency (ASMD) is an autosomal recessive disease with a clinical spectrum ranging from a neurovisceral infantile form (Niemann-Pick disease type A) to a chronic visceral form also encountered in adults (Niemann-Pick disease type B, NP-B).
METHODS: Retrospective multicentric analysis of French adult patients with ASMD over the period 1985-March 2015. Clinical, biological, and imaging data were analyzed.
RESULTS: Twenty-eight patients (19 males, 9 females) were analyzed. Diagnosis was made before the age of 10 years in 16 cases. Main symptoms at diagnosis were spleen/liver enlargement and interstitial lung disease. Biological abnormalities included: thrombocytopenia (platelet count <150 000/mm3) in 24 cases including 4 patients with platelet count <60 000/mm3, constantly low high-density lipoprotein (HDL) cholesterol, polyclonal hypergammaglobulinemia (n=6), monoclonal gammopathy of unknown significance (n=5), normal prothrombin level discordant with low factor V (n=5), elevated chitotriosidase level (n=11). The diagnosis was confirmed in all cases by deficient acid sphingomyelinase enzyme activity. SMPD1 gene sequencing was performed in 25 cases. The frequent p.R610del mutation was largely predominant, constituting 62% of the non-related alleles. During the follow-up period, three patients died before 50 years of age from cirrhosis, heart failure and lung insufficiency, respectively.
CONCLUSIONS: ASMD in adulthood (NP-B) associates spleen/liver enlargement and interstitial lung disease. Early diagnosis and appropriate management are essential for reducing the risk of complications, improving quality of life, and avoiding inappropriate procedures such as splenectomy. To date, only symptomatic therapy is available. A phase 2/3 therapeutic trial with IV infusion of recombinant enzyme is on-going.

Castleman\'s disease is a lymphoproliferative disorder characterized by angiofollicular lymph node hyperplasia. Recently, a new variant of multicentric Castleman\'s disease has been identified in Japan called TAFRO syndrome. It is characterized by a constellation of symptoms: thrombocytopenia, anasarca, reticulin fibrosis of the bone marrow, renal dysfunction and organomegaly (TAFRO). It is usually associated with polyclonal hyperimmunoglobulinemia. Here, we report the first and unique case of TAFRO syndrome with monoclonal gammapathy.

BACKGROUND: Papular mucinosis is characterised by primary mucin deposition in the dermis. The classification distinguishes between the localised form and the systemic form, which alone can result in complications, but this classification occasionally proves to be inadequate. Herein we report the progression of papular mucinosis, initially atypical due to the absence of cutaneous sclerosis and of misleading granulomatous histological features, which subsequently developed into characteristic scleromyxedema.
METHODS: A 55-year-old male developed a rash comprising countless acral papules. Several biopsies were necessary before a diagnosis of papular mucinosis was made, due to the initial granulomatous appearance at histology. Tests showed monoclonal immunoglobulin of indeterminate significance, but, due to the absence of cutaneous sclerosis, we were able to conclude on typical localised papular mucinosis. Two years later, extensive sclerotic induration of the skin appeared and the diagnosis was modified to one of scleromyxedema. Treatment with intravenous immunoglobulins was given and proved efficacious, but relapse occurred on discontinuation of the therapy.
CONCLUSIONS: Papular mucinosis is a rare disease of unknown physiopathology. The disease classification distinguishes between the localised and systemic forms, but it occasionally proves to be inadequate. Our case suggests a continuum between the localised and systemic forms of the disease. Further, the initial biopsies of acral papules in our patient had a misleading granulomatous appearance, as has been reported numerous times for the systemic forms. This granulomatous histological variant thus appears to constitute a diagnostic criterion for scleromyxedema.

Skin manifestations associated with monoclonal gammapathy are common and can present with various clinical and pathological aspects. They can be the first events leading to the diagnosis of monoclonal gammapathy. They may be present either as specific lesions, including lymphoplasmacytic or pure plasma cell neoplastic infiltrates and monoclonal immunoglobulin deposits, or as non-specific dermatitis, such as leukocytoclastic vasculitis, neutrophilic dermatoses, mucinoses or xanthomatosis, giving little clues for the diagnosis of the underlying disease.