Ectopic Cervical Thymoma in a Patient Diagnosed With Graves Disease: A Systematic Literature Review

Thymomas are benign thymic epithelial neoplasms, rarely found outside the anterior mediastinum. Although hyperthyroid states have been associated with thymic hyperplasia, only 3 thymoma cases have been previously reported in patients with Graves disease (GD), all within the anterior mediastinum. Here, we report a case of ectopic cervical thymoma in a 22-year-old female patient previously treated for GD. The patient underwent ultrasonography, computed tomography, inconclusive fine-needle aspiration, and ultimately gross dissection for diagnostic workup and definitive treatment of an anterior neck mass, producing a 2.5 × 2.3 × 1.5-cm entity consistent with Masaoka stage I and type B2 thymoma per World Health Organization classification. The patient underwent an uncomplicated subsequent clinical course, with no adjuvant radiotherapy administered. After conducting a systematic literature review, we conclude that of the 109 cases of ectopic cervical thymoma reported, this is the first to describe a case of ectopic cervical thymoma in a patient with a past medical history of GD. For GD patients in stable euthyroid remission with the persistent or recurrent presence of an anterior neck mass, the extrathyroidal origin of the mass should always be considered, including the exceptional presence of a cervical ectopic thymoma.

A basaloid carcinoma with multilocular thymic cyst mimicking a mediastinal teratoma

This case report details a rare thymic basaloid carcinoma initially misinterpreted as a mediastinal teratoma, underscoring the diagnostic challenges posed by such tumors. A 71-year-old female presented with an asymptomatic anterior mediastinal tumor discovered incidentally during a routine health examination. Surgical intervention, followed by pathological and immunohistochemical analysis including CK-pan, p63, p40, and CD117 molecules, led to a definitive diagnosis of basaloid carcinoma of the thymus. This case highlights the critical importance of differential diagnosis in mediastinal lesions, especially those presenting with multilocular thymic cysts on chest CT. The subxiphoid video-assisted thoracoscopic surgery enabled complete tumor resection with minimal trauma and favorable postoperative outcomes. The patient opted against further radiotherapy or chemotherapy and she has survived for over eight months without recurrence. This case report contributes to the growing understanding of thymic basaloid carcinoma, a rare and potentially aggressive thymic carcinoma subtype. It emphasizes the necessity for precise surgical techniques and enhanced diagnostic acumen among cardiothoracic surgeons and oncologists.

International reproducibility study of thymic epithelial tumors staging: pT stage is an issue. proposals for improvement. A RYTHMIC/ITMIG study

INTRODUCTION

Pathologists are staging thymic epithelial tumors (TET) according to the 8th UICC/AJCC TNM system. Within the French RYTHMIC network, dedicated to TET, agreement on pathologic tumor stage (pT) among the pathology panelists was difficult. The aim of our study was to determine the interobserver reproducibility of pT at an international level, to explore the source of discrepancies and potential interventions to address these.

METHODS

An international panel of pathologists was recruited through the International Thymic Malignancy Interest Group (ITMIG). The study focused on invasion of mediastinal pleura, pericardium, and lung. From a cohort of cases identified as challenging within the RYTHMIC network, we chose a series of test and validation cases (n = 5 and 10, respectively).

RESULTS

Reproducibility of the pT stage was also challenging at an international level as none of the 15 cases was classified as the same pT stage by all ITMIG pathologists. The agreement rose from slight (κ = 0.13) to moderate (κ = 0.48) between test and validation series. Discussion among the expert pathologists pinpointed two major reasons underlying discrepancies: 1) Thymomas growing with their "capsule" and adhering to the pleurae, pericardium, or lung were often misinterpreted as invading these structures. 2) Recognition of the mediastinal pleura was identified as challenging.

CONCLUSION

Our study underlines that the evaluation of the pT stage of TET is problematic and needs to be addressed in more detail in an upcoming TNM classification. The publication of histopathologic images of landmarks, including ancillary tests could improve reproducibility for future TNM classifications.

Unraveling the Natural History of Good's Syndrome: A Progressive Adult Combined Immunodeficiency

BACKGROUND

Good's syndrome (GS) is a rare immune deficiency described almost 6 decades ago. Despite numerous published individual case reports and data collected in cross-sectional studies of small cohorts, the natural history and long-term outcomes of this disease remain unknown.

OBJECTIVE

We aimed to determine the clinical and laboratory evolution of 8 adults diagnosed with GS and consecutively evaluated between 1983 and 2023.

METHODS

In this prospective, longitudinal cohort study, newly diagnosed patients with GS were followed through repeated measures of clinical, immune, and hematologic changes, as well as targeted genetic screening.

RESULTS

All patients reported a healthy childhood and adolescence with symptom onset during the third or fourth decade of life. All presented to our center with recurrent bacterial sinopulmonary infections, thymoma, hypogammaglobulinemia, and absence of B cells. The median age of GS diagnosis was 57 years. During follow-up, immunoglobin replacement therapy effectively minimized sinopulmonary infections. However, the majority experienced severe and systemic viral or fungal infections, 3 developed basal cell carcinomas, and 5 had progressive bronchiectasis and persistent splenomegaly. The most notable clinical feature was opportunistic infections and in vitro evidence of cellular immune deficiency, which resulted in the death of 2 individuals. We also report a statistically significant, multidecade progressive decline in lymphocytes, platelets, hemoglobin, and red blood cells in our cohort, suggesting gradual bone marrow failure.

CONCLUSIONS

Knowledge of the unique phenotype and temporal evolution of GS has allowed us to develop a more comprehensive diagnostic framework. It can be investigated as part of broader research into disease pathophysiology.

