The Peripheral Neuropathies of POEMS Syndrome and Castleman Disease

Peripheral Nervous System (PNS) Myelin Diseases

This is a review of inherited and acquired causes of human demyelinating neuropathies and a subset of disorders that affect axon-Schwann cell interactions. Nearly all inherited demyelinating neuropathies are caused by mutations in genes that are expressed by myelinating Schwann cells, affecting diverse functions in a cell-autonomous manner. The most common acquired demyelinating neuropathies are Guillain-Barré syndrome and chronic, inflammatory demyelinating polyneuropathy, both of which are immune-mediated. An additional group of inherited and acquired disorders affect axon-Schwann cell interactions in the nodal region. Overall, these disorders affect the formation of myelin and its maintenance, with superimposed axonal loss that is clinically important.

Unmet Clinical Needs in the Management of Idiopathic Multicentric Castleman Disease: A Consensus-based Position Paper From an ad hoc Expert Panel

Castleman disease describes a group of heterogeneous clinicopathological disorders now included in the tumor-like lesions with B-cell predominance of the World Health Organization classification. Managing idiopathic multicentric Castleman disease (iMCD) is challenging, because few systematic studies or comparative randomized clinical trials have been conducted. International, consensus evidence-based guidelines for iMCD were published in 2018, but gaps in the therapeutic options for difficult-to-treat patients, who do not respond to siltuximab and other conventional therapies, still exist. This article presents the results of group discussion among an ad hoc constituted Panel of Italian experts to identify and address unmet clinical needs (UCNs) in managing iMCD. Recommendations on the appropriateness of clinical decisions and proposals for new research concerning the identified UCNs were issued through formalized multiple-step procedures after a comprehensive analysis of the scientific literature. The following key UCNs were addressed: strengthening the diagnostic certainty in iMCD patients before planning first-line therapy; management of siltuximab therapy; choice and management of immune-modulating, or chemotherapy agents in patients resistant/intolerant to siltuximab therapy. While most of the conclusions reached by the Panel are consistent with the existing guidelines, some alternative therapeutic options were stressed, and the discussion contributed to bringing forth the issues that need further investigation. Hopefully, this comprehensive overview will improve the practice of iMCD and inform the design and implementation of new studies in the field.

Recent Advances in the Treatment and Supportive Care of POEMS Syndrome

POEMS is a rare clonal plasma cell disorder characterized by multi-systemic features that include demyelinating peripheral neuropathy, organomegaly, endocrinopathy, presence of monoclonal proteins (M-protein), and skin changes. Even though the pathophysiology is poorly understood, recent studies suggest that both clonal and polyclonal plasmacytosis leading to the production of pro-inflammatory cytokines and angiogenic mediators play the central role. These mediators including vascular endothelial growth factor (VEGF) are the driving forces of the syndrome. The diagnosis of POEMS is not always straight forward and often the diagnosis is delayed. It is based on fulfilling mandatory criteria of polyradiculoneuropathy and monoclonal protein and the presence of one major criterion (Castleman disease, sclerotic bone lesions, or elevated VEGF), and at least one minor criterion. Due to the presence of neuropathy, it can be confused with chronic inflammatory demyelinating polyradiculopathy (CIDP), and if thrombocytosis and splenomegaly are present, it can be confused with myeloproliferative neoplasms. Due to the rarity of the syndrome, clear guidelines for treatment are still lacking. Immediate treatment targeting the underlying plasma cell proliferation results in a dramatic response in most patients. The key is early diagnosis and immediate anti-plasma cell directed therapy for the best clinical outcomes. For patients with disseminated disease as defined by bone marrow involvement or more than three osteosclerotic bone lesions, high-dose chemotherapy with autologous hematopoietic stem cell transplant (ASCT) yields durable responses and is the preferred treatment in eligible patients. For patients with localized bony disease, radiotherapy has proven to be very effective. Lenalidomide and dexamethasone is a proven therapy in patients ineligible for ASCT. In this review article, we tackle the diagnostic approach and discuss the latest treatment modalities of this rare debilitating disease.

Immunoglobulin M Monoclonal Gammopathies of Clinical Significance

Immunoglobulin M monoclonal gammopathy of undetermined significance (MGUS) comprises 15-20% of all cases of MGUS. IgM MGUS is distinct from other forms of MGUS in that the typical primary progression events include Waldenstrom macroglobulinaemia and light chain amyloidosis. Owing to its large pentameric structure, IgM molecules have high intrinsic viscosity and precipitate more readily than other immunoglobulin subtypes. They are also more commonly associated with autoimmune phenomena, resulting in unique clinical manifestations. Organ damage attributable to the paraprotein, not fulfilling criteria for a lymphoid or plasma cell malignancy has recently been termed monoclonal gammopathy of clinical significance (MGCS) and encompasses an important family of disorders for which diagnostic and treatment algorithms are evolving. IgM related MGCS include unique entities such as cold haemagglutinin disease, IgM related neuropathies, renal manifestations and Schnitzler's syndrome. The diagnostic approach to, and management of these disorders differs significantly from other categories of MGCS. We describe a practical approach to the evaluation of these patients and our approach to their treatment. We will also elaborate on the key unmet needs in IgM MGCS and highlight potential areas for future research.

