Clinical Reasoning: A 49-Year-Old Man With Progressive Numbness, Gait Instability, and Tremors.

Approaching patients with paraproteinemic neuropathies can be challenging for the practicing neurologist, and a well-defined strategy considering specific etiologies is necessary to arrive at the correct diagnosis. In this case, a 49-year-old man presented with a 2-year history of progressive upper then lower extremity numbness, weakness, gait instability, and tremors. His examination was marked by proximal and distal symmetric upper and lower extremity weakness, large more than small-fiber sensory loss, prominent sensory ataxia, action and postural tremors, and globally absent deep tendon reflexes. His workup was notable for a chronic demyelinating sensorimotor polyradiculoneuropathy and a monoclonal immunoglobulin (Ig) M kappa gammopathy. This case highlights the approach to a patient with a rare subtype of IgM paraproteinemic neuropathy with a review of the differential diagnoses, red flag features of co-occurring hematologic disorders, and guided workup. We further discuss typical features of this rare diagnosis and therapeutic options.

Serum-free light chains in the evaluation of M-component disease.

Current guidelines recommend screening with serum M-protein and serum-free light chain analysis (S-FLC) when an M-protein-related disorder is suspected. Many patients with multiple myeloma will be overlooked if only serum M-protein is measured. Despite this, the general practitioners in some areas of Denmark cannot order S-FLC. This review aims to disseminate knowledge of the S-FLC analysis, its applicability, and limitations in the diagnostic workup for suspected monoclonal gammopathies.

Clinical significance of FLC tests in patients without other evidence of hematologic disorder.

The clinical significance of an abnormal free light chain (FLC) test, performed due to unspecific complains in the absence of a known plasma cell dyscrasia (PCD) or lymphoproliferative disease (LPD), is not fully elucidated. We investigated the importance of an abnormal FLC ratio (FLC-R) in this setting. Patients registered in the Maccabi Healthcare Services database, tested for FLC during 2007-2023 without previously documented PCD/LPD or increased total protein (TP) level, were reviewed. Demographics, co-morbidities, and laboratory tests were recorded. FLC-R was defined as normal (0.26-1.65) or slightly (slAb 0.1-0.26/1.65-4), moderately (mAbn 0.1-0.05/4-8) and significantly abnormal (sigAb- < 0.05 or > 8). Factors associated with PCD/LPD and overall survival were identified. In total, 8,661 patients, 2,215 (25.6%) with abnormal FLC-R [2,090 (24.1%)-slAb, 65 (0.75%)-mAbn and 60 (0.7%)-sigAb], were analyzed. Almost none had anemia nor acute renal failure. 14% had concomitant increased immunoglobulins. Within a median follow-up of 52 months, 943 were diagnosed with PCD (816-MGUS, 127-MM/Amyloidosis/plasmacytoma) and 48 with LPD. Median time to PCD and LPD were 19 and 28 months. Multivariate analysis found slAb (HR = 1.8, CI95%:1.53-2.12, p < 0.001), mAbn (HR = 6.3, CI95%:4.16-9.53, p < 0.001), and sigAb FLC (HR = 10.4, CI95%:7.0-15.35, p < 0.001), to be associated with PCD/LPD diagnosis. Decreased IgG, increased IgA, and concomitant comorbidities predicted PCD, whereas increased IgM predicted LPD. Older age, male gender, anemia, decreased albumin, increased IgG and concomitant comorbidities, predicted shorter survival. Our large study emphasizes the independent clinical significance of abnormal FLC-R as a predictor of PCD/LPD diagnosis even in patients with normal TP level, promoting early detection of PCD/LPD.

TEMPI syndrome: difficult to diagnose, "easy" to treat?

TEMPI syndrome is a rare, acquired disorder with multisystemic manifestations. It is classified as a plasma cell disorder and is characterized by telangiectasias, erythrocytosis, monoclonal gammopathy, perinephric fluid collections and intrapulmonary shunt. Even though TEMPI's pathophysiology remains elusive, it responds to anti-myeloma therapy indicating that the monoclonal protein or clone plays a key role. We present a challenging case of a 73-year-old man with erythrocytosis and deteriorating renal function with nephrotic-range proteinuria in whom after extensive work up, the diagnosis of TEMPI syndrome was made. He was received treatment with daratumumab-bortezomib-cyclophosphamide and dexamethasone (Dara-VCD) and achieved a hematological and clinical response. We also report preliminary data on a multiplex assay for cytokines and growth factors for two patients with TEMPI syndrome and note lower levels for non-specific innate immunity related cytokines. A direct link between renal impairment and TEMPI syndrome is not currently established; cytokine deregulation could potentially be involved in the ischemic changes observed in the renal biopsy of our patient.

