Paraneoplastic syndromes (PNS) associated with Merkel cell carcinoma (MCC): A case series of 8 patients highlighting different clinical manifestations

Neurological autoimmunity in patients with non-pulmonary neuroendocrine neoplasms: clinical manifestations and neural autoantibody profiles

BACKGROUND AND PURPOSE

Paraneoplastic neurological autoimmunity is well described with small-cell lung cancer, but information is limited for other neuroendocrine neoplasms (NENs).

METHODS

Adult patients with histopathologically confirmed non-pulmonary NENs, neurological autoimmunity within 5 years of NEN diagnosis, and neural antibody testing performed at the Mayo Clinic Neuroimmunology Laboratory (January 2008 to March 2023) were retrospectively identified. Control sera were available from patients with NENs without neurological autoimmunity (116).

RESULTS

Thirty-four patients were identified (median age 68 years, range 31-87). The most common primary tumor sites were pancreas (nine), skin (Merkel cell, eight), small bowel/duodenum (seven), and unknown (seven). Five patients received immune checkpoint inhibitor (ICI) therapy before symptom onset; symptoms preceded cancer diagnosis in 62.1% of non-ICI-treated patients. The most frequent neurological phenotypes (non-ICI-treated) were movement disorders (12; cerebellar ataxia in 10), dysautonomia (six), peripheral neuropathy (eight), encephalitis (four), and neuromuscular junction disorders (four). Neural antibodies were detected in 55.9% of patients studied (most common specificities: P/Q-type voltage-gated calcium channel [seven], muscle-type acetylcholine receptor [three], anti-neuronal nuclear antibody type 1 [three], and neuronal intermediate filaments [two]), but in only 6.9% of controls. Amongst patients receiving cancer or immunosuppressive therapy, 51.6% had partial or complete recovery. Outcomes were unfavorable in 48.3% (non-ICI-treated) and neural autoantibody positivity was associated with poor neurological outcome.

DISCUSSION

Neurological autoimmunity associated with non-pulmonary NENs is often multifocal and can be treatment responsive, underscoring the importance of rapid recognition and early treatment.

Paraneoplastic neurologic manifestations of neuroendocrine tumors

Neuroendocrine neoplasms (NENs) are a heterogeneous group of tumors arising from the transformation of neuroendocrine cells in several organs, most notably the gastro-entero-pancreatic system and respiratory tract. The classification was recently revised in the 5th Edition of the WHO Classification of Endocrine and Neuroendocrine Tumors. NENs can rarely spread to the central or peripheral nervous systems. Neurologic involvement is determined by the rare development of paraneoplastic syndromes, which are remote effects of cancer. Mechanisms depend on immunologic response to a tumor, leading to the immune attack on the nervous system or the production of biologically active ("functioning") substances, which can determine humoral (endocrine) effects with neurologic manifestations. Paraneoplastic neurologic syndromes (PNS) are immunologically mediated and frequently detected in small cell lung cancer but rarely seen in other forms of NEN. PNS and Merkel cell carcinoma is increasingly reported, especially with Lambert Eaton myasthenic syndrome. Endocrine manifestations are found in a wide spectrum of NENs. They can develop at any stage of the diseases and determine neurologic manifestations. Patient outcomes are influenced by tumor prognosis, neurologic complications, and the severity of endocrine effects.

Nivolumab-induced sensory ganglionopathy

INTRODUCTION

Nivolumab is s a human monoclonal antibody. Due to its widespread use in many cancers, including Merkel cell carcinoma, adverse reactions associated with nivolumab, such as neuropathies, endocrinopathies, gastrointestinal problems, and skin toxicities have been increasing. Sensory ganlionopathy is rarely observed in these patients.

CASE DESCRIPTION

We present a 63-year-old male with a medical history of Merkel cell carcinoma that recurred two times in the inguinal region. After undergoing surgery with adjuvant radiotherapy, a second surgery was performed. The patient suffered from tingling in all four limbs plus difficulty in walking after initiation of the third dose of nivolumab.

MANAGEMENT AND OUTCOME

After 1 month of 1 mg/kg/day methylprednisolone treatment, he showed significant improvement. Subsequently, the systemic corticosteroid regimen was tapered to 5 mg every other day. The treatment resulted in significant improvement in all extremities.

DISCUSSION

Sensory ganlionopathy can be seen as a side effect of an immune checkpoint inhibitor, even though it is very extraordinary. This is the case in the literature to develop sensory ganlionopathy due to nivolumab. We believe that patients using nivolumab may develop sensory ganlionopathy and management should be taken on this point.

Ectopic Cushing's syndrome in a patient with metastatic Merkel cell carcinoma: A case report

BACKGROUND

Ectopic Cushing syndrome (ECS) is a rare condition commonly associated with neuroendocrine tumors (NET), mainly bronchial carcinoids. The association of paraneoplastic syndrome with Merkle cell carcinoma (MCC) is limited to individual case reports.

