A Man with Paraneoplastic Retinopathy plus Small Fiber Polyneuropathy Associated with Waldenström Macroglobulinemia (Lymphoplasmacytic Lymphoma): Insights into Mechanisms

The Cutaneous Pathology of Erythromelalgia and Its Role in Establishing Critical Clues Regarding Pathogenesis

ABSTRACT

Erythromelalgia, a rare cutaneous pain syndrome, is characterized by acral burning pain and flushing, often alleviated by cold and rest. Primary erythromelalgia is caused by gain-of-function mutations of genes encoding for sodium channels, resulting in hyperexcitability of pain signaling neurons. Autoimmunity and hematologic dyscrasias such as thrombocythemia have been implicated in secondary erythromelalgia. The pathology of this rare disease remains poorly defined. The Weill Cornell dermatopathology database was analyzed for acral biopsies procured from patients here there was a clinical concern for erythromelalgia. We identified 9 patients with clinical diagnoses of erythromelalgia who had a skin biopsy from an affected area. The female-to-male ratio was 2:1. Three of 9 individuals had concurrent diagnoses of autoimmune disease including vitiligo, lupus erythematosus, and psoriatic arthritis. Biopsies showed superficial vascular ectasia in association with microvascular C5b-9 and variable upregulation of type I interferon expression in endothelial cells. CD56 stain revealed diminished autonomic innervation of the eccrine coil and arteries, mirroring similar autonomic denervation seen in small fiber neuropathy. This study suggests that erythromelalgia is a dysautonomia syndrome with reproducible findings on biopsy, hallmarked by vascular ectasia and denervation of the eccrine coil and arteries. In addition, there is a potential link to immune and nonimmune-based microvascular compromise.

Clinical Outcomes of Therapeutic Interventions for Autoimmune Retinopathy: A Meta-analysis and Systematic Review

Topic

Autoimmune retinopathy (AIR) is a group of rare inflammatory diseases treated with immunosuppression; however, there is no treatment consensus. This meta-analysis and review aims to investigate treatment effectiveness in slowing AIR progression.

Clinical Relevance

Autoimmune retinopathy is a group of diseases characterized by progressive vision loss that is both difficult to diagnose and treat. While there is some consensus regarding diagnostic criteria, evidence-based treatment consensus remains poorly understood. Current first-line treatment is systemic steroids and conventional steroid-sparing agents. However, patients often experience treatment failure and systemic adverse effects with these medications. Understanding the effect of medications on slowing multiple visual outcomes in AIR can help to guide future treatment protocols.

Methods

PubMed, Cochrane Library, Embase, and ClinicalTrials.gov were systematically searched from inception to November 2023. Included studies treated patients with AIR with systemic, local, and biologic therapy and reported visual acuity (VA), visual field (VF), cystoid macular edema (CME), electroretinogram, central retinal thickness (CRT), and/or ellipsoid zone (EZ) loss. Risk of bias was assessed using the Critical Appraisal Skills Programme checklist. Data for meta-analysis were pooled using a random-effects model.

Results

Analysis of 40 case reports demonstrated that treatment type significantly affects the improvement of VA in patients with nonparaneoplastic retinopathy. Meta-analysis of 12 studies demonstrated that any treatment decreases the risk of progression of all 6 outcomes. Systemic therapy slows VA loss (risk ratio [RR] = 0.04, 95% confidence interval [0.00, 0.91], P = 0.04), VF loss (RR = 0.01, 95% confidence interval [0.00, 0.14], P = 0.0007), and CME (RR = 0.02, 95% confidence interval [0.00, 0.34], P = 0.007). Local therapy slows VA loss (RR = 0.02, 95% confidence interval [0.00, 0.12], P < 0.00001), CME (RR = 0.06, 95% confidence interval [0.01, 0.43], P = 0.005), CRT loss (RR = 0.02, 95% confidence interval [0.00, 0.36], P = 0.007), and EZ loss (RR = 0.31, 95% confidence interval [0.14, 0.70], P = 0.004). Biologics slow VA loss (RR = 0.28, 95% confidence interval [0.12, 0.65], P = 0.003), VF loss (RR = 0.25, 95% confidence interval [0.15, 0.42], P < 0.00001), and CRT loss (RR = 0.19, 95% confidence interval [0.04, 0.79], P = 0.02).

Conclusion

Systemic therapy significantly reduces the risk of progressive visual loss. Local therapy significantly decreases the risk of both progressive visual loss and retinal morphology loss, and therefore may offer precise targeting of the retina. Biologics significantly reduce both functional and morphological retinal changes. Immunosuppressive therapy may slow AIR progression; however, additional research is needed to assess long-term outcomes.

