Clinical and immunologic characteristics of melanoma-associated retinopathy syndrome: eleven new cases and a review of 51 previously published cases

Treatment of melanoma-associated retinopathy

OPINION STATEMENT

Melanoma-associated retinopathy is a rare paraneoplastic disorder that is challenging to diagnose and even more difficult to treat. Because of the rarity of the disease, therapy is based on analysis of case series and case reports. Based on evidence from these reports, first-line therapy is cytoreduction of metastatic disease through metastasectomy, chemotherapy, and radiation. This can be combined with intravenous immunoglobulin. For refractory visual symptoms, additional therapies include systemic corticosteroids and plasmapheresis, but the success of these strategies has been limited. Because of the rarity of the disorder, new therapies should be evaluated and reported in the literature to expand our clinical understanding of this autoimmune disease.

Autoantibodies in melanoma-associated retinopathy target TRPM1 cation channels of retinal ON bipolar cells

Melanoma-associated retinopathy (MAR) is characterized by night blindness, photopsias, and a selective reduction of the electroretinogram b-wave. In certain cases, the serum contains autoantibodies that react with ON bipolar cells, but the target of these autoantibodies has not been identified. Here we show that the primary target of autoantibodies produced in MAR patients with reduced b-wave is the TRPM1 cation channel, the newly identified transduction channel in ON bipolar cells. Sera from two well characterized MAR patients, but not from a control subject, stained human embryonic kidney cells transfected with the TRPM1 gene, and Western blots probed with these MAR sera showed the expected band size (∼180 kDa). Staining of mouse and primate retina with MAR sera revealed immunoreactivity in all types of ON bipolar cells. Similar to staining for TRPM1, staining with the MAR sera was strong in dendritic tips and somas and was weak or absent in axon terminals. This staining colocalized with GFP in Grm6-GFP transgenic mice, where GFP is expressed in all and only ON bipolar cells, and also colocalized with Gα(o), a marker for all types of ON bipolar cells. The staining in ON bipolar cells was confirmed to be specific to TRPM1 because MAR serum did not stain these cells in a Trpm1(-/-) mouse. Evidence suggests that the recognized epitope is likely intracellular, and the sera can be internalized by retinal cells. We conclude that the vision of at least some patients with MAR is compromised due to autoantibody-mediated inactivation of the TRPM1 channel.

Melanoma-associated retinopathy associated with intranasal melanoma

PURPOSE

To present a case of melanoma-associated retinopathy (MAR) associated with an intranasal melanoma.

CASE REPORT

A 77-year-old Japanese man visited us complaining of night blindness, blurred vision, and color vision difficulties in both eyes. His best-corrected visual acuity was 0.7 in the right and 1.0 in the left eyes. The rod response of the electroretinogram (ERG) was abolished, and the maximum response had a negative waveform. The a-wave of the single-flash cone response was square shaped, and the b-wave was delayed. The ON-response of the long-flash cone ERG was absent, but the OFF-response was preserved. A severe loss of retinal sensitivity was detected by static perimetry. Positron emission tomography showed no abnormal signs. Six months after the initial examination, an intranasal tumor was detected and surgically removed. The final diagnosis based on histopathology was malignant melanoma.

CONCLUSION

Our case demonstrates that MAR can be associated with an intranasal mucosal melanoma. Thus, in cases where the primary lesion cannot be identified in patients with MAR-like symptoms and signs, we recommend that preferential sites of mucosal melanomas be examined.

Retinal disorders

The retina represents part of the central nervous system (CNS). After modifying the neural signal, the axon of the last neuron enters the optic nerve and leaves the eye. In most cases of retinal disease leading to visual loss, the diagnosis will be made by an ophthalmologist after examining the ocular fundus. Some retinal disorders, however, might not be detectable at the time of examination. Those patients will be referred to a neurologist for "unexplained visual loss" when suspecting a lesion behind the optic nerve. Moreover, knowledge of potential retinal abnormalities is useful for the neurologist when seeing patients with CNS disease, which can manifest itself also in the retina. This chapter aims to give an overview about retinal disorders causing no or only few retinal abnormalities, those associated with neurological diseases, as well as the most important retinal diseases involving the tissues of the ocular fundus (vitreous body, retina, pigment epithelium, and the choroid). The most frequently used examination techniques and diagnostic tools are described. Tumors, vascular disease, especially diabetic retinopathy, age-related macular degeneration, chorioretinal inflammatory and toxic disorders, paraneoplastic retinopathies, inherited retinal dystrophies, and retinal involvement in CNS disease such as phakomatoses and multiple sclerosis are discussed.

Anti-γ-enolase autoimmune retinopathy manifesting in early childhood

OBJECTIVE

To describe the clinical, molecular, and serologic findings of a case in which autoimmune retinopathy and early-onset heritable retinal degeneration were both considered in the differential diagnosis.

METHODS

A 3-year-old girl had clinical findings suggestive of a childhood-onset retinal degeneration. Samples of DNA and serum were collected. The coding regions of 11 genes associated with Leber congenital amaurosis were sequenced. The patient's serum reactivity to soluble and insoluble fractions of human retinal protein was compared with that of healthy control subjects (n = 32), patients with inflammatory eye disease (n = 80), and patients with molecularly confirmed retinal degenerations (n = 11). Two-dimensional gel electrophoresis and mass spectrometry were used to identify a protein that corresponded to a reactive band on Western blot.

RESULTS

No plausible disease-causing mutations were identified in any of the retinal disease genes tested. However, the patient's serum showed reactivity to a single retinal antigen of approximately 47 kDa. Two-dimensional gel electrophoresis and mass spectrometry revealed the major reactive species to be neuron-specific enolase (NSE). Autoantibodies targeting NSE were not observed in any healthy control subjects or patients with inflammatory eye disease. However, anti-NSE activity was found in 1 child with molecularly confirmed Leber congenital amaurosis.

CONCLUSION

This patient's clinical and laboratory findings coupled with the recently discovered role of anti-NSE antibodies in canine autoimmune retinopathy suggest that autoantibodies targeting NSE are involved in the pathogenesis of her disease.

CLINICAL RELEVANCE

Infection or inflammation within the retina early in life may lead to an autoimmune phenocopy of early-onset inherited retinal degeneration.

Paraneoplastic vitelliform retinopathy in metastatic cutaneous melanoma

PURPOSE

To report the clinical picture and investigative findings of unusual paraneoplastic retinopathy lesions in a patient with metastatic skin melanoma.

METHODS

A middle-aged man presented with mild blurring of vision in one eye. He had metastatic skin melanoma to the axillary lymph nodes, which was treated by interferon. Fundus photographs showed bilateral unusual multiple vitelliform lesions. Retinal and serologic investigations were performed.