CASE SUMMARY

In this article we report an unusual and striking presentation of ECS in a patient with known metastatic MCC. An elderly patient presented with new onset severe hypertension, hyperglycemia and hypokalemia, muscle wasting, and peripheral edema. A diagnosis of adrenocorticotropic hormone dependent, non-pituitary, Cushing syndrome was established. Medical therapy inhibiting adrenal function was promptly started but unfortunately the patient survived only a few days after diagnosis.

CONCLUSION

The occurrence of an aggressive form of ECS in patients with NET should be recognized as an ominous event. To our knowledge, the association of this complication in a patient with MCC had not been reported.

Paraneoplastic Syndromes in Patients with Keratinocyte Skin Cancer

Simple Summary

The aim of the present review is to compile and evaluate the literature data on paraneoplastic syndromes (PNS) associated with keratinocyte skin cancer (KSC). Forty relevant entries were assembled, reporting a total of 41 PNS cases associated with a KSC (34 male). No review paper compiling this topic was found. Six distinct PNS entities were identified, and malignancy associated hypercalcemia (MAH; 78%), anemia (10%) and Bazex syndrome (5%) were the most frequently reported among them. 85% of the PNS were reported in association with SCC, 10% with BCC, and the rest with adnexal tumors. The median age of the patients at the time of PNS diagnosis was 58 years (range: five–83 years). KSC predisposing conditions, as scars (22%) or hidradenitis suppurativa (20%), were reported in >70% of the PNS cases. In conclusion, PNS are rarely reported in association with KSC, possibly reflecting a limited capacity of KSC to provoke overt PNS.

Abstract

A variety of well-characterized cutaneous paraneoplastic syndromes (PNS) are diagnosed during internal malignancies; however, the spectrum of keratinocyte skin neoplasms (KSC) related to PNS is still obscure. The aim of the present review is to compile and evaluate the literature data on PNS associated with a keratinocyte skin neoplasm (KSC). Employing Pubmed, MEDLINE was searched for KSC-associated PNS reports. Forty relevant entries were assembled, reporting a total of 41 PNS cases associated with a KSC (34 male). No review paper compiling this topic was found. Six distinct PNS entities were identified, and malignancy associated hypercalcemia (MAH; 78%), anemia (10%) and Bazex syndrome (5%) were the most frequently reported among them. 85% of the PNS were reported in association with SCC, 10% with BCC, and the rest with adnexal tumors. The median age of the patients at the time of PNS diagnosis was 58 years (range: five–83 years). In most cases the PNS was diagnosed either concurrently or after the KSC diagnosis. KSC predisposing conditions, as scars (22%) or hidradenitis suppurativa (20%), were reported in >70% of the PNS cases. Most PNS resolved after KSC treatment. In conclusion, PNS of a rather limited spectrum of entities are reported in association with KSC. They also seem to be rare, possibly reflecting a limited capacity of KSC to provoke overt PNS.

Regionally Metastatic Merkel Cell Carcinoma Associated with Paraneoplastic Anti-N-methyl-D-aspartate Receptor Encephalitis

Merkel cell carcinoma (MCC) is a rare and aggressive cutaneous neuroendocrine cancer with a high risk of recurrence and metastasis. MCC is generally associated with advanced age, fair skin, sun exposure, immunosuppression, and in the majority of cases, the Merkel cell polyomavirus. Neuroendocrine malignancies are associated with a variety of paraneoplastic neurological syndromes (PNS), characterized as autoimmune responses to malignancy-associated expression of neural antigens. Our literature review underscores previous case reports of MCC-associated PNS with voltage-gated calcium channel (VGCC) and anti-Hu (or ANNA-1) autoantibodies. We present the case of a 59-year-old male with regionally metastatic Merkel cell carcinoma complicated by the paraneoplastic manifestation of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. His primary lower neck subcutaneous MCC and metastasis were initially treated with surgery. Additional recurrent lymph node metastases were successfully treated with definitive intensity-modulated radiation therapy. His PNS improved with rituximab therapy. Although rare, this case highlights that in the setting of seizures and prominent psychiatric symptoms accompanying an MCC diagnosis, evaluation for autoimmune paraneoplastic encephalitis is warranted. Awareness and detection of preexisting PNS are crucial in the era of immune checkpoint inhibitors (ICI) for advanced MCC, where treatment with ICI has the potential to exacerbate preexisting autoimmune PNS and lead to worsened or even lethal neurologic immune-related adverse events (nirAEs).

An autoimmune-based, paraneoplastic neurologic syndrome following checkpoint inhibition and concurrent radiotherapy for merkel cell carcinoma: case report

PURPOSE

Merkel cell carcinoma is highly sensitive to both radiation and immunotherapy. Moreover, concurrent radioimmunotherapy may capitalize on anti-tumor immune activity and improve Merkel cell treatment response, although an enhanced immune system may cross-react with native tissues and lead to significant sequelae.