POEMS Syndrome: Presented as Idiopathic Multicentric Castleman Disease of Plasma Cell Variant for Eight Years and Dramatic Treatment with Siltuximab Followed by Autologous Peripheral Blood Stem Cell Transplantation

Background: POEMS syndrome (POEMS) is a rare plasma cell clonal paraneoplastic syndrome consisting of polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and skin changes presenting with idiopathic multicentric Castleman disease (iMCD) histology, the treatment of which has not yet been well established. iMCD is also a distinctive rare non-clonal lymphoproliferative disorder, of which dramatic response to Siltuximab, a monoclonal anti-IL-6 antibody, has been reported recently. Methods: the differential diagnosis between POEMS and iMCD can be very challenging because of the identical histology, overlapping similar symptoms such as polyneuropathy, and vital signs insidiously presented to diagnose POEMS. Results: here, we report the case of a 53-year-old man with iMCD treated for 8 years developing sequential polyneuropathy, monoclonal gammopathy, and bone lytic lesions, all of which were confirmed after his iMCD achieved complete remission resulting from siltuximab administration and finally confirmed as POEMS. Conclusions: we describe the clinical ambiguity of disease presenting that we can face in the real world between iMCD and POEMS and emphasise careful, enduring observation lasting several years.

Not the final diagnosis: from Addison's disease to POEMS syndrome: a case report and literature review

We report the case of a 47-year-old male patient with pigmentation of the head, face and hands, who was initially diagnosed as having primary adrenal insufficiency (Addison's disease). Laboratory testing, imaging and physical examination revealed subclinical hypothyroidism, high circulating prolactin and oestradiol concentrations, gynaecomastia, lymphadenopathy, splenomegaly and weakness of both lower limbs. These findings led us to consider whether a single or multiple diseases were present in this patient. Indeed, Addison's disease can represent one aspect of a wider systemic disease. Therefore, we performed further examinations, and found high serum M protein (5.1%) and vascular endothelial growth factor [1005.30 pg/mL (normal range 0 to 142 pg/mL)] concentrations. As a consequence, we diagnosed polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy and skin changes (POEMS) syndrome. Consequently, when a single disease cannot fully explain the multiple symptoms and signs of one patient, clinicians should consider the possibility of the presence of a wider syndrome and undertake more detailed diagnostic testing.

Rare Association Between Idiopathic Multicentric Castleman Disease, Nephrotic Syndrome and Polyneuropathy in an Immunocompetent Patient

Multicentric Castleman disease (MCD) represents a group of poorly understood lymphoproliferative disorders related to proinflammatory hypercytokinaemia. In immunocompetent patients the aetiology is still unknown, hence the designation of idiopathic MCD (iMCD). To successfully diagnose iMCD, diagnostic criteria must be fulfilled and a large array of alternative diagnoses excluded. Peripheral neuropathy and nephropathy are relatively common findings in cases associated with POEMS syndrome, but very rarely reported in iMCD. We present the case of a 64-year-old man with iMCD (HIV- and HHV-8-negative) with nephrotic syndrome and severe motor polyneuropathy. Alternative diagnoses were excluded. The patient was treated with intravenous glucocorticoid followed by rituximab. Complete clinical and laboratory remission was achieved and maintained at the 2-year follow-up.

LEARNING POINTS

iMCD is a lymphoproliferative disease in immunocompetent patients with no known cause.To diagnose iMCD major and minor criteria must be fulfilled, and alternative diagnoses must be excluded.Nephrotic syndrome and motor polyneuropathy are rare in iMCD and all alternative diagnoses must be excluded before relating all of these.

Update on the Diagnosis and Treatment of POEMS (Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal Gammopathy, and Skin Changes) Syndrome: A Review

Importance

POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) syndrome is a rare plasma cell disorder characterized by demyelinating peripheral neuropathy and clonal plasma cell proliferation. Clinical manifestations are believed to be associated with a surge of inflammatory and angiogenic mediators, including interleukins and vascular endothelial growth factor (VEGF), elicited by clonal and polyclonal plasma cells. The clinical manifestations of POEMS syndrome can be debilitating; therefore, early diagnosis is essential. This review discusses several aspects of POEMS syndrome and includes the most recently published findings, with a special emphasis on diagnosis and treatment strategies.