RESULTS

These vitelliform lesions involved the outer retinal layers and retinal pigment epithelium (RPE) as demonstrated by optical coherence tomography and have completely blocked choroidal fluorescence without late staining in angiography. There was only minimal reduction of Arden ratio in electro-oculography, although electroretinography was essentially normal. Antibipolar cells autoantibodies were not detected in this case.

CONCLUSION

This melanoma-related paraneoplastic retinopathy may represent a separate entity from the classic findings in melanoma-associated retinopathy (MAR) syndrome. Optical coherence tomography is helpful to differentiate it from simulating lesions. Recognition of this presentation can help to diagnose the presence of an occult metastaticmelanoma in some cases.

Melanoma-associated retinopathy: a paraneoplastic autoimmune complication

OBJECTIVES

To study 11 patients with melanoma-associated retinopathy (MAR) to clarify the reliability of various methods of diagnostic testing, to determine the underlying antigenic retinal proteins, and to study the clinical histories and types of associated melanomas.

METHODS

Clinical data were obtained from patients with melanoma who developed marked visual problems. Testing included electroretinography, kinetic visual fields, comparative studies of Western blots, and indirect immunohistologic examination to detect antiretinal antibodies, as well as proteomic studies to identify underlying antigenic retinal proteins.

RESULTS

Patients with MAR typically have rapid onset of photopsias, scotomata, and loss of central or paracentral vision. Ophthalmoscopy seldom shows significant changes early, but electroretinograms are abnormal. Results of Western blots and immunohistologic examination can show antiretinal antibodies but not always. Most patients (9 of 11) had a strong family history of autoimmune disorders. Any type of melanoma (cutaneous, choroidal, ciliary body, or choroidal nevi) may be associated with this paraneoplastic autoimmune reactivity. MAR may precede or follow the diagnosis of melanoma. Patients with MAR have the same antigenic retinal proteins that have been associated with cancer-associated retinopathy. In addition, 2 new antigenic retinal proteins, aldolase A and aldolase C, were found.

CONCLUSIONS

There was a high prevalence of positive family histories of autoimmune disease in patients with MAR. To confirm the disorder, multiple clinical and serum diagnostic techniques (Western blot or indirect immunohistologic examination) are needed. Two newly observed antigenic retinal proteins, aldolase A and aldolase C, are associated with MAR.

Retinal Vasculitis

Retinal vasculitis is a sight-threatening intraocular inflammation affecting the retinal vessels. It may occur as an isolated ocular condition, as a manifestation of infectious or neoplastic disorders, or in association with a systemic inflammatory disease. The search for an underlying etiology should be approached in a multidisciplinary fashion based on a thorough history, review of systems, physical examination, and laboratory evaluation. Discrimination between infectious and noninfectious etiologies of retinal vasculitis is important because their treatment is different. This review is based on recently published articles on retinal vasculitis and deals with its clinical diagnosis, its link with systemic diseases, and its laboratory investigation.

Cancer-Induced, Immune-Mediated Ocular Degenerations

The means whereby vision can be lost from a disease located distant from the eye include autoimmunity, with sensitization resulting from extraocular stimuli, a process illustrated here by the immunologic confusion caused by cancers. The uncontrolled proliferation of malignancies commonly involves the expression of components of the central nervous system, but a damaging loss of tolerance is rare. When autoimmunity does develop, organ-specific antigens are more often involved than the more generalized and widely disseminated common neuronal components. A focus upon a single antigen is typical of the immune-mediated paraneoplasia, a collection of syndromes identified by unusual antibody reactions. This review provides an outline of the immunologic trail that led to the recognition of autoimmunity in paraneoplastic ocular degenerations, how specific antibody reactions aid in diagnosis, and the possibility of including antibodies in modes for sight-saving intervention. 'Those who do not know history are destined to repeat it'.

Autoantibody targets and their cancer relationship in the pathogenicity of paraneoplastic retinopathy

Paraneoplastic retinopathies (PR), including cancer-associated retinopathy (CAR) or the closely related melanoma-associated retinopathy (MAR) occur in a small subset of patients with retinal degeneration and systemic cancer. This autoimmune syndrome is characterized by sudden, progressive loss of vision in association with circulating anti-retinal autoantibodies. The PR syndromes are heterogeneous, may produce a number of ocular symptoms, and may be associated with several different neoplasms, including lung, breast, prostate, gynecological, and colon cancer, melanoma, and hematologic malignancies. We examined the onset of retinopathy in correlation to the diagnosis of cancer and the presence of specific anti-retinal autoantibodies in PR patients. In some patients without diagnosed malignant tumors, the onset of ocular symptoms and the presence of autoantibodies preceded the diagnosis of cancer by months to years, including anti-recoverin, anti-transducin-alpha, and anti-carbonic anhydrase II antibodies. Although anti-retinal autoantibodies may not be a good predictor of a specific neoplasm, they can be used as biomarkers for different subtypes of retinopathy. Identification of autoantibodies involved in autoimmune-mediated PR will help elucidate the mechanisms underlying the PR syndromes and develop targeted therapies for these sight-threatening disorders.

A negative electroretinogram (ERG) in a case of probable multiple system atrophy (MSA)

Recent articles have described negative ERGs in a small number of patients with cerebellar degeneration. Five of the previously reported seven cases were hereditary (2/5 had spinocerebellar ataxia-1 (SCA-1) gene mutations) and the other two were sporadic. We report a negative ERG in a case of cerebellar degeneration that differs significantly from earlier cases. The 65-year-old man had a 5-year history of ataxia, unsteady gait, orthostatic hypotension, and bladder and erectile dysfunction, with no family history of neurological or retinal disease. Visual acuity was 20/30 OD, 20/40 OS, but reportedly was never 20/20. His fundus exam showed optic nerve pallor, but otherwise was normal. Visual fields had enlarged blind spots but no central scotomas. Autofluorescence was normal. Photopic flash and 30-Hz ERG responses were normal. Rod b-waves were reduced and delayed. Standard flash a-waves were normal, but the b-waves were smaller than the a-waves. Blood tests were negative for Leber's hereditary optic neuropathy, dominant optic atrophy, and for expansions in SCA genes including SCA-1. This is only the third reported case of sporadic ataxia with a negative ERG. The patient's prominent autonomic dysfunction differs from the previous cases, and meets the clinical criteria for probable multiple system atrophy (MSA). This introduces another possible diagnosis in cases of negative ERGs with ataxia, and suggests that the visual system may be affected in MSA.