[Clinical diagnosis and treatment analysis of 21 cases of intrathyroid thymic carcinoma]

Objective: To analyze the clinical efficacy of intrathyroid thymic carcinoma (ITTC). Methods: This study retrospectively analyzed the clinical data of 21 patients with ITTC diagnosed and treated at the First Affiliated Hospital of Zhengzhou University from January 2018 to July 2023, including 9 males and 12 females, with a median age of 52 years (40-60 years old). Results: There is a correlation between the maximum diameter of the tumor (≥40 mm) and lymph node metastasis (P=0.044). Seventeen patients received surgical treatment, and 4 patients only received chemotherapy. During the follow-up period, a total of 4 patients experienced death or progression, with a 2-year mortality or progression free survival rate of 74.8%. Conclusions: The prognosis of ITTC is good, and surgical treatment is the preferred treatment option, lymph node metastasis is significantly correlated with prognosis. The radiotherapy and chemotherapy of ITTC need to be determined based on the patient's condition.

Metabolic signatures of thymomas: potential biomarkers and treatment targets

OBJECTIVES

A study of tumour metabolic reprogramming has revealed disease biomarkers and avenues for therapeutic intervention. Metabolic reprogramming in thymoma is currently understudied and largely unknown. This study utilized metabolomics and isotope tracing with 13C-glucose to metabolically investigate thymomas, adjacent thymic tissue and benign thymic lesions.

METHODS

From 2017 to 2021, 20 patients with a suspected thymoma were recruited to this prospective Institutional Review Board approved clinical trial. At the time of surgery, 11 patients were infused with 13C-glucose, a stable, non-radioactive tracer which reports the flow of carbon through metabolic pathways. Samples were analysed by mass spectrometry to measure the abundance of >200 metabolites.13C enrichment was measured in patients who received 13C-glucose infusions.

RESULTS

Histological analysis showed that 9 patients had thymomas of diverse subtypes and 11 patients had benign cysts. In our metabolomic analysis, thymomas could be distinguished from both adjacent thymus tissue and benign lesions by metabolite abundances. Metabolites in pyrimidine biosynthesis and glycerophospholipid metabolism were differentially expressed across these tissues.13C-glucose infusions revealed differential labelling patterns in thymoma compared to benign cysts and normal thymus tissue. The lactate/3PG labelling ratio, a metabolic marker in aggressive lung tumours correlated with lactate uptake, was increased in thymomas (1.579) compared to normal thymus (0.945) and benign masses (0.807) (thymic tissue versus tumour P = 0.021, tumour versus benign P = 0.013).

CONCLUSIONS

We report metabolic biomarkers, including differential 13C labelling of metabolites from central metabolism, that distinguish thymomas from benign tissues. Altered glucose and lactate metabolism warrant further investigation and may provide novel therapeutic targets for thymoma.

Erythroderma in a Patient With Thymoma-Associated Myasthenia Gravis

A woman in her 30s with myasthenia gravis diagnosed at age 27 years presented to the emergency department with severe erythroderma over the past 2 months. What is your diagnosis?

Thymoma-associated autoimmune encephalitis with myasthenia gravis: Case series and literature review

OBJECTIVES

This comprehensive review aimed to compile cases of patients with thymoma diagnosed with both autoimmune encephalitis (AE) and myasthenia gravis (MG), and describe their clinical characteristics.

METHODS

Clinical records of 3 AE patients in the first affiliated hospital of Sun Yat-sen University were reviewed. All of them were diagnosed with AE between 1 November 2021 and 1 March 2022, and clinical evidence about thymoma and MG was found. All published case reports were searched for comprehensive literature from January 1990 to June 2022.

RESULTS

A total of 18 cases diagnosed with thymoma-associated autoimmune encephalitis (TAAE) and thymoma-associated myasthenia gravis (TAMG) were included in this complication, wherein 3 cases were in the first affiliated hospital of Sun Yat-sen University and the other 15 were published case reports. 5/18 patients had alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor antibody (AMPAR-Ab) in their serum and cerebrospinal fluid (CSF). All of them had positive anti-acetylcholine receptor antibody (AChR-Ab). And 12/18 patients showed a positive response to thymectomy and immunotherapy. Besides, thymoma recurrences were detected because of AE onset. And the shortest interval between operation and AE onset was 2 years in patients with thymoma recurrence.

CONCLUSIONS

There was no significant difference in the clinical manifestations between these patients and others with only TAMG or TAAE. TAAE was commonly associated with AMPAR2-Ab. Significantly, AE more commonly heralded thymoma recurrences than MG onset. And the intervals of thymectomy and MG or AE onset had different meanings for thymoma recurrence and prognoses of patients.

A Rare Case of Metaplastic Thymoma Presenting With Myasthenia Gravis

Thymomas are tumors of the mediastinum often associated with autoimmune conditions, in particular myasthenia gravis. In contrast, among the fewer than 40 reports of metaplastic thymoma, myasthenia gravis is rarely found. We describe the fourth patient, and first man, with metaplastic thymoma and myasthenia gravis. A 34-year-old had acute onset of double vision with associated dysphagia and was found to have an elevation of serum acetylcholine receptor antibodies. He underwent a transsternal thymectomy. Tissue sections showed a biphasic proliferation of keratin-positive epithelial cells with a complement of spindle cells confirming the diagnosis of metaplastic thymoma. Terminal deoxynucleotidyl transferase (TDT)-positive T lymphocytes were rare and only found in the periphery of the tumor, consistent with thymic remnant. A YAP1::MAML2 gene fusion, with an in-frame fusion between genes YAP1 Exon5 (NM_001130145) and MAML2 Exon2 (NM_032427) was found, supporting further the diagnosis of metaplastic thymoma (Anchored multiplex RNA sequencing [Archer Dx, Boulder, CO] assay). The patient's gender and relatively young age, the presence of an autoimmune condition, and the lack of lymphocytic infiltrate all contribute unusual features to this case and suggest avenues for further exploration.