Financial Disclosures

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

The role of antibodies in small fiber neuropathy: a review of currently available evidence

Small fiber neuropathy (SFN) is a peripheral nerve condition affecting thin myelinated Aδ and unmyelinated C-fibers, characterized by severe neuropathic pain and other sensory and autonomic symptoms. A variety of medical disorders can cause SFN; however, more than 50% of cases are idiopathic (iSFN). Some investigations suggest an autoimmune etiology, backed by evidence of the efficacy of IVIG and plasma exchange. Several studies suggest that autoantibodies directed against nervous system antigens may play a role in the development of neuropathic pain. For instance, patients with CASPR2 and LGI1 antibodies often complain of pain, and in vitro and in vivo studies support their pathogenicity. Other antibodies have been associated with SFN, including those against TS-HDS, FGFR3, and Plexin-D1, and new potential targets have been proposed. Finally, a few studies reported the onset of SFN after COVID-19 infection and vaccination, investigating the presence of potential antibody targets. Despite these overall findings, the pathogenic role has been demonstrated only for some autoantibodies, and the association with specific clinical phenotypes or response to immunotherapy remains to be clarified. The purpose of this review is to summarise known autoantibody targets involved in neuropathic pain, putative attractive autoantibody targets in iSFN patients, their potential as biomarkers of response to immunotherapy and their role in the development of iSFN.

The utility of the normal thin section skin biopsy in the assessment of systemic/extracutaneous disease and small fiber neuropathy

Diseases reflective of multiorgan vascular injury of diverse etiology, peripheral nerve disease, dysautonomia syndromes, and intravascular lymphoma may exhibit abnormalities on a normal skin biopsy that may be instrumental in establishing a diagnosis. A retrospective review of our database was conducted to uncover cases where a normal skin biopsy was performed to rule in or out such systemic diseases as complement-driven thrombotic microvascular disease (including atypical hemolytic uremic syndrome, posttransplant thrombotic microangiopathy, and severe or critical COVID-19), systemic capillary leak syndrome, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) intravascular B cell lymphoma, small fiber neuropathy, dysautonomia syndromes, and mast cell activation syndrome. Among the special studies were immunohistochemical staining to detect C5b-9, CD56, and myxovirus resistance protein A, as well as mast cell, B and T cell markers. Characteristic patterns were critical in establishing diagnoses such as : increased C5b-9 microvascular deposition in the deltoid area (atypical hemolytic uremic syndrome, posttransplant thrombotic microangiopathy, catastrophic antiphospholipid antibody syndrome, and severe or critical COVID-19); enhanced type I interferon signaling (systemic capillary leak syndrome); ultrastructural arteriopathic changes (CADASIL); reduced cutaneous autonomic innervation in the lower extremities (small fiber neuropathy and postural orthostatic tachycardia syndrome); presence of intravascular lymphocytes on biopsy of abdominal, thigh, and buttock skin (intravascular B cell lymphoma); and a higher than normal density of mast cells in the absence of other inflammatory cell types (mast cell activation syndrome). The skin is clearly a critical window for understanding extracutaneous disease, a concept well exemplified by the myriad of diseases suggested by the microscopic and/or ultrastructural examination of clinically normal skin and therefore establishing the normal skin biopsy as an important tool for understanding certain extracutaneous reactive, neoplastic and paraneoplastic syndromes as well as small fiber neuropathy.

The Spectrum of Ocular Manifestations in Patients with Waldenström's Macroglobulinemia

PURPOSE

To investigate the ocular manifestations in 91 Waldenström's macroglobulinemia (WM) patients.

METHODS

Retrospective, cross-sectional, observational analysis.

RESULTS

Ocular impairments, detected in 19 patients, included flame-shaped hemorrhages, venous sausaging, papilledema, macular detachments, or central retinal vein occlusion in 16 patients; paraproteinemic keratopathy in 2; and a CANOMAD syndrome in 1. Best-corrected visual acuity was ≥0.5 logMAR units in 11 of 38 eyes. Intraocular pressure was increased in seven eyes. Genetic analysis in seven patients showed a mutation in the MYD88 gene in six patients and a nonsense mutation in the CXCR4 gene in five patients. Plasmapheresis followed by chemotherapy with or without the addition of rituximab resulted in improvement or normalization of the ophthalmological findings in 15 patients.

CONCLUSION

The ocular manifestations of WM are protean and potentially sight threatening. Recent advances in genomic profiling and chemotherapy have remarkably improved the hematological and ophthalmological outcomes of these patients.