Central and Paracentral Visual Field Defects and Driving Abilities

The effect of central and paracentral visual field defects on driving abilities has until now received little attention. To date studies and surveys have concentrated on visual acuity and peripheral field loss. Here we summarise for the first time those diseases causing central visual field defects likely to be associated with binocular visual acuity adequate for driving.

Improvement in visual fields in a patient with melanoma-associated retinopathy treated with intravenous immunoglobulin

Melanoma-associated retinopathy (MAR) is a rare disorder characterized by photopsias, shimmering vision, nyctalopia, and dysfunction of rod photoreceptor cells. We describe a 56-year-old man with metastatic cutaneous melanoma to the lymph nodes and MAR. He underwent resection of the metastasis followed by radiation therapy. Over the ensuing 2 months, visual function worsened so he was treated with intravenous immunoglobulin (IVIg). Visual fields, but not electroretinography, improved steadily over the next year. No evidence of recurrence or metastatic disease has been found. Our patient indicates that even after a reduction or elimination of melanoma tumor burden and presumably the attenuation of the antigenic stimulus driving MAR, this disorder can continue to progress. In this setting, IVIg therapy should be considered a viable treatment option.

Autoimmune retinopathy: a review and summary

Three main forms of autoimmune retinopathy (AIR) have been identified over the last 15 years: cancer-associated retinopathy (CAR), melanoma-associated retinopathy (MAR), and nonneoplastic autoimmune retinopathy (npAIR). In this chapter, the term AIR will be used to encompass all three disorders where there is commonality to their features. Complicating the issue is that AIR can be a secondary complication of other conditions such as retinitis pigmentosa, ocular trauma, birdshot retinopathy, acute zonal occult outer retinopathy (AZOOR), or multiple evanescent white dot syndrome (MEWDS). The many forms of AIR tend to have common clinical features despite the fact that there has been no uniform set of anti-retinal antibodies circulating in these patients. Patients tend to have a wide variance of anti-retinal antibody activity often with three to six different antibodies found on immunoblots. Patients typically present with a sudden onset of photopsia, rapid visual loss, and abnormal electroretinograms (ERGs). Most patients have a panretinal degeneration without pigment deposits.

The negative ERG: clinical phenotypes and disease mechanisms of inner retinal dysfunction

Inner retinal dysfunction is encountered in a number of retinal disorders, either inherited or acquired, as a primary or predominant defect. Fundus examination is rarely diagnostic in these disorders, although some show characteristic features, and careful electrophysiological assessment of retinal function is needed for accurate diagnosis. The ERG in inner retinal dysfunction typically shows a negative waveform with a preserved a-wave and a selectively reduced b-wave. Advances in retinal physiology and molecular genetics have led to a greater understanding of the pathogenesis of these disorders. This review summarizes current knowledge on normal retinal physiology, the investigative techniques used and the range of clinical disorders in which there is predominantly inner retinal dysfunction.

Paraneoplastic syndromes in neuro-ophthalmology

PURPOSE OF REVIEW

The aim of this review is to discuss and highlight the recent advances in our understanding of paraneoplastic syndromes in neuro-ophthalmology and their significance.

RECENT FINDINGS

The pathophysiologic mechanism in neuro-ophthalmic paraneoplastic syndromes involves an immune response triggered by aberrant expression of onconeuronal antigens that cross-react with antigens in the visual system. Recently, 18-fluoro-deoxy-glucose/positron emission tomography with computed tomography scanning has emerged as a useful modality in diagnosing occult tumors responsible for paraneoplastic syndromes. Paraneoplastic optic neuropathy has been recently associated with the anti-CV2/CRMP-5 antibody. The use of serologic analysis of recombinantly expressed clones (SEREX) has led to the identification of new antigens associated with melanoma-associated retinopathy, such as visual arrestin, rhodopsin, titin, and mitofilin. Calcium-channel blockers and alemtuzumab have been found to improve visual function in cancer-associated retinopathy. Rituximab has been found to be effective in childhood opsoclonus-myoclonus syndrome.

SUMMARY

A high index of suspicion is needed to diagnose neuro-ophthalmic paraneoplastic syndromes. There have been recent advances in our understanding of the pathophysiology and treatment of these disorders. This will facilitate early treatment of causative occult tumors and improves the prognosis.

Paraneoplastic neurological syndromes and onconeural antibodies: clinical and immunological aspects

Paraneoplastic neurological syndromes (PNS) are infrequent disorders that are associated with cancer. The syndromes are highly heterogeneous and often affect several areas of the nervous system. Among the most well-known syndromes are paraneoplastic encephalomyelitis, cerebellar degeneration, sensory neuronopathy, and Lambert-Eaton myastenic syndrome. There are various associated tumors, in particular small cell lung cancer, cancer of the breast and ovary, and thymoma. The onset of neurological symptoms often precedes the cancer diagnosis, and the recognition of a paraneoplastic syndrome should lead to immediate search for cancer. The etiology of the paraneoplastic syndromes is believed to be autoimmune. Antibodies to onconeural antigens, expressed in the tumor of the affected individual and in normal neurons, are found in many of the patients. These antibodies are useful markers for paraneoplastic etiology. The pathogenesis of the PNS is uncertain, but cellular immune responses are thought to be the main effector mechanism. The cornerstone of therapy is the identification and treatment of the underlying malignancy. In some of the disorders, immunosuppressive therapy is of additional benefit. The prognosis of the different PNS varies depending on the level of affection and the degree of neuronal death.

Cancer-associated retinopathy (CAR) with electronegative ERG: a case report

Cancer-associated retinopathy (CAR) should be suspected in patients who present with visual symptoms such as rapid unexplained visual loss and seeing shimmering lights, with an abnormal ERG. Electronegative ERG responses are not exclusive to melanoma-associated retinopathy (MAR) but may be seen in CAR as well. We describe a patient with CAR who presented with an electronegative ERG. A 67-year old woman, who presented with complaints of seeing shimmering lights, underwent an extensive ophthalmological and electrophysiological examination. Best-corrected visual acuity was 7/10 in the right and 9/10 in the left eye. Goldmann visual fields showed relative central scotomata and concentric narrowing. Slit-lamp and fundus examination were normal as was fluorescein angiography. Rod-specific ERG responses were severely reduced, with electronegative maximal combined rod-cone responses and delayed cone-responses with normal amplitudes. Melanoma-associated retinopathy was suspected. Extensive dermatological and internal evaluation eventually revealed an oat-cell carcinoma in the right lung. The patient died of pneumonia 2 years after presentation.