Disseminated thymoma in pleural fluid: An unusual case

Thymic epithelial tumours show characteristic cytological features on fine-needle aspiration cytology, however the cytological features of thymoma in fluid cytology are not well described. We present the case of a 77 year-old-woman with known pleural dissemination of type B2/B3 thymoma presenting with shortness of breath and orthopnoea due to a pleural effusion. Cytological evaluation of the pleural fluid showed cellular smears composed of numerous small lymphocytes with small numbers of admixed mesothelial cells. There was no epithelial component. On immunohistochemical (IHC) staining the lymphocytes were T cells which were positive for CD3. CD1a and terminal deoxynucleotide transferase (TdT) were also positive, consistent with immature lymphocytes of thymic origin. Despite the lack of an epithelial component, this case was diagnosed as suspicious for recurrent/ metastatic thymoma. This is only the second published case of thymoma identified on pleural fluid cytology, and to our knowledge the first case describing thymoma in pleural fluid with no epithelial component, a potential pitfall with the more common differential diagnosis of a reactive lymphocytic effusion.

Pure white cell aplasia before and after thymectomy in the rare conundrum of thymoma: A case report and review of the literature

RATIONALE

Pure white cell aplasia (PWCA) is a rare paraneoplastic syndrome that occurs in patients with thymomas. Currently, the pathogenesis and treatment of this disease remain in the exploratory stage.

PATIENT CONCERNS

We report a 68-year-old woman with thymoma experienced PWCA involvement as her first presentation. The patient had high fever and agranulocytosis at the onset of the disease. The white blood cell count in the complete blood count was 1.9 × 109/L with a neutrophil of 0.1 × 109/L. The bone marrow aspirates showed decreased granulocyte proliferation. Computed tomography showed a large mass in the anterior mediastinum.

DIAGNOSES

The final diagnosis of our patient was PWCA and thymoma.

INTERVENTIONS

She underwent a thymectomy and cyclosporine A administration during first remission.

OUTCOMES

Long-term remission was achieved following the readministration of cyclosporine A after the disease recurrence.

LESSONS

PWCA or agranulocytosis with thymoma has been confirmed to be an extremely rare disease. Thymomas with PWCA correlate with autoimmunity. From this case study and the literature review, we concluded that the pathogenesis of thymomas in PWCA is mainly related to the activation of autoreactive T cells. Thymectomy and the immunosuppressive drug, cyclosporine A, were chosen for treatment. The patient's granulocyte levels were unable to recover after surgery because of the inability to promptly clear activated T cells. After surgery, cyclosporine A continued to take for a long time. Thymectomy combined with prolonged cyclosporine A administration may be an effective method for treating this rare disease.

Comprehensive study of clinicopathological and immune cell infiltration and lactate dehydrogenase expression in patients with thymic epithelial tumours

BACKGROUND

Lactate dehydrogenase (LDH) has emerged as a promising biomarker for cancer. However, the current understanding of LDH and circulating LDH expression in thymic epithelial tumour (TET) is lacking.

METHODS

A comprehensive literature review and meta-analysis were performed to evaluate the clinical significance of circulating LDH levels in patients with TET. Circulating LDH levels were measured using a laboratory analyser (Cobas8000, Roche, Basel, Switzerland). The maximum standardised uptake value (SUVmax) was determined in patients who underwent whole-body 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). Multiplex immunohistochemistry (IHC) was performed using a commercially available kit (Opal 6-plex Detection Kit, Akoya Biosciences, Marlborough, MA, USA) and slide scanner (Slideview VS200, Olympus, Tokyo, Japan). All statistical analyses were performed using SPSS (IBM Corp., Armonk, NY, USA) and Prism version 9.0 (GraphPad Inc., San Diego, CA, USA). Differences with p < 0.05 were considered to be statistically significant.

RESULTS

Meta-analysis revealed that elevated circulating serum levels of LDH predicted poor prognosis in patients with TET. Circulating levels of LDH were analysed in the serum of 313 patients with TET and 87 with benign mediastinal mass. The mean circulating LDH level in patients with thymic carcinoma (TC) was significantly higher than that in those with thymoma (TM) and the benign group (p < 0.001). Expression levels of circulating LDH were significantly reduced in postoperative samples compared with that in preoperative samples (p < 0.05). Receiver operating characteristic (ROC) curve analysis for diagnosing TC yielded an area under the curve of 0.74, with a sensitivity of 54 % and specificity of 86 %. Furthermore, patients with TC exhibited higher 18F-FDG PET/CT SUVmax values compared to those with TM. Correlation analysis demonstrated a positive association between SUVmax values and circulating LDH levels. In addition, the percentages of LDH-positive cells in TC and type B1 TM tissues were higher than those in other subtypes of TM, and a significant positive correlation between the percentages of LDH-positive and CD20-positive cells was detected in patients with TET (p < 0.05).

CONCLUSION

Circulating serum LDH level may serve as a non-invasive biomarker for the diagnosis and prognosis of TET. The relationship between LDH expression and immune cell infiltration merits further regarding its application in companion diagnosis for immunotherapy.

Thymic epithelial tumours: histopathological classification and differential diagnosis

The epithelial and lymphoid compartments of the thymus can give rise to a wide variety of tumours, including thymomas, thymic carcinomas, lymphoreticular proliferations, germ cell tumours, and sarcomas. While some of these have close similarity to their counterparts in other organs, both in terms of histology and immunohistochemistry, as well as molecular features, others are unique to the thymus. The epithelial tumours, which can develop in the thymus, will be discussed in this review, with a particular emphasis on resolving differential diagnosis by means of morphology, immunohistochemical profiles, and molecular diagnostics.