Elevated polyclonal IgG4 mimicking a monoclonal gammopathy in IgG4-related disease-a case-based review.

IgG4-related diseases (IgG-RDs) are a group of fibroinflammatory diseases that affect a variety of tissues, resulting in tumour-like effects and/or organ dysfunction. Monoclonal gammopathies (MGPs) are a group of disorders characterized by clonal proliferation of plasma cells or lymphoid cells resulting in the secretion of a monoclonal immunoglobulin. Cases of MGPs in IgG4-RDs coexisting with plasma cell dyscrasias and lymphoid neoplasms have been reported over the past few years. Therefore, the results of examinations of M protein in IgG4-RD patients should be interpreted with caution. Herein, we report the case of a 58-year-old male with a history of type 2 diabetes who presented with submandibular masses, anosmia, swollen lymph nodes, proteinuria, and renal impairment. Laboratory tests revealed hyperglobulinemia and elevated levels of IgG4 (124 g/L) and serum-free light chains (sFLCs). Serum protein electrophoresis (SPEP) revealed an M spike of 5.6 g/dL, and immunofixation electrophoresis (IPE) revealed biclonal IgG-κ and IgG-λ. The patient underwent bone marrow, lymph node, and kidney biopsy, which ruled out plasma cell disorders and lymphoma. He was finally diagnosed with an IgG4-RD comorbid with diabetic nephropathy. The findings in this case highlight that significant activation of B cells in IgG4-RD patients, especially those with multiorgan involvement can lead to significant hyperglobulinemia and high sFLC and IgG4 levels, which are more pronounced in the setting of renal impairment. Relatively high concentrations of polyclonal IgG4 can give rise to a focal band bridging the ß and γ fractions, which may mimic the appearance of a monoclonal band on SPEP and monoclonal gammaglobulinemia in IFE. The patient experienced considerable improvement in his symptoms after rituximab combined with glucocorticoid therapy, and a monoclonal immunoglobulin was not detected.

Renal impairment in monoclonal gammopathies and multiple myeloma.

The incidence of monoclonal gammopathy (MG) increases with age. In individuals over 80 years of age, we can diagnose the presence of monoclonal immunoglobulin (MIg) in up to 10 % of cases. Not only malignant diseases such as multiple myeloma (MM), but also benign forms such as MGUS (monoclonal gammopathy of undetermined significance) can lead to renal involvement. The light chains of immunoglobulins (LC) are the most damaging to the kidneys, as they are freely filtered into the urine due to their molecular weight. Detection of MIg relies mainly on a combination of immunofixation electrophoresis of serum (IELFO) and urine and determination of free light chains (FLC) of kappa and lambda and their ratio (κ/λ) in serum. The combination of these tests will detect the presence of MIg with 99 % sensitivity. Renal damage in MG may be caused by direct deposition of MIg in the glomeruli (e.g. AL amyloidosis, LC deposition disease) or tubules (in the distal tubule as a myeloma kidney or in the proximal tubule as Fanconi syndrome or proximal tubulopathy). Typical urinary findings in these diseases are moderate or severe proteinuria or nephrotic syndrome. Acute kidney injury (AKI) can be expected especially when serum FLC is >500 mg/l. Renal biopsy is crucial to establish an accurate diagnosis and thus initiate the correct treatment. Treatment of these types of renal damage involves the same treatment regimens used in the treatment of MM, including proteasome inhibitors or daratumumab.

[Chinese expert consensus on the application of flow cytometry for the detectin of circulating plasma cells in plasma cell disorders (2024)].

Flow cytometry plays an important role in the diagnosis and treatment of plasma cell diseases, particularly in the detection of circulating plasma cells (CPCs) in the peripheral blood. A consensus about the normalized use of flow cytometry in detection of CPCs in peripheral blood in clinical practice has been achieved. This consensus is founded on evidence-based principles, which elucidates the timing and value of flow cytometry for the detection of CPCs in the monoclonal gammopathy of undetermined significance, smoldering myeloma, multiple myeloma, and plasma cell leukemia and standardizes flow cytometry in the detection of CPCs in plasma cell diseases.