Cancer-associated retinopathy in patients with breast carcinoma

Introduction:

Cancer-associated retinopathy (CAR) is a paraneoplastic neurological syndrome resulting in progressive loss of vision and clinical signs of retinal degeneration. It is associated with various types of cancer and is also considered to be an autoimmune disorder that involves cross-reaction between autoantibodies and retinal proteins. The aim of this study was to establish whether immunoreactivity to retinal antigens (RAs) observed in patients with breast cancer is accompanied by any visual impairments.

Materials and Methods:

Sera of 295 patients with diagnosed breast cancer were screened for the presence of anti-RAs antibodies using immunoblotting. Cellular immunoreactivity to RAs present in retinal extracts and to purified recoverin and arrestin was determined by means of a lymphocyte proliferation assay. Six patients with high-titer antibodies to RAs then underwent ophthalmic and neurological examinations.

Results:

Four serum samples contained high-titer antibodies to a 46-kDa protein, most probably retinal α-enolase, three had antibodies to a 48-kDa protein identified as retinal arrestin, while 56-, 43-, 41-, and 34-kDa antigens were recognized only by one serum sample each. Moreover, weak cellular response to all the RAs tested was observed in one patient and another patient responded only to retinal extract. Two of the examined patients displayed symptoms of CAR.

Conclusions:

Immunoreactivity to RAs in patients with breast cancer may also be present in cases without clinical signs of CAR.

Surveillance of the eye and vision in clinical trials of CP-675,206 for metastatic melanoma

PURPOSE

To determine the ocular safety of CP-675,206 (Pfizer, New York, New York, USA), a fully human anti-cytotoxic T lymphocyte-associated antigen 4 monoclonal antibody in clinical trials of immunotherapy of metastatic melanoma.

DESIGN

Prospective, nonrandomized study of the eye and vision in phase I/II clinical trials of CP-675,206 in metastatic melanoma conducted at the University of California, Los Angeles.

METHODS

Patients with regional or distant metastatic melanoma were enrolled in phase I/II clinical trials evaluating the safety and antitumor efficacy of CP-675,206 alone or in combination with melanoma antigen peptide-pulsed dendritic cell vaccines. Ophthalmic evaluation was performed at the onset of CP-675,206 immunotherapy (baseline evaluation), two months or more after the onset of CP-675,206 immunotherapy (end-study evaluation), and at two- to three-month intervals thereafter in patients who continued to receive CP-675,206 immunotherapy (poststudy evaluation). Baseline and end-study evaluations included comprehensive ophthalmic examination, psychophysical and electrophysiologic visual function assessment, fundus photography, fluorescein angiography, and visual function assessment.

RESULTS

Twenty patients with metastatic melanoma arising from the skin, mucosa, eye, or unknown site were evaluated. Systemic toxicity attributed to CP-675,206 included dermatologic manifestations, diarrhea, and autoimmune hepatitis with panhypopituitarism. A subset of patients receiving CP-675,206 demonstrated antitumor efficacy with partial response or complete response of metastatic melanoma. Comparison of ophthalmic baseline with end-study evaluations in all 20 patients and limited-term poststudy evaluations showed no adverse effect of CP-675,206 immunotherapy on the eye or vision.

CONCLUSIONS

In this study, CP-675,206 immunotherapy for metastatic melanoma did not adversely affect the eye or vision.

Paraneoplastic neurological syndromes

Paraneoplastic neurological syndromes (PNS) can be defined as remote effects of cancer that are not caused by the tumor and its metastasis, or by infection, ischemia or metabolic disruptions. PNS are rare, affecting less than 1/10,000 patients with cancer. Only the Lambert-Eaton myasthenic syndrome is relatively frequent, occurring in about 1% of patients with small cell lung cancer. PNS can affect any part of the central and peripheral nervous system, the neuromuscular junction, and muscle. They can be isolated or occur in association. In most patients, the neurological disorder develops before the cancer becomes clinically overt and the patient is referred to the neurologist who has the charge of identifying a neurological disorder as paraneoplastic. PNS are usually severely disabling. The most common PNS are Lambert-Eaton myasthenic syndrome (LEMS), subacute cerebellar ataxia, limbic encephalitis (LE), opsoclonus-myoclonus (OM), retinopathies (cancer-associated retinopathy (CAR) and melanoma-associated retinopathy (MAR), Stiff-Person syndrome (SPS), chronic gastrointestinal pseudoobstruction (CGP), sensory neuronopathy (SSN), encephalomyelitis (EM) and dermatomyositis. PNS are caused by autoimmune processes triggered by the cancer and directed against antigens common to both the cancer and the nervous system, designated as onconeural antigens. Due to their high specificity (> 90%), the best way to diagnose a neurological disorder as paraneoplastic is to identify one of the well-characterized anti-onconeural protein antibodies in the patient's serum. In addition, as these antibodies are associated with a restricted range of cancers, they can guide the search for the underlying tumor at a stage when it is frequently not clinically overt. This is a critical point as, to date, the best way to stabilize PNS is to treat the cancer as soon as possible. Unfortunately, about one-third of patients do not have detectable antibodies and 5% to 10% have an atypical antibody that is not well-characterized. As PNS are believed to be immune-mediated, suppression of the immune response represents another treatment approach.

Paraneoplastic syndromes in patients with primary head and neck cancer

Paraneoplastic syndromes represent the clinical manifestations of the indirect and remote effects produced by tumor metabolites or other products. The clinical spectrum of the various paraneoplastic syndromes related to primary malignancies of the head and neck region is presented. A review of the literature on paraneoplastic syndromes in patients with primary head and neck cancer was carried out. Paraneoplastic syndromes related to primary malignancies of the head and neck region can be categorized as: endocrine, cutaneous or dermatologic, hematologic, neurologic, osteoarticular or rheumatologic, ocular syndromes. Sometimes, paraneoplastic syndromes can be more serious than the consequences of the primary tumor itself and can precede, follow or be concurrent to the diagnosis of a malignancy; moreover, they can dominate the clinical picture and thus lead to errors with respect to the origin and type of the primary tumor. Physicians who deal with cancer-associated syndromes should be able to differentiate the paraneoplastic syndromes from the benign disorders that mimic them. Patients with a suspected paraneoplastic disorder should undergo a complete panel of laboratory studies, in addition to imaging studies and endoscopy. Identification of paraneoplastic syndromes allow the clinician to make an early diagnosis and to provide adequate treatment of tumors, with a favorable oncologic outcome and improved life expectancy for the patient. These syndromes can follow the clinical course of the tumor and thus be useful for monitoring its evolution.