Paraneoplastic Neuropathies: What's New Since the 2004 Recommended Diagnostic Criteria

The diagnostic criteria published by the PNS (Paraneoplastic Neurological Syndromes) Euronetwork in 2004 provided a useful classification of PNS, including paraneoplastic neuropathies. Subacute sensory neuronopathy (SSN) was the most frequently observed peripheral PNS, whereas other forms of neuropathy, as sensory polyneuropathy, sensorimotor polyneuropathy, demyelinating neuropathies, autonomic neuropathies, and focal nerve or plexus lesions, were less frequent. At the time of publication, the main focus was on onconeural antibodies, but knowledge regarding the mechanisms has since expanded. The antibodies associated with PNS are commonly classified as onconeural (intracellular) and neuronal surface antibodies (NSAbs). Since 2004, the number of antibodies and the associated tumors has increased. Knowledge has grown on the mechanisms underlying the neuropathies observed in lymphoma, paraproteinemia, and multiple myeloma. Moreover, other unrevealed mechanisms underpin sensorimotor neuropathies and late-stage neuropathies, where patients in advanced stages of cancer—often associated with weight loss—experience some mild sensorimotor neuropathy, without concomitant use of neurotoxic drugs. The spectrum of paraneoplastic neuropathies has increased to encompass motor neuropathies, small fiber neuropathies, and autonomic and nerve hyperexcitability syndromes. In addition, also focal neuropathies, as cranial nerves, plexopathies, and mononeuropathies, are considered in some cases to be of paraneoplastic origin. A key differential diagnosis for paraneoplastic neuropathy, during the course of cancer disease (the rare occurrence of a PNS), is chemotherapy-induced peripheral neuropathy (CIPN). Today, novel complications that also involve the peripheral nervous system are emerging from novel anti-cancer therapies, as targeted and immune checkpoint inhibitor (ICH) treatment. Therapeutic options are categorized into causal and symptomatic. Causal treatments anecdotally mention tumor removal. Immunomodulation is sometimes performed for immune-mediated conditions but is still far from constituting evidence. Symptomatic treatment must always be considered, consisting of both drug therapy (e.g., pain) and attempts to treat disability and neuropathic pain.

Autoimmune retinopathy associated with monoclonal gammopathy of undetermined significance: a case report

Background

Monoclonal gammopathy of undetermined significance (MGUS) is a plasma cell dyscrasia and precursor to multiple myeloma. It has known ocular manifestations, but has not previously been shown to have an association with autoimmune retinopathy.

Case presentation

A 57 year-old female presented with 1 year of progressive, bilateral, peripheral vision loss, photopsias, and nyctalopia. Her fundus examination and extensive ancillary testing were concerning for hereditary versus autoimmune retinopathy. The patient was found to have anti-retinal antibodies against carbonic anhydrase II and enolase proteins with a negative genetic retinal dystrophy panel. Malignancy work-up was negative, but the patient was diagnosed with MGUS, a premalignant condition. The patient was treated with immunosuppressive therapies, with rituximab demonstrating the most robust therapeutic response with respect to patient symptoms and ophthalmic testing.

Conclusions

MGUS should be considered as a potential etiology of autoimmune retinopathy in patients without other autoimmune or malignant disease processes. Immunosuppressive therapy may be helpful in limiting disease progression, with rituximab showing efficacy in retinopathy refractory to other agents.

Association of small-fiber polyneuropathy with three previously unassociated rare missense SCN9A variants

BACKGROUND

Small fiber polyneuropathy (SFN) involves ectopic firing and degeneration of small-diameter, somatic/autonomic peripheral axons. Causes include diabetes, inflammation and rare pathogenic mutations, including in SCN9-11 genes that encode small fiber sodium channels.

AIMS

The aim of this study is to associate a new phenotype-immunotherapy-responsive SFN-with rare amino acid-substituting SCN9A variants and present potential explanations.

METHODS

A retrospective chart review of two Caucasians with skin biopsy confirmed SFN and rare SCN9A single nucleotide polymorphisms not previously reported in neuropathy.

RESULTS

A 47-year-old with 4 years of disabling widespread neuropathic pain and exertional intolerance had nerve- and skin biopsy-confirmed SFN, with blood tests revealing only high-titer antinuclear antibodies and low complement C4 consistent with B cell dysimmunity. Six years of intravenous immunoglobulin (IVIg) therapy markedly improved sensory and autonomic symptoms and normalized his neurite density. After whole exome sequencing revealed a potentially pathogenic SCN9A-A3734G variant, sodium channel blockers were tried. Herpes zoster left a 32-year-old with disabling exertional intolerance ("chronic fatigue syndrome"), postural syncope and tachycardia, arm and leg paresthesias, reduced sweating, and distal hairloss. Screening revealed antinuclear and potassium channel autoantibodies, so prednisone and then IVIg were prescribed with great benefit. During 4 years of immunotherapy, his symptoms and function improved, and all abnormal biomarkers (autonomic testing and skin biopsies) normalized. Whole exome sequencing then revealed two nearby compound heterozygous SCN9A variants that were computer-predicted to be deleterious.

