Systematic Review of the Clinical Characteristics and Management of Isaac Syndrome.

OBJECTIVES: Isaac syndrome (IS) is a condition characterized by peripheral nerve hyperexcitability caused by voltage-gated potassium channel (VGKC)-complex antibodies. Muscle twitching, stiffness, hypertrophy, and dysautonomic characteristics, such as hyperhidrosis, are common manifestations. The syndrome can be autoimmune or paraneoplastic, with thymoma being a common cause of paraneoplastic IS. Furthermore, this condition could be handed down from one generation to another. However, there is limited information regarding outcomes, relapses, associated syndromes, associated malignancies (other than thymoma), and treatment options. Despite its rarity, there remains a need for effective management strategies for patients with IS. To address this gap, we conducted a systematic review to summarize the most common and effective treatments of IS in immunomodulatory agents and symptomatic medications, as well as to describe outcomes, relapses, and associated malignancies. Altogether, this review serves to guide clinical practice recommendations for IS and highlight areas for further research. METHODS: We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol to conduct a systematic review of cases reposted through the PubMed and Google Scholar databases. The terms "Isaac Syndrome" and "Acquired Neuromyotonia" were used. The Joanna Briggs Institute's critical appraisal tool was used to evaluate the quality of the included studies. RESULTS: We identified 61 case reports and 4 case series, comprising a total of 70 patients with IS (mean age at onset: 42.5 ± 18 years, and 69% were males). Fourteen cases reported relapses. Thymoma was the most common malignancy associated with IS, followed by lymphoma. Among various serum antibodies, voltage-gated potassium channel-complex antibodies were the most reported antibodies elevated in IS (reported in 38 patients and elevated in 21 patients [55.2%]), followed by acetylcholine ganglionic receptor antibodies, which were reported in 30% of patients (n = 21) and were elevated in 5 cases. The most common electromyography findings were myokymic discharges (n = 22), followed by fasciculations (n = 21) and neuromyotonia (n = 19). For treatment, combining anticonvulsants such as carbamazepine with immunotherapy therapy showed the best results in controlling the symptoms. Among immunotherapy therapies, the combination of plasma exchange plus intravenous high-dose steroids achieved the best results in the acute treatment of IS ([n = 6], with improvement noted in 83.3% [n = 5] of cases). Among the symptomatic treatments with anticonvulsants, carbamazepine was the most efficacious anticonvulsant in treatment of IS, with an average effective dosing of 480 mg/day (carbamazepine was used in 32.3% of acute treatment strategies [n = 23], with improvement noted in 73.9% [n = 17] of cases). CONCLUSIONS: IS a rare neuromuscular syndrome that tends to affect middle-aged men. These patients should be screened for thymoma and other malignancies such as lymphomas. The management of IS symptoms can be challenging, but based on our review, the combination of multiple immunosuppressives such as IV steroids and plasmapheresis with anticonvulsants such as carbamazepine seems to achieve the best results.

Surgical, Radiation, and Systemic Treatments of Patients With Thymic Epithelial Tumors: A Clinical Practice Guideline.

INTRODUCTION: The aim of this guideline was to provide recommendations for the most effective therapy for patients with thymic epithelial tumors, including thymoma, thymic carcinoma, and thymic neuroendocrine tumors (NETs). This guideline is intended to be used by all health care professionals managing patients with thymic epithelial tumors. METHODS: The guideline was developed by Ontario Health (Cancer Care Ontario)'s Program in Evidence-Based Care and by the Lung Cancer Disease Site Group through a systematic review of the evidence, expert consensus, and formal internal and external reviews. RESULTS: Evidence-based recommendations were developed to improve the management of patients with thymic epithelial tumors. The guideline includes recommendations for surgical, radiation, and systemic treatments for patients with thymoma, thymic carcinoma, and thymic NETs separated by stage of disease using the TNM staging system. Recommendations for patients with thymic NETs were endorsed from the 2021 National Comprehensive Cancer Network Neuroendocrine and Adrenal Tumors Guideline. CONCLUSIONS: This guideline reflects the new staging system for patients with thymoma and thymic carcinoma and includes supporting evidence from the best available studies.