Exploring Potential Biomarkers of Early Thymoma based on Serum Proteomics

BACKGROUND

Early diagnosis remains difficult because the early symptoms of thymoma are atypical.

OBJECTIVES

This study aimed to analyze the changes of serum proteins in the early stage of thymoma (stage I/II) by proteomics method and to screen and validate candidate biomarkers.

METHODS

Proteins were extracted from 8 sera patients with stage I/II thymoma and 9 healthy controls. The levels of serum proteins were detected by data-independent acquisition (DIA) quantitative proteomics techniques, and the differential proteins were identified. The proteomic results were verified by enzyme-linked immunosorbent assay. Additionally, differentially expressed proteins were analyzed using receiver operating characteristic curves (ROC).

RESULTS

There were 80 differentially expressed proteins between the patients with thymoma and the healthy control group, among which 39 were up-regulated and 41 were down-regulated. Differential protein enrichment is involved in environmental information processing, signaling molecules and interactions, and in the body system and the immune system. The analysis of receptor working characteristic curves showed that the areas under the curve of CORO1A, SAA1 and LTA4H were all larger than 0.8, indicating that these proteins had good diagnostic value.

CONCLUSION

CORO1A, SAA1 and LTA4H may be new biomarkers for early screening of thymoma.

A case of a shrunken multilocular mediastinal cyst that developed into thymic carcinoma with lung metastases 13 years later

Multilocular thymic cysts (MTC) are acquired multilocular cysts caused by inflammation. The rarity of such lesions and a lack of recognition make diagnosis and treatment difficult. Herein, we present our experience with a multilocular mediastinal cyst that resulted in the development of thymic cancer with metastasis over a period of 13 years. Computed tomography findings revealed an anterior mediastinal mass that was suspected to be an MTC in a 49-year-old man. The mass shrank gradually over a period of 7 years; however, growth was observed at 10 years after initial detection. At 13 years after detection, thymic carcinoma with multiple lung metastases was diagnosed. Resection was recommended during the follow-up period, but the patient refused treatment. A multilocular wall and location are factors that indicate MTC. However, even if a definitive diagnosis is not made, resection of multilocular anterior mediastinal cysts should be considered as determining the preoperative diagnosis is difficult. Nevertheless, our case suggests that the coexistence of tumors with cysts is possible, and the potential for malignant tumor development exists.

Diagnostic utility of LMO2 immunohistochemistry in distinguishing T-lymphoblastic leukemia/lymphoma from thymoma

Distinguishing T-lymphoblastic leukemia/lymphoma (T-ALL/T-LBL) from thymomas (especially B1 or B2 type) can be challenging particularly in limited trucut biopsy material where appreciating architecture is difficult or the background epithelial component does not provide tangible evidence for definite diagnosis. As a pathologist, it is important to accurately diagnose these neoplasms because they have entirely distinct management protocols. Recent studies have reported that LIM Domain Only 2 (LMO2) is expressed in neoplastic lymphoblasts of T-ALL/T-LBL and is absent in thymocytes of normal thymuses or thymomas. An observational study was done to test the sensitivity and specificity of LMO2 in differentiating neoplastic lymphoblasts from thymocytes of thymomas/normal thymuses. Our study showed that LMO2 had sensitivity of 70% and specificity of 100% in diagnosing LBL. None of the thymomas (B1 or B2 type) showed expression of LMO2 in the neoplastic cells. LMO2 is a reliable marker of transformed T-cell precursors and should be routinely included in immunohistochemical panel when evaluating thymic/mediastinal neoplasms.

GOOD SYNDROME: CYTOMEGALOVIRUS RETINITIS CASE CHALLENGE

PURPOSE

To describe cytomegalovirus retinitis in a patient with Good syndrome (hypogammaglobulinemia and thymoma), ocular progression despite treatment and fatal outcome.

METHODS

A 71-year-old woman with unilateral panuveitis of unknown cause and a history of thymoma resection was referred to the clinic. Visual acuity was 20/100 in her right eye and light perception in her left eye. In slit-lamp examination, the right eye had inferior, fine, pigmented keratic precipitates, 2+ anterior chamber cells, cataract, and 2+ vitreous cells, with no fundus detail and normal ocular ultrasound results. Left eye presented a white cataract, chronic hypotony, and increased choroidal thickness with calcifications. Laboratory evaluations showed normal or negative results for common causes of infection and inflammation. Prednisolone acetate eye drops were started, with improvement of AC inflammation. Cataract surgery was performed, reaching visual acuity of 20/30. Two years later, visual acuity had decreased and 2+ vitritis and retinitis were found. On clinical suspicion of masquerade syndrome, a vitrectomy biopsy was performed; pathologic assessments reported no data on ocular lymphoma. Leukopenia and lymphopenia were found: immunoglobulin levels, CD4 count, and viral load revealed systemic immunosuppression. The aqueous tap was positive for cytomegalovirus. Oral valganciclovir and intravitreal ganciclovir were initiated.

RESULTS

In a patient with previous resection of thymoma and hypogammaglobulinemia, final diagnosis was Good syndrome, with cytomegalovirus retinitis being secondary to immunosuppression. Despite treatment, cytomegalovirus retinitis progressed and systemic deterioration resulted in mortal outcome.

CONCLUSION

Good syndrome is an extremely rare disease, and association with cytomegalovirus retinitis is uncommon. To the authors' knowledge, only 14 cases exist in the literature.