METHODS

Here we present a case study of a patient with metastatic Merkel cell carcinoma treated with radiotherapy concurrent with pembrolizumab.

RESULTS

After radioimmunotherapy, the patient developed sensory neuropathy, visual hallucinations, and mixed motor neuron findings. Neurologic dysfunction progressed to profound gastrointestinal dysmotility necessitating parenteral nutrition and intubation with eventual expiration.

CONCLUSION

This case represents a unique autoimmune paraneoplastic neurologic syndrome, likely specific to neuroendocrine tumors and motivated by concurrent radioimmunotherapy. Recognition of the potential role of radioimmunotherapy may provide an advantage in anticipating these severe sequelae.

Driving innovation for rare skin cancers: utilizing common tumours and machine learning to predict immune checkpoint inhibitor response

Metastatic Merkel cell carcinoma (MCC) and cutaneous squamous cell carcinoma (cSCC) are rare and both show impressive responses to immune checkpoint inhibitor treatment. However, at least 40% of patients do not respond to these expensive and potentially toxic drugs. Development of predictive biomarkers of response and rational, effective combination treatment strategies in these rare, often frail patient populations is challenging. This review discusses the pathophysiology and treatment of MCC and cSCC, with a particular focus on potential biomarkers of response to immunotherapy, and discusses how transfer learning using big data collected from patients with common tumours can be used in combination with deep phenotyping of rare tumours to develop predictive biomarkers and elucidate novel treatment targets.

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Metastatic Merkel cell carcinoma and cutaneous squamous cell carcinoma are rare tumours.

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Immunotherapy gives impressive responses but most patients do not survive long term.

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Small patient numbers prevent extensive biomarker research in clinical trials.

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Pooled data from common and rare tumours can be used to train neural networks.

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In rare cancers, neural networks can help identify biomarkers and novel treatment targets.

Paraneoplastic neuronal intermediate filament autoimmunity

Objective

To describe paraneoplastic neuronal intermediate filament (NIF) autoimmunity.

Methods

Archived patient and control serum and CSF specimens were evaluated by tissue-based indirect immunofluorescence assay (IFA). Autoantigens were identified by Western blot and mass spectrometry. NIF specificity was confirmed by dual tissue section staining and 5 recombinant NIF-specific HEK293 cell-based assays (CBAs, for α-internexin, neurofilament light [NfL], neurofilament medium, or neurofilament heavy chain, and peripherin). NIF–immunoglobulin Gs (IgGs) were correlated with neurologic syndromes and cancers.

Results

Among 65 patients, NIF-IgG-positive by IFA and CBAs, 33 were female (51%). Median symptom onset age was 62 years (range 18–88). Patients fell into 2 groups, defined by the presence of NfL-IgG (21 patients, who mostly had ≥4 NIF-IgGs detected) or its absence (44 patients, who mostly had ≤2 NIF-IgGs detected). Among NfL-IgG-positive patients, 19/21 had ≥1 subacute onset CNS disorders: cerebellar ataxia (11), encephalopathy (11), or myelopathy (2). Cancers were detected in 16 of 21 patients (77%): carcinomas of neuroendocrine lineage (10) being most common (small cell [5], Merkel cell [3], other neuroendocrine [2]). Two of 257 controls (0.8%, both with small cell carcinoma) were positive by both IFA and CBA. Five of 7 patients with immunotherapy data improved. By comparison, the 44 NfL-IgG-negative patients had findings of unclear significance: diverse nervous system disorders (p = 0.006), as well as limited (p = 0.003) and more diverse (p < 0.0001) cancer accompaniments.

Conclusions

NIF-IgG detection by IFA, with confirmatory CBA testing that yields a profile including NfL-IgG, defines a paraneoplastic CNS disorder (usually ataxia or encephalopathy) accompanying neuroendocrine lineage neoplasia.

Subacute Cerebellar Degeneration due to a Paraneoplastic Phenomenon Associated with Metastatic Merkel Cell Carcinoma: A Case Report

Purpose

The aim of this article is to illustrate the diagnostic challenges and management of paraneoplastic neurological syndromes in Merkel cell carcinoma.

Materials and Methods

We describe a previously functionally independent 85-year-old woman who presented with subacute onset of dizziness and gait ataxia in the setting of metastatic Merkel cell carcinoma.

Results

Diagnosis was made on biopsy after positron emission tomography imaging revealed increased metabolic activity in 2 left inguinofemoral lymph nodes. Cerebrospinal fluid analysis was positive for anti-Hu on subsequent admission. Her functional status improved with methylprednisolone treatment and radiotherapy.

Conclusion

The case highlights the challenge of the evaluation of patients who present with progressive cerebellar signs and the need to consider a paraneoplastic syndrome, especially in the setting of previous malignancy.