Ectopic Cushing's Syndrome due to Thymic Neuroendocrine Tumor Treated with Surgery and Radiotherapy.

The most common cause of ectopic Cushing's syndrome is small cell lung cancer; less common causes include pancreatic and thymic neuroendocrine tumors. A 35-year male was investigated after detecting low potassium in the tests performed for weakness. The patient was admitted for exclusion of Cushing's syndrome because of high cortisol (108 µg/dl) and ACTH (827ng/L) levels. There was no suppression in the high-dose dexamethasone test, and the patient was thought to have ectopic Cushing's syndrome. A mass in the thymus was detected in thorax tomography. Postoperative ACTH and cortisol levels decreased rapidly. Postoperatively, ACTH did not drop to normal, suggesting the possibility of residual tumor. Radiotherapy was given to the patient because the surgical margin was positive in the pathology report. No functional focus was detected in Ga 68 DOTATATE PET CT after radiotherapy. This case is presented because of the rare association of a thymic neuroendocrine tumor with ectopic Cushing's syndrome, which was revealed during the investigation of the etiology of hypokalemia. Key Words: Hypokalemia, Cushing syndrome, Thymic neuroendocrine tumor.

Giant cell myositis associated with metastatic thymoma and granulomatous hypercalcaemia.

Giant cell myositis (GCM) is a rare inflammatory myopathy associated with myasthenia gravis and thymoma. Here, we report on a woman in her late 50s with a history of myasthenia gravis, systemic lupus erythematosus and stage IV thymoma with pleural metastases, who presented with proximal weakness, neuromuscular respiratory failure and hypercalcaemia. She was diagnosed with GCM via muscle biopsy and screened for myocarditis but showed no evidence of myocardial involvement. Her hypercalcaemia was consistent with a granulomatous process, likely driven by her GCM. Her strength gradually improved, and her hypercalcaemia did not recur after treatment with high dose steroids, intravenous immune globulin and plasma exchange. Her course was complicated by several opportunistic infections in the setting of her immunosuppression. Despite the high morbidity associated with GCM, she demonstrated clinical improvement after initiating immunosuppressive therapy and continues to be managed in the outpatient setting.

Isaacs' syndrome as the initial presentation of malignant thymoma and associated with double-positive voltage-gated potassium channel complex antibodies, a case report.

BACKGROUND: Isaacs' syndrome is a peripheral nerve hyperexcitability (PNH) syndrome due to peripheral motor nerve instability. Acquired Isaacs' syndrome is recognized as a paraneoplastic autoimmune disease with possible pathogenic voltage-gated potassium channel (VGKC) complex antibodies. However, the longitudinal correlation between clinical symptoms, VGKC antibodies level, and drug response is still unclear. CASE PRESENTATION: A 45-year-old man had progressive four limbs soreness, muscle twitching, cramps, and pain 4 months before admission. Electromyography (EMG) studies showed myokymic discharges, neuromyotonia, and an incremental response in the high-rate (50 Hz) repetitive nerve stimulation (RNS) test. Isaacs' syndrome was diagnosed based on clinical presentations and EMG reports. Serum studies showed positive VGKC complex antibodies, including leucine-rich glioma-inactivated 1 (LGI1) and contactin-associated protein-like 2 (CASPR2) antibodies. The acetylcholine receptor antibody was negative. Whole-body computed tomography (CT) and positron emission tomography revealed a mediastinal tumor with the great vessels encasement, right pleura, and diaphragm seeding. Biopsy confirmed a World Health Organization type B2 thymoma, with Masaoka stage IVa. His symptoms gradually improved and both LGI1 and CASPR2 antibodies titer became undetectable after concurrent chemoradiotherapy (CCRT) and high dose steroid treatment. However, his Isaacs' syndrome recurred after the steroid was reduced 5 months later. Follow-up chest CT showed probable thymoma progression. LGI1 antibody turned positive again while CASPR2 antibody remained undetectable. CONCLUSIONS: Our patient demonstrates that Isaacs' syndrome could be the initial and only neuromuscular manifestation of malignant thymoma. His Isaacs' syndrome is correlated well with the LGI1 antibody level. With an unresectable thymoma, long-term immunosuppressant therapy may be necessary for the management of Isaacs' syndrome in addition to CCRT for thymoma.