Paraneoplastic autoimmune neurologic disorders associated with thymoma

Thymoma is often associated with paraneoplastic neurologic diseases. Neural autoantibody testing is an important tool aiding diagnosis of thymoma and its autoimmune neurologic complications. Autoantibodies specific for muscle striational antigens and ion channels of the ligand-gated nicotinic acetylcholine receptor superfamily are the most prevalent biomarkers. The autoimmune neurologic disorders associating most commonly with thymoma are myasthenia gravis (MG), peripheral nerve hyperexcitability (neuromyotonia and Morvan syndrome), dysautonomia, and encephalitis. Patients presenting with these neurologic disorders should be screened for thymoma at diagnosis. Although they can cause profound disability, they usually respond to immunotherapy and treatment of the thymoma. Worsening of the neurologic disorder following surgical removal of a thymoma may herald tumor recurrence. Prompt recognition of paraneoplastic neurologic disorders is critical for patient management. A multidisciplinary approach is required for optimal management of neurologic autoimmunity associated with thymoma.

A case report of dermatomyositis mimicking myasthenia gravis

RATIONALE

Patients who have myasthenia gravis or dermatomyositis show clinical signs of muscular weakening. Ocular muscle involvement is uncommon, and symmetrical proximal limb weakness is the typical presentation of dermatomyositis. However, the earliest and most noticeable sign in those with myasthenia gravis is extraocular muscular paralysis. Dermatomyositis is frequently complicated by malignancy, and the common malignancies associated with dermatomyositis vary by region and ethnicity, while thymoma is relatively rare. About 10% to 15% of people with myasthenia gravis have thymoma, which is involved in the etiology of the disease.

PATIENT CONCERNS

A 68-year-old female presented with ocular muscle weakness for 10 days that manifested as bilateral blepharoptosis with the phenomenon of "light in the morning and heavy in the evening." Imaging examination showed anterior mediastinal thymic tumor with metastasis.

DIAGNOSES

After a thorough physical examination, we discovered bilateral upper limbs with grade IV muscle strength and the typical rash of dermatomyositis. In combination with elevated serum kinase levels and electromyography suggesting myogenic damage, the patient was finally diagnosed as dermatomyositis with multiple metastases of thymoma.

INTERVENTIONS

The patient received oral hydroxychloroquine sulfate, topical corticosteroids, and tacrolimus ointment, but these did not work very well. Subsequently, the patient underwent surgery combined with radiotherapy for the thymoma.

OUTCOMES

Muscle weakness in the patient improved after effective treatment of tumor, and the rash mostly disappeared.

CONCLUSION

Ocular muscle weakness and thymoma are more common in myasthenia gravis, but we cannot ignore the possibility of dermatomyositis. To further establish the diagnosis, a thorough physical examination and laboratory findings are required. Further tumor screening should be performed for patients with dermatomyositis. Early detection and management of possible tumors are essential to the treatment of dermatomyositis linked to malignancies.

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.

Good's syndrome: brief overview of an enigmatic immune deficiency

Good's syndrome, an infrequent adult-onset immunodeficiency is characterized by the triad of thymoma, hypogammaglobulinemia, and increased susceptibility to recurrent infections. The clinical presentation is highly variable, with a spectrum ranging from recurrent bacterial and opportunistic infections to concomitant autoimmune diseases and, sometimes malignant pathologies. Due to heterogeneous clinical phenotypes and the lack of adequate diagnostic criteria, its recognition is often challenging, even delaying it by years. It is one of the most unusual, less studied form of the immune deficiency syndromes with a still unknown pathophysiology. It was initially considered a thymoma-associated variant of primary antibody deficiencies with a reduced or absent number of mature B cells, but it later emerged that significant defects of T cell-mediated immune functions are the underlying cause of opportunistic infections. On the basis of current evidence, Good's syndrome is evaluated as a distinct acquired form of combined immunodeficiency states and classified as a phenocopy of primary immunodeficiency diseases. Epigenetic and acquired genetic factors can play an ultimate role in its evolution.

Spindle-cell thymoma colliding with a bronchogenic cyst in a Yorkshire terrier

An 8-year-old male Yorkshire terrier was presented to the Tufts Veterinary Hospital for evaluation of increased respiratory effort. A mediastinal mass composed of a spindle-cell thymoma within a bronchogenic cyst was diagnosed with computed tomography thoracic imaging, ultrasound-guided fine-needle aspirate biopsy, and histopathologic evaluation after surgical removal. Histologic evaluation showed a multilocular cyst structure as well as a mass characterized by spindle to polygonal thymic epithelial cells. The cyst was characterized by a lining of ciliated pseudostratified respiratory epithelium. To the authors' knowledge, this is the first report of a spindle-cell thymoma being associated with a mediastinal bronchogenic cyst in a dog.

Primary Thymic Hodgkin Lymphoma Coexisting with Thymoma and Myasthenia Gravis: A Case Report

BACKGROUND Myasthenia gravis is a neuromuscular disorder that is strongly associated with thymoma. Although the presence of myasthenia gravis with other tumors is uncommon, approximately 50% of patients with thymoma have myasthenia gravis. Thymic Hodgkin lymphoma should be considered due to the multiple reported cases of patients with myasthenia gravis and Hodgkin lymphoma. In this report, we present the case of 24-year-old woman with myasthenia gravis who was incidentally found to have coexisting thymoma with thymic Hodgkin lymphoma. CASE REPORT A 24-year-old woman with a known case of vitiligo presented with a 2-year history of diplopia and incidental anterior mediastinal mass. Following investigations, myasthenia gravis was diagnosed and managed by pyridostigmine, prednisolone, and azathioprine. Regarding the anterior mediastinal mass, thymoma was suspected based on the presence of myasthenia gravis and radiological findings. She underwent extended transsternal thymectomy. The final histopathological report of the dissected thymus disclosed Hodgkin lymphoma pathology coexisting with thymoma. After the diagnosis of Hodgkin lymphoma nodular sclerosis type IIA was confirmed, 6 cycles of chemotherapy were administered. Four years of follow-up revealed no evidence of Hodgkin lymphoma. However, her symptoms of myasthenia gravis persisted despite Hodgkin lymphoma remission. CONCLUSIONS There is an unclear association between myasthenia gravies and Hodgkin lymphoma. Prior reports revealed regression of myasthenia gravies following Hodgkin lymphoma management, which suggests that myasthenia could be a complication of Hodgkin lymphoma. However, in our case, myasthenia gravis persisted after Hodgkin lymphoma management; therefore, further studies are needed to explore this association.