Recoverin as a cancer-retina antigen

In photoreceptor cells the Ca(2+) -binding protein recoverin controls phosphorylation of the visual receptor rhodopsin by inhibiting rhodopsin kinase (GRK-1). It can also serve as a paraneoplastic antigen in the development of retinal degeneration in some patients with cancer. The aberrant expression of recoverin in cancer cells and the presence of autoantibodies against recoverin are essential for the occurrence of cancer-associated retinopathy, which finally results in the apoptosis of photoreceptor cells. Noteworthy in cancer patients, the aberrant recoverin expression and the appearance of autoantibodies against recoverin are more frequent than paraneoplastic syndromes. We suggest the term "cancer-retina antigens" for this kind of proteins like recoverin that are solely expressed in retina and tumor tissues and evoke antibodies and/or T cells in patients with cancer. The rare development of a paraneoplastic syndrome is possibly caused by this immune response and probably depends on further events allowing to overcome the blood-retina barrier and the immune privileged status of the retina. It is still unknown whether aberrantly expressed recoverin could have a specific function in cancer cells, though it is suggested that it can be functionally associated with G-protein-coupled receptor kinases. This paper reviews the present knowledge on paraneoplastic syndromes associated with the aberrant expression of recoverin. A possible application of recoverin as a potential target for immunotherapy of cancer is discussed.

Mitofilin and titin as target antigens in melanoma-associated retinopathy

Melanoma-associated retinopathy (MAR) is a rare paraneoplastic syndrome in patients with melanoma. Since the onset of MAR symptoms is often associated with tumor progression or recrudescence of metastases, MAR-related symptoms are prognostic relevant. The pathomechanism underlying MAR is supposed to result from antibody production against yet unknown melanoma-associated antigens that are also expressed in retinal tissue, leading to the destruction of retinal cells and resulting in defective signal transduction. Only a 35 kDa protein in Müller glial cells, a 22 kDa neuronal antigen and retinal transducin have been identified as MAR-associated antigens to date. To identify additional antigens potentially involved in the pathogenesis of MAR, we screened a retina cDNA phage library for reactivity with antibodies in the sera from 9 patients with MAR or subclinical MAR using the serological analysis of recombinantly expressed clones (SEREX) approach. Six sera from melanoma patients without evidence of MAR and 10 sera from healthy donors served as controls. Mitofilin and titin were identified as antigens against which antibodies were found exclusively in sera of MAR patients, but not in the sera of MM patients without MAR or healthy donors. This is the first study to demonstrate that titin is highly expressed from retinal tissue and melanoma. The fact that none of the MAR-associated antigens detected to date by their capacity to elicit a humoral immune response is located on the cell surface questions a major pathogenetic role of the respective antibodies and suggests that cellular, rather than humoral mechanisms are operative in the primary immune attack against the retina in MAR.

Frequency of colour vision deficiencies in melanoma patients: results of a prospective comparative screening study with the Farnsworth panel D 15 test including 300 melanoma patients and 100 healthy controls

Patients with melanoma may experience a variety of different vision symptoms, in part associated with melanoma-associated retinopathy. For several melanoma patients with or without melanoma-associated retinopathy, colour vision deficiencies, especially involving the tritan system, have been reported. The frequency of colour vision deficiencies in a larger cohort of melanoma patients has not yet been investigated. The aim of this study was to investigate the frequency of colour vision deficiencies in melanoma patients subject to stage of disease, prognostic factors such as tumour thickness or Clark level, S100-beta and predisposing diseases that may have an impact on colour vision (hypertension, diabetes mellitus, glaucoma or cataract). Three hundred melanoma patients in different tumour stages and 100 healthy age-matched and sex-matched controls were examined with the saturated Farnsworth panel D 15 test. Seventy out of 300 (23.3%) melanoma patients and 12/100 (12%) controls showed pathologic results in colour testing. This discrepancy was significant (P < 0.016; odds ratio = 2.23, 95% confidence interval 1.15-4.32). Increasing age was identified as a highly significant (P = 0.0005) risk factor for blue vision deficiency. Adjusting for the age and predisposing diseases, we could show that melanoma was associated with the risk of blue vision deficiency. The frequency of blue vision deficiency in 52/260 melanoma patients without predisposing diseases (20%) compared with 4/78 controls without predisposing diseases (5.1%) differed significantly (odds ratio 4.441; confidence interval 1.54-12.62; P < 0.004). In 260 melanoma patients without predisposing diseases, blue vision deficiency, as graded on a 6-point scale, showed a weak positive correlation (Spearman) with tumour stage (r = 0.147; P < 0.01), tumour thickness (r = 0.10; P = 0.0035), Clark level (r = 0.12; P = 0.04) and a weak negative correlation with time since initial diagnosis (r = -0.11; P = 0.0455). Blue vision deficiency is associated with melanoma, but is only weakly related to stage of disease. Although we saw a positive correlation with well-known prognostic markers, such as tumour thickness and Clark level, blue vision deficiency as assessed by the Farnsworth panel D 15 test in general is inappropriate as a marker of tumour progression. For the use of blue vision deficiency in melanoma patients without predisposing diseases, a diligent test performance and interpretation is very important.

Clinical disorders affecting mesopic vision

Vision in the mesopic range is affected by a number of inherited and acquired clinical disorders. We review these conditions and summarize the historical background, describing the clinical characteristics alongside the genetic basis and molecular biological mechanisms giving rise to rod and cone dysfunction relevant to twilight vision. The current diagnostic gold standards for each disease are discussed and curative and symptomatic treatment strategies are summarized.

Autoantibodies to p75/LEDGF, a cell survival factor, found in patients with atypical retinal degeneration

We have identified a group of patients with an atypical retinal degeneration having anti-retinal autoantibodies in their sera. This select population is characterized by a progressively severe loss of vision associated with a decrease in photoreceptor function, abnormal pigmentation of the retinal pigment epithelium and a negative family history of retinal dystrophy. Immunohistochemical analysis on mouse retinal tissues with sera from this group of patients demonstrated high titers of anti-retinal antibodies (320 to 1,280). Anti-retinal reactivity at these levels was not detected in sera from normal individuals, or from patients with uveitis or known genetic retinal degenerations. One antigen that was identified from a retina cDNA library with sera from a patient with atypical retinal degeneration was lens epithelium-derived growth factor (LEDGF). Western blot analysis revealed that sera from all three patients demonstrated reactivity to p75/LEDGF, a survival factor that protects cells from oxidative, thermal and UV damage. In conclusion, we have found a novel group of patients with a retinal degeneration of non-paraneoplastic, non-familial origin demonstrating immunoreactivity to an autoantigen, p75/LEDGF, heretofore not associated with this disease. Finally, identification of specific anti-retinal antibodies may have applications in the diagnosis and management of retinal degeneration.