Annona muricata L.-Derived Polysaccharides as a Potential Adjuvant to a Dendritic Cell-Based Vaccine in a Thymoma-Bearing Model.

Dendritic cells (DCs) are powerful antigen-presenting cells that are often used to evaluate adjuvants, particularly for adjuvant selection for various vaccines. Here, polysaccharides (named ALP) isolated from leaves of Annona muricata L., which are used in traditional medicine such as for bacterial infections and inflammatory diseases, were evaluated as an adjuvant candidate that can induce anti-tumor activity. We first confirmed the phenotypic (surface molecules, cytokines, antigen uptake, and antigen-presenting ability) and functional alterations (T cell proliferation/activation) of DCs in vitro. We also confirmed the adjuvant effect by evaluating anti-tumor activity and immunity using an ALP-treated DC-immunized mouse model. ALP functionally induced DC maturation by up-regulating the secretion of Th1-polarizing pro-inflammatory cytokines, the expression of surface molecules, and antigen-presenting ability. ALP triggered DC maturation, which is dependent on the activation of the MAPK and NF-κB signaling pathways. ALP-activated DCs showed an ample capacity to differentiate naive T cells to Th1 and activated CD8+ T cells effectively. The systemic administration of DCs that pulse ALP and ovalbumin peptides strongly increased cytotoxic T lymphocyte (CTL) activity (by 9.5% compared to that in the control vaccine groups), the generation of CD107a-producing multifunctional T cells, and Th1-mediated humoral immunity, and caused a significant reduction (increased protection by 29% over that in control vaccine groups) in tumor growth. ALP, which triggers the Th1 and CTL response, provides a basis for a new adjuvant for various vaccines.

Surgical treatment of pleural recurrence of thymoma: is hyperthermic intrathoracic chemotherapy worthwhile?

OBJECTIVES: Recurrence of thymoma is described in 10-30% of cases after surgical resection. Iterative surgery for thymoma pleural relapses (TPRs) is often part of a multimodal treatment. Hyperthermic intrathoracic chemotherapy (HITHOC) following macroscopic radical surgery is an option that combines the effects of mild hyperthermia with those of chemotherapeutic agents. We evaluated the effectiveness of surgery + HITHOC, compared with surgery alone, in the treatment of TPR. METHODS: We retrospectively collected data of all patients who underwent surgery for TPR in our centre from 2005 to 2017. Relapses were treated by partial pleurectomy with radical intent, followed by HITHOC when not contraindicated. Patients were divided into 2 groups: surgery + HITHOC and surgery alone. We collected demographic and clinical data and analysed postoperative results together with oncological outcomes. RESULTS: Forty patients (27: surgery + HITHOC, 13: surgery alone), mean age 49.8 (±13.7) years, were included in this study. There were no perioperative deaths. We experienced 33.3% perioperative morbidity in the surgery + HITHOC group compared with 23.1% in the surgery alone group (P = 0.71). The overall survival rate was comparable between the 2 groups (P = 0.139), whereas the local disease-free interval was 88.0 ± 15 months in the surgery + HITHOC group and 57 ± 19.5 months in the surgery alone group (P = 0.046). The analysis of factors affecting the outcomes revealed that radical surgery is related with a better survival rate whereas the local disease-free interval was significantly influenced by HITHOC. CONCLUSIONS: The safety and feasibility of HITHOC in the treatment of TPR are already known, even if it should be reserved for selected patients. Surgery + HITHOC seems to be associated with a longer local disease-free time compared to surgery alone.

A "coughed up" tissue diagnosed as type A thymoma in an 80-year-old man: A case report.