[Thymoma-associated generalized myasthenia gravis complicated with anti-VGKC complex antibody-associated limbic encephalitis: a case report]

We present a case of a 54-year-old woman. She was attending our department for thymoma-associated generalized myasthenia gravis. While she was treated with intravenous immunoglobulins for the exacerbation of myasthenic symptoms, she suddenly lost her consciousness for the first time and continued to have mild disorientation along with anterograde and retrograde amnesia afterwards. The symptoms improved after steroid pulse therapy. After searching for autoantibodies, she was diagnosed with anti-VGKC complex antibody-associated limbic encephalitis. As one-third of cases are complicated by thymoma, anti-VGKC complex antibody-positive limbic encephalitis has the aspect of a paraneoplastic neurological syndrome. In this case, masses suspected to be a recurrence of thymoma were found. In cases of thymoma, involvement of anti-VGKC complex antibodies should be considered when central nervous system symptoms appear, and when anti-VGKC complex antibodies are positive, recurrence or exacerbation of thymoma should be considered.

Adenoid cystic carcinoma of the thymus gland

BACKGROUND

Thymic carcinomas are rare and aggressive tumours. They constitute a heterogeneous group of tumours with various histological patterns and subtypes resembling epithelial tumours arising from other organs.

CASE PRESENTATION

We hereby represent a case of primary thymic carcinoma with adenoid cystic carcinoma-like features (TCACC) which is an extremely rare variant of thymic adenocarcinoma. To date and to the best of our knowledge, there are nine reported cases in literature and ours is the tenth. Our case was treated surgically but the implementation of adjuvant chemoradiotherapy has been reported in few of the published cases.

CONCLUSIONS

TCACC constitutes a rare entity of thymic adenocarcinoma with limited available literature. The current data is derived from few case reports and case series. The histological overlap of these tumours and primary ACC of salivary glands poses a diagnostic challenge. Radiological investigations, immunohistochemical phenotyping and genetic analysis are crucial in establishing the diagnosis.

Loss of YAP1 C-terminus expression as an ancillary marker for metaplastic thymoma: a potential pitfall in detecting YAP1::MAML2 gene rearrangement

AIMS

Metaplastic thymoma is a rare thymic tumour characterized by Yes Associated Protein 1 (YAP1) and Mastermind Like Transcriptional Coactivator 2 (MAML2) gene fusions resulting from an intrachromosomal inversion of chromosome 11. Immunohistochemistry with an antibody directed against the C-terminus of YAP1 has shown loss of expression in YAP1-rearranged vascular neoplasms, poromas, and porocarcinomas. This study aimed to validate an anti-YAP1 C-terminal antibody as an ancillary immunohistochemical marker for the diagnosis of metaplastic thymoma.

MATERIALS AND METHODS

Ten metaplastic thymomas were selected for the current study. Fluorescence in situ hybridization (FISH), next-generation sequencing (NGS), and reverse transcription-polymerase chain reaction (RT-PCR) analyses were performed to detect YAP1::MAML2 fusions. We then performed immunohistochemistry to detect YAP1 C-terminus expression in 10 metaplastic thymomas, 50 conventional thymomas (10 each of type A thymoma, type AB thymoma, type B1 thymoma, type B2 thymoma, and type B3 thymoma) and seven thymic carcinomas.

RESULTS

All 10 cases showed narrow split signals with a distance of nearly two signal diameters and sometimes had false-negative results in YAP1 and MAML2 break-apart FISH (BA-FISH). Abnormal colocalized signals of the YAP1::MAML2 fusion were observed in all 10 cases using fusion FISH (F-FISH) assays. Eight of 10 cases with adequate nucleic acids were successfully sequenced and all showed YAP1::MAML2 fusions; in two cases the fusions were detected by both DNA and RNA sequencing and in six cases by RNA sequencing only. YAP1::MAML2 fusion transcripts were identified in four cases by RT-PCR. Metaplastic thymoma showed loss of YAP1 C-terminus expression in all 10 (100%) cases. All other thymic neoplasms showed retained YAP1 C-terminus expression.

CONCLUSION

YAP1 C-terminus immunohistochemistry is a highly sensitive and specific ancillary marker that distinguishes metaplastic thymoma from its mimics. BA-FISH assays could not effectively detect YAP1::MAML2 fusions due to the proximity of the two genes. Loss of YAP1 C-terminus expression is a reliable surrogate for the detection of YAP1::MAML2 fusions in metaplastic thymoma.

Not Always a Thymoma - About a Mediastinal Cavernous Hemangioma

A mediastinal cavernous hemangioma is difficult to distinguish from other types of mediastinal tumours. They are usually asymptomatic and incidentally discovered in an imaging study but can present with compressive symptoms or by infiltration of adjacent structures. A 64-year-old woman with a prior history of triple negative invasive carcinoma of the breast, under surveillance was referred after a Chest CT-scan showed a soft tissue 40x20 mm mediastinal mass, suggestive of a thymoma, and as such no tissue biopsy was obtained. A right-side uniportal VATS was performed, the anterior mediastinum dissected and the mass was exposed, and several anomalous veins were identified. Histopathology showed 36x31x15 mm mass, compatible with a cavernous hemangioma of the anterior mediastinum. This case, whilst not questioning the NCCN statement suggesting not doing a tissue biopsy, points to the fact that rare differential diagnosis, like a Cavernous Hemangioma do exist, and a careful and sound judgement is needed at all times.