Intravenous immunoglobulin in eye involvement

Ocular inflammation may affect all eye layers: conjunctiva, sclera, uvea, and orbital tissues. The main eye involvement requiring a systemic treatment is uveitis, which represents a heterogeneous group of rare diseases, most of which are sight-threatening. In around 40% of uveitis cases an underlying systemic disease, often of autoimmune origin, can be identified. In autoimmune diseases with intraocular inflammation (IOI), uveitis may be the first clinical manifestation and may represent the most severe sign. Studies in animal models, especially in experimental autoimmune uveitis (EAU), offer the opportunity to investigate the pathogenicity of these disorders. The conventional treatment of IOI includes corticosteroids and immunosuppressive agents, which are efficient in around one-half of the patients; however, their effectiveness is also limited by their iatrogenicity. The effects of intravenous immunoglobulin (IVIg) on ocular inflammation have been investigated in a wide spectrum of autoimmune/systemic diseases. Most publications are case series or open trials. They show favorable results in a subset of indications including mainly ocular cicatricial pemphigoid, Vogt-Koyanagi-Harada syndrome, or birdshot disease. Efficacy results are more debated in other conditions, such as inflammatory demyelinating optic neuritis. In other diseases with IOI (Wegener disease, Behcet's disease, inflammatory myositis), only case reports are available, suggesting that IVIg may be of some interest. These observations support the need for controlled trials to demonstrate the efficacy of IVIg and assess their potential steroid-sparing effect.

Immunotherapy for paraneoplastic neurological disorders

Paraneoplastic disorders may affect any part of the central or peripheral nervous systems. Although relatively uncommon, these disorders are a significant cause of severe neurological disability among cancer patients. Most, if not all, neurological paraneoplastic disorders are believed to be autoimmune diseases in which an antitumour immune response also attacks neurons that express shared neuronal tumour antigens. Affected patients often have one or more circulating antineuronal antibodies, which serve as a diagnostic marker for the paraneoplastic condition, and in some cases are the direct mediators of neuronal injury. The exact immunopathogenesis and relative contributions of humoral or cellular immune effectors for most paraneoplastic syndromes are not well understood. Some patients have a gratifying neurological response to tumour treatment and/or immunotherapy, especially if the diagnosis is made early and treatment is initiated promptly. Unfortunately, many patients are left with severe and permanent neurological deficits despite aggressive treatment. This review summarises the current understanding of the clinical immunology of paraneoplastic disorders, and outlines immunotherapy options and outcomes.

Autoimmune retinopathy with RPE hypersensitivity and 'negative ERG' in X-linked hyper-IgM syndrome

PURPOSE

To report the clinical, electrophysiological, and immunological features of a patient with X-linked hyper-IgM immunodeficiency syndrome type 1 (HIGM1) accompanied by a novel type of autoimmune retinopathy, including retinal pigment epithelium (RPE) hypersensitivity.

METHODS

Comprehensive ophthalmological examinations, electrophysiological function testing, and inquiries into the immunological status of a 13-year-old presenting with subacute loss of vision in association with a molecularly confirmed diagnosis of HIGM1 were performed. The patient was genotyped by a PCR-based sequence tag content mapping strategy to define the genetic defect within the causative X-HIM gene TNFSF5. Since conventional allogenic bone marrow transplantation has been reported to cure HIGM1, a peripheral blood stem-cell transplantation was performed.

RESULTS

(1) The patient's reduced visual acuity included prolonged dark adaptation and visual field constriction. Electrophysiology revealed a 'negative ERG' indicating post-receptoral dysfunction. (2) Initial immunological examination of the patient's serum identified abnormal antibody activity with components of the photoreceptors and the inner nuclear layer. The patient later developed indications of RPE hypersensitivity. A massively reduced light-peak to dark-trough ratio of the EOG slow oscillations (L/D ratio) corresponded to impaired RPE-photoreceptor complex function. (3) Molecular genetic analyses revealed the patient to be nullizygous for the tumor necrosis factor ligand member 5 gene (TNFSF5; CD40LG). A large chromosomal deletion of approximately 27.6-32.3 kb in size was identified in Xq26. (4) The transplant with its associated immunomodulation appeared to worsen rather than improve the patient's condition.

CONCLUSIONS

The fundus appearance and electrophysiological function testing revealed indications of atypical retinal degeneration. However, the clinical course and the serological findings were consistent with those of ocular autoimmunity involving both antiretinal activity and RPE hypersensitivity. In this case, peripheral stem-cell transfusion with its associated chemotherapy failed to benefit the patient's vision; indications of autoimmunity appeared to increase following this treatment.

Update on paraneoplastic syndromes

PURPOSE OF REVIEW

This review discusses the varied clinical spectrum of neurologic paraneoplastic disorders, describes recent advances in our understanding of autoimmunity in these disorders, and outlines a practical clinical approach to patient management.

RECENT FINDINGS

Paraneoplastic disorders may affect any part of the central or peripheral nervous system. Although relatively uncommon, these disorders are a significant cause of severe and permanent neurologic disability. Syndromes such as limbic encephalitis or opsoclonus-myoclonus should always raise suspicion of a paraneoplastic condition, but any paraneoplastic syndrome can also occur in patients without a neoplasm. Most neurologic paraneoplastic disorders are thought to be caused by an autoimmune reaction directed against 'onconeural' antigens expressed by neurons and tumor cells. Some syndromes such as Lambert-Eaton myasthenic syndrome and neuromyotonia are clearly mediated by autoantibodies. Much less is known about the immunopathogenesis of syndromes that affect the central nervous system, although a growing body of evidence implicates cellular immune effectors in causing neuronal injury. Many patients have circulating antineuronal antibodies, which can be useful in identifying a neurologic disorder as paraneoplastic and in finding the associated neoplasm. Early diagnosis of the neurologic disorder and prompt initiation of tumor treatment probably increase the likelihood of neurologic improvement.

SUMMARY

Neurologists must be able to recognize the clinical manifestations of neurologic paraneoplastic disorders, and to distinguish them from other causes of neurologic dysfunction in cancer patients. Early diagnosis of paraneoplastic syndromes maximizes the likelihood of a favorable oncologic and neurologic outcome.

Incidence of antiretinal antibodies in melanoma: screening of 77 serum samples from 51 patients with American Joint Committee on Cancer stage I-IV

BACKGROUND

Patients with melanoma-associated retinopathy (MAR) experience different visual symptoms caused by the production of antitumoral antibodies that cross-react with retinal epitopes. Immunofluorescence assays of serum from patients with MAR on sectioned monkey or human retina characteristically reveal antibody activity located within the inner nuclear layer, with a focus of activity upon the membranes of bipolar cells.

OBJECTIVES

We inquired into the association with disease of this serological abnormality by evaluating sera from patients with melanoma with no MAR-like signs or symptoms.