RATIONALE: Thymoma is the most common primary tumor in the anterior mediastinum. All major subtypes of thymoma can be clinically aggressive. However, type A thymoma is usually benign and rarely invasive, let alone invasive to the trachea. There are no published reports of thymoma diagnosed in a "coughed up' tissue". Here, we report an 80-year-old man who coughed up a piece of tissue which was histopathologically diagnosed as type A thymoma. PATIENT CONCERNS: An 80-year-old man who had a history of thymoma for 8 years was admitted in our hospital with his severe cough and dyspnea and his "coughed up" something. He felt much better after coughing up the piece of tissue. He saved the tissue and sent it to the pathology department. DIAGNOSES: The clinical diagnosis was lung cancer. But the final pathological diagnosis was type A thymoma. INTERVENTIONS: The patient refused to get chemotherapy, or surgery, and only would like to get the traditional Chinese medicine. OUTCOMES: The patient is stable for 19 months after he coughed up some of the tumor tissue. LESSONS: The type A thymoma could be slowly aggressive. If left untreated, it would also invade into the trachea. When treat a patient with history of even a benign tumor, we should always bear the rare possibility in mind to avoid misdiagnosis. For an elderly patient, a "wait and see" policy may be acceptable.

The role of targeted therapy in thymic carcinoma.

Thymic carcinoma is a rare entity and can be distinguished from benign thymomas by their aggressive nature and poor prognosis. The National Comprehensive Cancer Network guidelines recommend resection followed by adjuvant platinum-based chemotherapy for resectable tumors. However, the outcomes for metastatic or relapsed thymic carcinomas are poor with no regimen showing a consistent benefit. Moreover, the relative rarity of these tumors makes clinical trials difficult. Molecular analysis of thymomas shows a high incidence of genetic mutations and targeted therapy holds promise. We will briefly outline and review the current role of targeted therapy in thymic cancer.

Cytoreductive Pleurectomy and Intrathoracic Chemohyperthermia for Pleural Relapse of Thymomas.

Several surgical procedures, from debulking to extrapleural pneumonectomy, may be applied for stage IVa Masaoka thymomas, but their efficiency is still controversial. Case studies have favored R0 resection as the cornerstone of multimodal therapy for locoregional metastatic extension. This report describes a standardized procedure combining a cytoreductive surgical procedure and intrathoracic chemohyperthermia on a 46-year-old patient presenting with B2 thymoma and synchronous unilateral pleural metastasis.

Is thymomectomy equivalent to complete thymectomy in non-myasthenic patients with early-stage thymoma?

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed is whether thymomectomy can be equivalent to thymectomy for non-myasthenic early-stage thymoma in terms of recurrence and survival. Ten papers were chosen to answer the question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers were tabulated. All studies included in this analysis are retrospective; most of them are small and from single-institution experiences, and only 3 used propensity-matched analysis to minimize the patients' selection bias. The choice of performing thymectomy or thymomectomy was based on surgeons' preference rather than on a standardized surgical approach. Most papers found that thymectomy was equivalent to thymomectomy in terms of outcomes, but these results could be affected by the intergroup differences in terms of follow-up length, administration of induction or adjuvant therapy, histological subtypes distribution and tumour size. Conversely, the studies of the Japanese Association for Research on the Thymus and the Chinese Alliance for Research in Thymoma found a higher rate of local recurrence in the thymomectomy group than in the thymectomy group. The National Comprehensive Cancer Network, National Cancer Institute and International Thymic Malignancy Interest Group recommend complete thymectomy in non-myasthenic patients with early thymoma; therefore, the identified studies in this review are not strong enough to change this recommendation.

Pembrolizumab in patients with thymic carcinoma: a single-arm, single-centre, phase 2 study.