Observations

POEMS syndrome may be underdiagnosed because of its rarity, and it can be mistaken for chronic inflammatory demyelinating polyneuropathy; this misdiagnosis may lead to delayed therapy and progressive worsening of symptoms, especially neuropathy. Therefore, in addition to measurement of the VEGF level, patients with a monoclonal protein detected in blood and/or urine and neuropathy should be evaluated for POEMS syndrome with use of imaging to assess whether sclerotic bone lesions, effusions, and organomegaly are present. Clinical trials are scant, and treatment is largely based on small case series in which plasma cell-directed therapies, borrowed from the myeloma armamentarium, were used. High-dose melphalan and autologous hematopoietic cell transplantation may be offered to eligible patients. Lenalidomide and dexamethasone can be prescribed for patients who are ineligible for transplants. The main goals of therapy are to attain complete hematologic and VEGF responses and to reduce symptoms, although it may take up to 3 years for neurologic deficits to be ameliorated.

Conclusions and Relevance

POEMS syndrome should be considered in the differential diagnosis for patients who have peripheral neuropathy and paraproteinemia among other multisystem manifestations. The syndrome can be debilitating if not recognized early in its course; thus, appropriate diagnosis and treatment are important for optimal clinical outcomes.

Clinical characteristics, risk factors, and outcomes of POEMS syndrome

Objective

POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin lesions) is a paraneoplastic disorder resulting in severe neurologic disability. Understanding the clinical, laboratory, neurophysiologic, and histopathologic features as well as treatment responses of POEMS will assist in more accurate and timely diagnosis, risk stratification, and effective management.

Methods

This was a retrospective longitudinal cohort study from 1998 to March 2019, with 7,184 person-months of follow-up time. Hospital databases were used to collate presenting features, investigations, therapies, and response.

Results

One hundred patients were included with a median follow-up time of 59 months (range, 1–252). Mean symptom onset to diagnosis was 15 months (range, 1–77), with 54% of patients initially misdiagnosed with chronic inflammatory demyelinating polyneuropathy. Median number of multisystem features at diagnosis was 7. Ninety-six (96%) presented with neuropathy, which was length-dependent in 93 (93%) and painful in 75 (75%). At diagnosis, 35% of patients were wheelchair or bedbound, with median Overall Neuropathy Limitation Score of 6, improving to 3 following treatment (p < 0.05). Five-year survival was 90% and 82% at 10 years, with 5- and 10-year progression-free survival of 65% and 53%. Nontreatment with autologous stem cell transplantation, nonhematologic response, and non–vascular endothelial growth factor response are significant risk factors in multivariate analysis to predict progression or death. Risk factors are incorporated to develop a risk score enabling stratification of high- and low-risk cases.

Conclusions

POEMS syndrome is a rare multisystem condition with delayed diagnosis and poor neurologic function at presentation. Therapy has favorable outcomes. Patients at high risk of death or progression can be identified, which may allow for more active monitoring and influence management.

Sclerodermalike syndromes: Great imitators

Sclerodermalike syndromes (SLSs) comprise diseases with mucin deposition (eg, scleromyxedema, scleredema), with eosinophilia (eg, eosinophilic fasciitis), metabolic or biochemical abnormalities (eg, nephrogenic systemic fibrosis), or endocrine disorders (eg, POEMS syndrome, or polyneuropathy, organomegaly, endocrinopathy, monoclonal lymphoproliferative disorder, and hypothyroidism). Chronic graft-versus-host disease may also show sclerodermalike skin changes. Inherited progeria syndromes with early aging (eg, Werner syndrome) and a heterogeneous group of hereditary disorders with either skin thickening (eg, stiff skin syndrome) or atrophy and tightening (eg, acrogeria) can also imitate classic systemic sclerosis (SSc). In addition, SLSs can be provoked by several drugs, chemicals, or even physical injury (eg, trauma, vibration stress, radiation). In SLSs, the distribution of skin involvement seems to be atypical compared with SSc. The acral skin involvement is usually missing, and lack of Raynaud phenomenon, scleroderma-specific antinuclear antibodies, the absence of scleroderma capillary pattern, and internal organ manifestations indicate the presence of an SLS. Skin involvement is sometimes nodular, and the underlying tissues can also be affected. For the differential diagnosis, a skin biopsy of the deeper layers including fascia and muscle is required. Histology does not always allow differentiation between SSc and SLSs; therefore, the diagnosis is often based on the distribution, quality of cutaneous involvement, and other accompanying clinical features.

An update on the diagnosis and management of the polyneuropathy of POEMS syndrome

POEMS syndrome is a rare, chronic, disabling paraneoplastic disorder characterized by peripheral neuropathy, organomegaly, endocrinopathy, monoclonal plasma cells disorder and skin changes. Diagnosis relies on the fulfillment of a set of clinical criteria of which polyneuropathy and a monoclonal plasma cell dyscrasia are early and essential features. Treatment may be either local or systemic and is aimed at the monoclonal plasma cell disorder. Our knowledge of the pathogenesis underlying the POEMS syndrome has advanced greatly over the past years, favoring an important progression in the recognition and management of this disorder. Here, we discuss the recent literature that has advanced our knowledge of the pathogenesis and clinical management of the polyneuropathy in POEMS syndrome.