METHODS

Groups of patients were selected with different stages of melanoma (American Joint Committee on Cancer stages I-IV). Seventy-seven serum samples from 51 patients with melanoma were examined by indirect immunohistochemical assay on sections of human retina.

RESULTS

Of the 77 serum samples, 53 were found to contain antibodies reactive with various components of retina. Eight were from 17 sera from patients in stage I or II, 14 were from 23 sera from patients in stage III, and 31 were from 37 sera from patients in stage IV. Statistical analysis revealed a correlation between antibody activity and the stage of disease, with a higher percentage of antibody activity in advanced stages (P = 0.002).

CONCLUSIONS

The presence of antiretinal antibodies in patients with melanoma without ocular symptoms appears to be more common than previously suspected. Antibody activity similar to that ascribed to the MAR syndrome appears in some patients with melanoma who have no MAR-like retinopathy. Follow-up studies will determine if patients with antiretinal antibodies go on to develop MAR and if staining intensity and staining patterns change over the course of the disease.

SEREX identification of new tumor antigens linked to melanoma-associated retinopathy

Metastatic melanoma still has a very poor prognosis since it withstands conventional therapies like surgery or chemotherapy. A paraneoplastic autoimmune manifestation of this disease is melanoma-associated retinopathy (MAR). MAR has been associated with prolonged survival and may be an early marker of tumor progression. By screening a retina and a melanoma cDNA phage library by SEREX using sera of patients suffering from melanoma and, in some cases, clinical symptoms of MAR, we identified 20 new antigens (HD-MM-28-47), of which 14 clones had high homology to well-known genes. Six of these genes had previously been associated with retina: rhodopsin, visual arrestin, MEK1, SRPX, BBS1 and galectin-3. Individual clones were recognized by up to 43% of patients' sera, while sera of healthy volunteers were negative except in 2 cases. The expression profile of the antigens identified on the basis of homologous EST database entries in healthy tissues was ubiquitous to differential. Using RT-PCR, we found frequent expression of preselected antigens in melanoma cell lines. For rhodopsin, this could be quantified by quantitative PCR. Retinal proteins were recognized by serum antibodies of melanoma patients but not healthy controls. The role of these antigens in MAR awaits further investigation. (Supplementary material for this article can be found on the International Journal of Cancer website at http://www.interscience.wiley.com/jpages/0020-7136/suppmat/index.html.)

Advances in paraneoplastic neurological syndromes

PURPOSE OF REVIEW

To describe specificities and new advances in paraneoplastic neurologic syndromes (PNSs).

RECENT FINDINGS

Paraneoplastic neurologic syndromes are defined as neurologic syndromes of unknown cause that often antedate the diagnosis of an underlying, usually not clinically evident, cancer. In the last 2 decades, the discovery that many PNSs are associated with antibodies against neural antigens expressed by the tumor has suggested that some PNSs are immune-mediated. PNSs are rare and occur in less than 1% of patients with cancer. However, the diagnosis and treatment are important because the disability caused by the PNS is often severe, and the correct diagnosis usually leads to the discover of a small tumor with high chances of being cured.

SUMMARY

There is increasing recognition of an extensive variety of PNSs and of several paraneoplastic antibodies as clinical markers of these disorders. Basic immunologic studies support the pathogenic role of some of these antibodies, and basic molecular studies support the role of some antigens in neuronal degeneration and tumoral growth.

Paraneoplastic retinopathy/ optic neuropathy

Paraneoplastic retinopathy and paraneoplastic optic neuropathy comprise a heterogeneous group of ocular syndromes associated with various clinical symptoms and multiple circulating antiretinal antibodies. Current evidence supports an underlying autoimmune mediated process, which is the rationale for the provision of immunosuppressive therapy in addition to antitumor treatment. There are no controlled clinical trials that address the treatment of paraneoplastic retinopathy and/or optic neuropathy. Management decisions must be based on a relatively small number of case reports. There have been no reports of spontaneous visual improvement in these disorders. Therefore, any improvement after treatment is attributable to the therapeutic intervention. With the exception of the paraneoplastic optic neuropathy patient group, most patients show little or no response to immunosuppressive therapy, and only a small percentage of patients have dramatic improvement. However, modest improvements in visual function can improve patient quality of life and functional independence. Prompt diagnosis and initiation of therapy before significant visual loss is seen seems to be a critical factor in treatment success. An increase in serial autoantibody titers may serve as a marker of disease activity and allow initiation of therapeutic interventions before symptomatic visual decline.

Surveillance of the eye and vision in a clinical trial of MART1-transformed dendritic cells for metastatic melanoma

PURPOSE

To report the protocol for surveillance of the eye and vision in a clinical trial of MART1-transduced dendritic cells for metastatic melanoma.

METHODS

In a phase I/II clinical trial of dendritic cell-based genetic immunotherapy for metastatic cutaneous melanoma, ophthalmic evaluation is performed prior to immunization (Baseline Evaluation), 56+/-7 days after first vaccination (mid-study evaluation), when dendritic cell injections are complete 112+/-7 days after first vaccination (end-study evaluation) and 168+/-7 days after first vaccination (post-study evaluation).

RESULTS

The protocol for baseline, mid-study and end-study evaluations of the eye and vision includes ophthalmic history, comprehensive ophthalmic examination, psychophysical and electrophysiological visual function assessment, fundus photography and fluorescein angiography. Post-study evaluation consists of the 25-item visual functioning questionnaire augmented to elicit autoimmune manifestation with complete ophthalmic evaluation if vision-related symptoms or abnormalities are noted during or after the vaccination.

CONCLUSION

Limited adverse effects on the eye and vision have been reported in melanoma immunotherapy trials, although this novel mode of therapy has the potential to induce melanoma paraneoplastic syndromes known to severely impair vision. Therefore, surveillance of the eye and vision should be considered in melanoma immunotherapy trials.

Neuro-ophthalmology and paraneoplastic syndromes

PURPOSE OF REVIEW

To describe the neuro-ophthalmological manifestations of paraneoplastic syndromes and their immunological associations.