BACKGROUND: Treatment options are limited for patients with thymic carcinoma. These aggressive tumours are not typically associated with paraneoplastic autoimmune disorders, and strong PD-L1 expression has been reported in thymic epithelial tumours. We aimed to assess the activity of pembrolizumab, a monoclonal antibody that targets PD-1, in patients with advanced thymic carcinoma. METHODS: We completed a single-arm phase 2 study of pembrolizumab in patients with recurrent thymic carcinoma who had progressed after at least one line of chemotherapy. This was a single-centre study performed at Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA. Key inclusion criteria were an Eastern Cooperative Oncology Group performance status of 0-2, no history of autoimmune disease or other malignancy requiring treatment or laboratory abnormality, and adequate organ function. Patients received 200 mg of pembrolizumab every 3 weeks for up to 2 years. The primary objective of the study was the proportion of patients who had achieved a response assessed with Response Evaluation Criteria in Solid Tumors version 1.1. Analysis was per protocol, in all eligible patients. The study is registered with ClinicalTrials.gov, number NCT02364076, and is closed to accrual; we report the final analysis. FINDINGS: 41 patients were enrolled from March 12, 2015, to Dec 16, 2016, of whom 40 were eligible and evaluable and one was excluded because of elevated liver enzymes at screening. The median follow-up was 20 months (IQR 14-26). The proportion of patients who achieved a response was 22·5% (95% CI 10·8-38·5); one (3%) patient achieved a complete response, eight (20%) patients achieved partial responses, and 21 (53%) patients achieved stable disease. The most common grade 3 or 4 adverse events were increased aspartate aminotransferase and alanine aminotransferase (five [13%] patients each). Six (15%) patients developed severe autoimmune toxicity, including two (5%) patients with myocarditis. There were 17 deaths at the time of analysis, but no deaths due to toxicity. INTERPRETATION: Pembrolizumab is a promising treatment option in patients with thymic carcinoma. Because severe autoimmune disorders are more frequent in thymic carcinoma than in other tumour types, careful monitoring is essential. FUNDING: Merck & Co.

Case of thymoma-associated cutaneous graft-versus-host disease-like disease successfully improved by narrowband ultraviolet B phototherapy.

Thymoma-associated graft-versus-host disease (GVHD)-like disease is a rare paraneoplastic disease seen in patients with thymoma. Here, we describe the first case of thymoma-associated GVHD-like disease localized to the skin that was successfully improved by a combination of systemic corticosteroids and whole-body narrowband ultraviolet (UV)-B phototherapy. The patient had developed toxic epidermal necrolysis-like erosive skin lesions over the whole body. Although systemic corticosteroids were effective up to a point, we were unable to begin the steroid taper. The addition of systemic narrowband UV-B phototherapy improved the skin manifestation of this disease, allowing corticosteroids to be reduced to a third of the original dose. Histopathologically, it was confirmed that the proportion of Foxp3-positive lymphocytes in the skin increased after narrowband UV-B irradiation. We propose that whole-body narrowband UV-B phototherapy is a good therapeutic option for the skin manifestation of thymoma-associated GVHD-like disease.

Peritoneal recurrence of thymoma treated by surgery and hyperthermic intraperitoneal chemotherapy.

Thymomas are rare (1,5 cases/million) and typically occur in adults with a median age of 50 years old. Thymomas are indolent with a 10-year overall survival for resected stage II thymomas of 70%. Late relapses occur in 20% of the cases, and distant metastasis from thymoma is rare. Peritoneal recurrence of thymoma treated with surgery associated with hyperthermic intraperitoneal chemotherapy (HIPEC) has not been described in the literature. This report manages peritoneal recurrence of thymoma with HIPEC, suggesting that aggressive therapies may decrease the risk of recurrence.

Intra-Thoracic Chemo-Hyperthermia for pleural recurrence of thymoma.