Unraveling molecular networks in thymic epithelial tumors: deciphering the unique signatures

Thymic epithelial tumors (TETs) are a rare and diverse group of neoplasms characterized by distinct molecular signatures. This review delves into the complex molecular networks of TETs, highlighting key aspects such as chromosomal abnormalities, molecular subtypes, aberrant gene mutations and expressions, structural gene rearrangements, and epigenetic changes. Additionally, the influence of the dynamic tumor microenvironment on TET behavior and therapeutic responses is examined. A thorough understanding of these facets elucidates TET pathogenesis, offering avenues for enhancing diagnostic accuracy, refining prognostic assessments, and tailoring targeted therapeutic strategies. Our review underscores the importance of deciphering TETs' unique molecular signatures to advance personalized treatment paradigms and improve patient outcomes. We also discuss future research directions and anticipated challenges in this intriguing field.

Proteomic analysis identifies argininosuccinate synthetase 1 and special AT-rich sequence binding protein 1 as reliable markers for the immunohistochemical distinction between WHO types A and B3 thymomas

AIMS

The reliable classification of type A versus type B3 thymomas has prognostic and therapeutic relevance, but can be problematic due to considerably overlapping morphology. No immunohistochemical markers aiding in this distinction have been published so far.

METHODS AND RESULTS

We identified and quantified numerous differentially expressed proteins using an unbiased proteomic screen by mass spectrometry in pooled protein lysates from three type A and three type B3 thymomas. From these, candidates were validated in a larger series of paraffin-embedded type A and B3 thymomas. We identified argininosuccinate synthetase 1 (ASS1) and special AT-rich sequence binding protein 1 (SATB1) as highly discriminatory between 34 type A and 20 type B3 thymomas (94% sensitivity, 98% specificity and 96% accuracy). Although not the focus of this study, the same markers also proved helpful in the diagnosis of type AB (n = 14), B1 (n = 4) and B2 thymomas (n = 10).

CONCLUSIONS

Mutually exclusive epithelial expression of ASS1 in 100% of type B3 thymomas and ectopic nuclear expression of SATB1 in 92% of type A thymomas support the distinction between type A and type B3 thymomas with 94% sensitivity, 98% specificity and 96% accuracy.

Thymic hyperplasia with lymphoepithelial sialadenitis (LESA)-like features: a case report and literature review

BACKGROUND

Thymic hyperplasia with lymphoepithelial sialadenitis-like features (LESA-like TH) is a rare form of thymic hyperplasia, characterized by a prominent expansion of the thymic medulla containing hyperplastic lymphoid follicles with germinal centers, while an almost total absence of thymic cortex. Since the first report in 2012, only a few cases of LESA-like TH have been reported in the literature to date. Due to the rarity of LESA-like TH and the tumor-like morphology, it is easy to be misdiagnosed as other common diseases of the thymus in routine practice, such as thymoma and lymphoma.

CASE PRESENTATION

Herein, we present a case report of a 52-year-old Chinese female patient with LESA-like TH, without any discomforting symptoms. Computer-tomography imaging revealed a cystic solid mass in the anterior mediastinum, with well-defined boundaries and multiple internal septa. Histologically, prominent features were florid lymphoid follicles containing germinal centers, as well as hyperplasia of thymic epithelial cells and proliferation of Hassall bodies. However, the thymic cortex rich in immature T cells was almost completely absent. Furthermore, mature plasma cells, lymphoepithelial lesions, and cholesterol clefts were frequently seen.

CONCLUSION

We made a diagnosis of LESA-like TH and performed a literature review to better understand the clinicopathological features of LESA-like TH and reduce misdiagnosis.

Combined Thymic Epithelial Neoplasms - a Review

Thymic epithelial neoplasms are the most common tumors of thymic origin but are overall rare in the general population. Their morphologic diversity, ranging from low grade to overtly malignant lesions, along with various histologic growth patterns make them a diagnostically challenging group of tumors. Very occasionally, thymomas and thymic carcinomas may develop in combination with other benign or malignant lesions of thymic origin, further complicating the diagnostic process. The focus of this review lies on the spectrum of thymic epithelial tumors that present with other thymic lesions in the same tumor mass, such as multilocular thymic cysts, neuroendocrine neoplasms, lymphomas, and germ cell tumors among others. Awareness of the existence of such unusual tumors may not only aid in their diagnosis but may also have implications for prognostic and therapeutic purposes.

Intrathyroidal Thymic Carcinoma: A Retrospective Case Series Study

OBJECTIVE

Intrathyroidal thymic carcinoma (ITC) is a rare low-grade malignant thyroid tumor. There is neither sufficient understanding of this tumor nor its clinical treatment. This study is to explore the clinicopathological features, treatment, and prognosis of ITC and thereby provide a reference for the diagnosis and treatment of the disease.

METHODS

The clinical, pathological, therapeutic, and prognostic data of 13 patients with ITC were retrospectively analyzed.

RESULTS

The case series comprised 7 males and 6 females, with an average age of 51.9 ± 10.1 years. After surgical resection, all patients received post-operative neck radiotherapy at dosages of 60-66 Gy. Five patients with level VI lymph node metastasis additionally received 6 courses of cisplatin chemotherapy. All patients were followed-up for 21-132 months (median = 66 months), and all of them survived without recurrence or metastasis.

CONCLUSIONS

The diagnosis of ITC depends mainly on pathological and immunohistochemical results, particularly CD5 positive staining. Surgical resection is the preferred primary treatment modality which can be supplemented with radiotherapy and chemotherapy to reduce the risk of recurrence and metastasis.