RECENT FINDINGS

Neuro-ophthalmological signs and symptoms are usually present in paraneoplastic syndromes of the central nervous system. Unlike opsoclonus, less characteristic eye movement abnormalities are difficult to recognize as presenting symptoms of paraneoplastic syndromes. In this setting, the detection of several antibodies, including anti-Hu, Yo, Ma2, Ri, Tr, CV2/CRMP5 or voltage-gated calcium channel antibodies may help to establish that the neuro-ophthalmological disorder is paraneoplastic. Among the recently characterized antibodies, those against the Ma proteins often associate with brainstem encephalitis and vertical gaze paralysis. A small subset of patients with opsoclonus and ataxia harbor anti-Ri antibodies. In other patients, there is preliminary evidence that the autoantigens of opsoclonus reside in the postsynaptic density, but no dominant antibody marker has been identified. Uveitis and optic neuritis are rare accompaniments of paraneoplastic encephalomyelitis; some of these patients harbor anti-CV2/CRMP5 in association with other antibodies. Studies on paraneoplastic retinopathy indicate that immunity to retinal proteins other than recoverin can result in a similar syndrome to that associated with recoverin antibodies, and that melanoma-associated retinopathy may associate with several retinal antibodies.

SUMMARY

There is increasing recognition of an extensive variety of neuro-ophthalmological abnormalities as manifestations of paraneoplastic syndromes and of several antineuronal antibodies as clinical markers of these disorders. Basic immunological studies support the pathogenic role of some of these antibodies, and are elucidating the pathogenic mechanisms that underlie these and other antibody-associated paraneoplastic syndromes.

Retinitis pigmentosa: understanding the clinical presentation, mechanisms and treatment options

Retinitis pigmentosa (RP) is a leading cause of human blindness due to degeneration of retinal photoreceptor cells. Causes of retinal degeneration include defects in the visual pigment, defects in the proteins important for photoreceptor function or in enzymes involved in initiating visual transduction. Despite the diversity of genetic mutations identified in inherited forms of retinal dystrophy, there is a common end result of photoreceptor death and functional blindness. In this review, pertinent anatomical and physiological pathways involved in RP and the underlying genetic mutations are outlined, including a discussion on the inheritance patterns revealed by advances in molecular biological techniques. Characteristics of progression rates of visual field loss and current management options will provide useful clinical guidelines for the management of patients with RP.

Autoantibodies against retinal proteins in paraneoplastic and autoimmune retinopathy

Background

Autoimmune retinal degeneration may occur in patients who present with sudden or, less commonly, subacute loss of vision of retinal origin, associated with an abnormal ERG, through the action of autoantibodies against retinal proteins. Often the patients are initially diagnosed with or suspected of having a paraneoplastic retinopathy (PR), such as cancer-associated retinopathy (CAR). However, there is limited information on the occurrence, the specificity of autoantibodies in these patients, and their association with clinical symptoms.

Methods

Sera were obtained from 193 retinopathy patients who presented with clinical symptoms resembling PR or autoimmune retinopathy (AR), including sudden painless loss of vision, typically associated with visual field defects and photopsias, and abnormal rod and/or cone responses on the electroretinogram (ERG). Sera were tested for the presence of anti-retinal autoantibodies by Western blot analysis using proteins extracted from human retina and by immunohistochemistry. Autoantibody titers against recoverin and enolase were measured by ELISA.

Results

We identified a higher prevalence of anti-retinal autoantibodies in retinopathy patients. Ninety-one patients' sera (47.1%) showed autoantibodies of various specificities with a higher incidence of antibodies present in retinopathy patients diagnosed with cancer (33/52; 63.5%; p = 0.009) than in retinopathy patients without cancer (58/141; 41.1%). The average age of PR patients was 62.0 years, and that of AR patients was 55.9 years. Autoantibodies against recoverin (p23) were only present in the sera of PR patients, autoantibodies against unknown p35 were more common in patients with AR, while anti-enolase (anti-p46) autoantibodies were nearly equally distributed in the sera of patients with PR and those with AR. In the seropositive patients, the autoantibodies persisted over a long period of time – from months to years. A rebound in anti-recoverin autoantibody titer was found to be associated with exacerbations in visual symptoms but not in the recurrence of cancer. When compared to sera from healthy subjects, autoantibodies against retinal proteins from both groups of patients were cytotoxic to retinal cells, indicating their pathogenic potential.

Conclusions

These studies showed that patients with sudden or subacute, unexplained loss of vision of retinal origin have anti-retinal antibodies in a broad range of specificity and indicate the need for autoantibody screening. Follow-up tests of antibody levels may be useful as a biomarker of disease activity associated with worsening of vision. Moreover, the heterogeneity in autoantibody specificity may explain the variation and complexity of clinical symptoms in retinopathy patients.

Neurologic paraneoplastic syndromes

Paraneoplastic disorders can affect any part of the central or peripheral nervous system. Although relatively uncommon, these disorders are a significant cause of severe neurologic disability among cancer patients. Many paraneoplastic disorders are believed to be caused by an autoimmune response directed against shared neural tumor antigens. This article summarizes the clinical features, possible autoimmune pathophysiology, and management issues for patients with paraneoplastic disorders.

Paraneoplastic syndromes associated with visual loss

PURPOSE OF REVIEW

The recent literature was reviewed to analyze the developments in the diagnosis, pathogenesis, and immunology of this group of paraneoplastic syndromes. Clinical features and pathologic findings are summarized.

RECENT FINDINGS

The mechanism of cell death in cancer-associated retinopathy appears to occur through apoptotic pathways. Caspase inhibitors and a calcium antagonist have been used in animal models to block or suppress the effect of the antirecoverin antibodies on the retina with significant response. These agents are possible treatment options for cancer-associated retinopathy. Aberrant expression of recoverin by tumor cells does not necessarily induce antirecoverin antibodies and cancer-associated retinopathy. Many tumors, not just those producing the clinical picture of cancer-associated retinopathy, have been shown to express recoverin. Recoverin appears to play a functional role in tumor cells, and antirecoverin antibodies may have tumor-suppressing effects. Further research into this area may help design epitope-based immunotherapy for patients with recoverin-expressing tumors. Further evidence has emerged to support the initial observation that depolarizing bipolar cells are the likely retinal target in melanoma-associated retinopathy. Intravitreal injection of melanoma-associated retinopathy serum produced electroretinogram changes in animals very similar to the clinical findings in humans. Many new antibodies and antigens had been discovered to be linked to various paraneoplastic syndromes. Anti-collapsing response-mediating protein-5 is likely to be an important one; it was found to be the second most common autoantibody related to paraneoplastic neurologic syndromes.

SUMMARY

Further research into the functional role of recoverin in cancer cells may advance our understanding in cancer immunology. Immunotherapy may be possible if a specific epitope of recoverin can be found to contain the antigenic site for antitumor antibodies and not cross-react with retinal antigens. Research into the pathogenesis of the other paraneoplastic syndromes is required for a better understanding and treatment of these rare conditions. The missing link between primary cutaneous melanoma and uveal melanocytes still eludes investigators in bilateral diffuse uveal melanocytic proliferation. The discovery of the missing link may provide us with some understanding of the development of uveal melanoma.