BACKGROUND: Pleural recurrences are a hallmark of thymomas, and represent a challenge for multidisciplinary management. The purpose of this study was to assess the feasibility and the results in terms of morbidity, mortality and survival rates, of Intra-Thoracic Chemo-Hyperthermia (ITCH) for the treatment of pleural recurrences of thymomas. METHODS: Retrospective analysis of 19 consecutives patients between 1997 and 2015 treated by surgical cytoreduction (pleurectomy) followed by ITCH with 25mg/m2 of mitomycin, and 50mg/m2 of Cisplatin. RESULTS: There were 8 men and 11 women with a median age of 44 years. ITCH was combined with pleurectomy alone in 4 (22%) patients, pleurectomy and wedge resections in 14 (74%) patients; 1 (5%) patient had a pleuropneumonectomy. There were no perioperative deaths, and 5 patients (26%) presented with postoperative complication, including 3 (16%) cases related to chemotherapy (one case of reversible grade 2 bone marrow aplasia, and 2 cases of reversible, acute kidney failure). The median length of stay in intensive care unit and hospital were 1day and 10days, respectively. After a median follow-up period of 39 months (range 10-127 months), median disease-free survival was 42 months. Five patients (26%) died during follow-up. CONCLUSIONS: Our data indicate that ITCH is a feasible option for selected patients with pleural recurrence of thymomas. ITCH clearly provides long local control, without major safety issues, and prolonged survival may be achieved in selected patients. This therapeutic option should be discussed at a multidisciplinary tumor board.

The Effect of Immunonutrition on the Postoperative Complications in Thymoma with Myasthenia Gravis.

Object. To test whether preoperative immunonutrition is efficacious in reducing postoperative complications in patients of thymoma with myasthenia gravis (MG). Material and Methods. A total of 244 patients operated on for thymoma with myasthenia gravis were prospectively assigned to two groups, each receiving seven-day preoperative and seven-day postoperative nutrition. The patients in immunonutrition group were given oral immunonutrition (IN). The patients in control group received oral standard nutrition. Immunonutritional and inflammatory biomarkers (IgA, IgG, IgM, CD3t, CD4t, CD8t, CD4t/CD8t ratio, NK-cell, prealbumin, albumin, white blood cells counts, and C-reactive protein) and clinical variables (age, gender, BMI, performance status, type of thymoma, type of MG, operative time, pathology, operative approach, postoperative complications, quantity of drainage, hospital stays) were examined. Results. A significant reduction in the length of hospital stay, quantity of drainage, and postoperative complications was observed in the IN group (p < 0.05). An increase in the level of IgA, IgG, IgM, CD3+T, CD4+T, CD4+T/CD8+T, WBC, CRP, and NK-cell in the IN group was observed after thymectomy, while a decrease was seen with regard to prealbumin and albumin (p < 0.05). Conclusion. Preoperative immunonutrition support is effective in reducing postoperative complications in patients of thymoma with MG. It helps to lower the risk of postoperative infectious complications and hospital stays.

Sorafenib efficacy in thymic carcinomas seems not to require c-KIT or PDGFR-alpha mutations.

PURPOSE: To retrospectively evaluate sorafenib activity and safety in patients with metastatic thymic carcinoma (TC) and to correlate outcome with c-KIT and PDGFR-alpha mutational status. PATIENTS AND METHODS: Patients with metastatic thymic carcinoma treated with sorafenib after at least one prior line of chemotherapy were included. Objective response rate (ORR) and toxicity were evaluated. Analysis of c-KIT and PDGFR-alpha mutational status was performed retrospectively. RESULTS: From October 2007 to August 2011, 5 patients with metastatic thymic carcinoma were evaluated. A median of 8 cycles of sorafenib (range=3-29) were administered. Two patients (40%) displayed a partial response (PR), two patients presented stable disease (SD), while one patient had progression. The median progression-free (PFS) and overall survival were 28 weeks and 92 weeks, respectively. At mutational analysis, only one patient with PR had c-KIT mutation in exon 17 and was successfully treated with sunitinib for 12 months after progression to sorafenib. No PDGFR-alpha mutations were found. CONCLUSION: Sorafenib activity seems independent from the c-KIT and PDGFR-alpha mutational status. After progression, sequence treatment with a different tyrosine kinase inhibitor can be considered. These results are promising and need further confirmation on larger, possibly prospective, series of patients.