CONCLUSIONS

These cases newly associate three novel amino acid-substituting SCN9A variants with immunotherapy-responsive neuropathy. Only larger studies can determine whether these are contributory or coincidental, but they associate new variants with moderate or high likelihood of pathogenicity with a new highly related phenotype.

Seeing is believing: A review of apheresis therapy in the treatment of ophthalmologic disease

Apheresis procedures have a role in treatment of disparate diseases involving many different organ systems. Often the disease processes where apheresis plays a role in treatment are considered "orphan diseases"-relatively rare disease processes that lack specific pharmaceutical agents or established treatment protocols. Many of these disease processes can affect the eye with devastating results for the eyesight of these patients. The unique ability of apheresis to affect disease by modifying blood plasma and modulating disease-causing agents therein renders apheresis procedures valuable tools in the treatment of certain ophthalmologic diseases. This review comprehensively evaluates the role of apheresis in the treatment of ophthalmologic diseases of the eye and surrounding orbit including age-related macular degeneration, bilateral diffuse uveal melanocytic proliferation, paraneoplastic retinopathy, atopic keratoconjunctivitis, sympathetic ophthalmia, and endocrine-associated ophthalmopathy. Apheresis procedure parameters are provided for the apheresis practitioner based on review of the relevant literature.

Outcomes in Autoimmune Retinopathy Patients Treated With Rituximab

PURPOSE

To evaluate clinical and ancillary testing, including adaptive optics, outcomes in autoimmune retinopathy (AIR) patients treated with rituximab.

DESIGN

Retrospective, interventional case series.

METHODS

patients: Sixteen AIR patients treated with rituximab.

OBSERVATION PROCEDURES

All patients were treated with a loading and maintenance dose schedule of intravenous rituximab. Visual acuity (VA), electroretinography (ERG), and spectral-domain optical coherence tomography (SDOCT) and visual field (VF) results were recorded. A subset of patients was also imaged using adaptive optics scanning laser ophthalmoscopy (AO-SLO).

MAIN OUTCOME MEASURES

Rates of VA change before vs after rituximab initiation were compared with mixed-model linear regression.

RESULTS

The rate of visual decline was significantly less after rituximab initiation compared with the rate of visual decline prior to rituximab initiation (P = .005). Seventy-seven percent of eyes had stable or improved VA 6 months after rituximab initiation. Amplitudes and implicit times on ERG, mean deviation on VF, central subfield mean thickness, and total macular volume did not decrease to a significant degree over the rituximab treatment period. Six eyes had serial AO-SLO imaging. Cone densities did not change significantly over the treatment period.

CONCLUSION

VA was stable or improved in a majority of AIR patients while they were being treated with rituximab. OCT and ERG parameters, as well as AO-SLO cone densities, were stable during treatment. Studies with additional patients and longer follow-up periods are needed to further explore the utility of rituximab in the management of AIR.

Autoimmunity in visual loss

There are a number of autoimmune disorders which can affect visual function. There are a very large number of mechanisms in the visual pathway which could potentially be the targets of autoimmune attack. In practice it is the retina and the anterior visual pathway (optic nerve and chiasm) that are recognised as being affected in autoimmune disorders. Multiple Sclerosis is one of the commonest causes of visual loss in young adults because of the frequency of attacks of optic neuritis in that condition, however the basis of the inflammation in Multiple Sclerosis and the confirmation of autoimmunity is lacking. The immune process is known to be highly unusual in that it is not systemic and confined to the CNS compartment. Previously an enigmatic partner to Multiple Sclerosis, Neuromyelitis Optica is now established to be autoimmune and two antibodies - to Aquaporin4 and to Myelin Oligodendrocyte Glycoprotein - have been implicated in the pathogenesis. The term Chronic Relapsing Inflammatory Optic Neuropathy is applied to those cases of optic neuritis which require long term immunosuppression and hence are presumed to be autoimmune but where no autoimmune pathogenesis has been confirmed. Optic neuritis occurring post-infection and post vaccination and conditions such as Systemic Lupus Erythematosus and various vasculitides may cause direct autoimmune attack to visual structures or indirect damage through occlusive vasculopathy. Chronic granulomatous disorders such as Sarcoidosis affect vision commonly by a variety of mechanisms, whether and how these are placed in the autoimmune panoply is unknown. As far as the retina is concerned Cancer Associated Retinopathy and Melanoma Associated Retinopathy are well characterised clinically but a candidate autoantibody (recoverin) is only described in the former disorder. Other, usually monophasic, focal retinal inflammatory disorders (Idiopathic Big Blind Spot Syndrome, Acute Zonal Occult Outer Retinopathy and Acute Macular Neuroretinitis) are of obscure pathogenesis but an autoimmune disorder of the post-infectious type is plausible. Visual loss in autoimmunity is an expanding field: the most significant advances in research have resulted from taking a well characterised phenotype and making educated guesses at the possible molecular targets of autoimmune attack.