Paraprotein-Mediated Glomerular Diseases.

Paraproteinemias are a group of complex diseases associated with an overproduction of a monoclonal immunoglobulin that can cause a diversity of kidney disorders and end-organ damage. In this review, we focus on paraprotein-mediated glomerular diseases. Kidney biopsy plays a crucial role in diagnosing these disorders, enabling the identification of specific histological patterns. These lesions are categorized into organized (such as amyloidosis, immunotactoid glomerulopathy, fibrillary glomerulonephritis, cryoglobulinemic glomerulonephritis, and monoclonal crystalline glomerulopathies) and nonorganized deposits (such as monoclonal Ig deposition disease and proliferative glomerulonephritis with monoclonal Ig deposits) based on the characteristics of immunofluorescence findings and the ultrastructural appearance of deposits on electron microscopy. This review aims to provide an update, highlight, and discuss clinicopathological aspects such as definition, epidemiology, clinical manifestations, mechanisms of kidney injury, histological features, and diagnostic procedures.

Paraproteinaemic keratopathy simulating a crystalline keratopathy.

BACKGROUND: Paraproteinemic keratopathy is a rare disorder characterized by the bilateral accumulation of polychromatic deposits diffusely in all corneal layers together or not with diffuse or patchy pseudo lipid deposits. We present an atypical case of paraproteinemic keratopathy which lead to an initial misdiagnosis of infectious crystalline keratopathy. CASE PRESENTATION: a 69-year-old woman with an asymptomatic keratopathy detected during a cataract intervention. Slit-lamp examination revealed several hyper refringent subepithelial foci with fern-shaped branches, resembling crystalline keratopathy, in her left eye. Anterior segment optical coherence tomography revealed exclusively subepithelial hyperreflective lesions limited to the anterior stroma. The progressive bilateralization and progression of the condition prompted us to include other entities with crystalline corneal deposits in our differential diagnosis. Hematological analysis showed a high number of free Kappa light chains. Despite the typical clinical appearance of crystalline keratopathy, the atypical evolution and test results led us to consider that monoclonal gammopathy could be the cause of this entity. CONCLUSIONS: Paraproteinemic keratopathy may present in its early stages as a unilateral subepithelial crystalline keratopathy. Thus, it must always be taken into account in the differential diagnosis of any crystalline keratopathy, particularly when there are no predisposing factors for an infectious crystalline keratopathy. Early recognition of this rare entity is important to address the associated potentially serious systemic disease.

Massive arterial and venous thrombosis from smouldering multiple myeloma: further evidence for monoclonal gammopathy of thrombotic significance.

A man in his 40s presented to the emergency department after 2 weeks of abdominal pain and bloating. Radiological investigations revealed multiple unusual sites of thrombosis, including large thrombi in his portal and mesenteric veins, and a left ventricular thrombus with resultant embolic infarcts to his spleen, kidneys, coronary arteries and brain. Standard causes of underlying thrombophilia were excluded. A serum protein electrophoresis and serum-free light chains, with subsequent bone marrow biopsy, lead to the diagnosis of smouldering multiple myeloma (sMM), albeit an unusual presentation with severe clinical sequelae. Although sMM is known to be associated with an increased risk of venous thromboembolism, it is not recognised to cause thrombosis in both venous and arterial vascular beds simultaneously. Physicians encountering patients with multiple thrombi in unusual vascular beds without clear aetiology should consider an underlying monoclonal gammopathy in their list of differentials.

[Pulmonary light chain deposition disease from a respiratory physician's perspective].

Pulmonary light chain deposition disease (PLCDD) is a rare monoclonal immunoglobulin deposition disease characterized by the deposition of specific immunoglobulin light chains in lung tissue. In its early stages, PLCDD presents with mild clinical symptoms, while pulmonary imaging shows multiple nodules and thin-walled cysts. Pathologically, there is a deposition of eosinophilic amorphous protein-like material in the tissues, which stains negative for Congo red. The exact pathological mechanism of PLCDD remains unclear, and its clinical presentation lacks specificity. Challenges associated with this condition include difficulties in diagnosis, selection and evaluation of treatment options, lack of clear monitoring criteria, and standards for prognosis assessment. Further research is needed to elucidate the pathogenesis of PLCDD, to establish standardized diagnostic and therapeutic protocols, and to evaluate treatment efficacy and prognostic factors.