Relapsing COVID-19 infection as a manifestation of Good syndrome: a case report and literature review

Good syndrome (GS) is a rare acquired immunodeficiency disease characterized by the presence of thymoma with combined B and T cell immunodeficiency in adults. Recurrent bacterial infections, particularly sinopulmonary infections caused by encapsulated bacteria, remain the most common infective presentation of GS; however, relapsing viral infections have also been reported, likely due to impaired T cell-mediated immunity. Relapsing COVID-19 infection, however, has not been previously reported as a manifestation of GS. We present two cases of relapsing COVID-19 infection in patients with GS; in one case, relapsing COVID-19 was the first manifestation of newly diagnosed GS.

Clinical characteristics, prognostic factors, and long-term outcomes associated with epithelial malignancies of the thymus: A 20-year single-institution experience

BACKGROUND

Thymic epithelial tumors are rare and include thymomas and thymic carcinomas. There is scarce literature characterizing prognostic factors and long-term outcomes in these tumors.

AIMS

This review aims to describe disease features of thymomas and thymic carcinomas and to report clinical differences among thymoma histological subtypes.

METHODS AND RESULTS

A retrospective chart review was performed at the University of Florida Shands Hospital, a tertiary care academic medical center in Gainesville, Florida, USA. The review included clinical data of adults with thymic epithelial tumors diagnosed between 2001 and 2021. Significant associations among demographics, histology, stage, and outcomes were investigated. Thymoma subgroup analysis was performed using histological subtype and sex. Forty patients with thymoma and seven patients with thymic carcinoma were included in the final analysis. Among those with thymomas, patients with subtype B1, B2, or B3 tumors were younger, had larger tumors, and presented with higher stage disease when compared to those with subtypes A or AB. Tumor recurrence was most common in subtype B2 and B3 tumors (50.0% and 16.7% vs. 0%; p < .01). However, there was no significant difference in overall survival between histologic subtypes. Compared to females, males with thymomas had superior overall survival (103.0 vs. 62.9 months; p = .021) despite presenting with larger tumors (9.8 vs. 5.8 cm; p = .041). Concomitant myasthenia gravis was associated with increased recurrence but not worsened mortality. Compared to thymomas, patients with thymic carcinoma presented with higher-stage disease and had poorer 5-year survival (50.0% vs. 93.1%; p < .01).

CONCLUSION

This study affirmed pathologic stage and resectability as prognostic factors for thymic epithelial tumors. New findings include inferior overall survival in female patients and higher recurrence rates in those with thymomas and concomitant myasthenia gravis.

[Stiff person syndrome associated with thymoma]

Stiff-person syndrome is a rare neurological condition characterized by muscular rigidity of the trunk and extremities and muscle spasms triggered by sensory or emotional stimuli, which progresses towards prostration. It has a pathophysiogenic mechanism with an immunological basis, in which autoantibodies, such as antiGAD65, play a central role. Likewise, the detection of these antibodies corroborates the diagnosis in a patient with a suggestive clinical picture. Four to 6% of cases have underlying neoplasms. Treatment is based on symptomatic, immunomodulatory, and underlying disease management in paraneoplastic cases. We report a case of classic stiff person syndrome associated with thymoma and review the main characteristics of this entity.

Clinical Reasoning: A 59-Year-Old Man With Thymoma and Constitutional Symptoms, Seizures, and Multifocal CNS Lesions

A 59-year-old man first presented for an episode of left arm numbness. During workup, a thymoma was incidentally discovered and resected. The symptoms in his left arm were attributed to a cardiac pathology. One month later, he began to experience fatigue, weight loss, and anorexia, followed by one generalized tonic-clonic seizure. Workup including toxic and metabolic screening and MRI of the brain were unremarkable. He was started on an antiseizure medication and did well for 2 years, when his symptoms recurred. Repeat MRI of the brain showed multiple cortical T2-weighted fluid-attenuated inversion recovery (T2/FLAIR) hyperintense lesions without enhancement or diffusion restriction. Further workup included spinal MRI, CT of the chest/abdomen/pelvis, CSF studies, and autoimmune/paraneoplastic panels in CSF and serum, all of which were unremarkable. Serum testing was positive for striational antibodies, acetylcholine receptor (AChR)-binding antibodies, and AChR-modulating antibodies. He received high-dose steroids and plasma exchange with resolution of his symptoms and has since been stable on mycophenolate mofetil. This presentation highlights the rare association between thymoma and encephalitis. Prompt identification and treatment is critical. This article discusses the diagnostic approach to this rare presentation including essential features of the clinical presentation, appropriate workup, pertinent differential diagnoses, and key points for the treatment of these patients.

Thymoma with systemic lupus erythematosus and immune-related anemia: A case of thymoma with SLE and IRA

INTRODUCTION

Thymic epithelial tumors (TETs), including thymomas and thymic carcinomas. Thymomas are rare tumors, but are one of the most common mediastinal neoplasms in adults. The pathology of thymoma with Systemic Lupus Erythematosus (SLE) and severe pancytopenia is rarely reported. Thus, the current study demonstrates a case of thymoma with SLE and immune-related anemia with unique clinical manifestation.

PATIENT CONCERNS

A 27-year-old woman suffered from abdominal pain, arthralgia, intermittent high fever for a long time.

DIAGNOSIS

Based on the clinical and histopathological manifestations, diagnosis of thymoma with SLE and immune-related anemia was established.

INTERVENTIONS

Patient was treated with methylprednisolone and a complete thymectomy and thymomectomy, the CAP regimen was given 4 times of adjuvant chemotherapy after the operation.

OUTCOMES

After inter-disciplinary consultation as well as extensive discussion and steroid pulse therapy underwent surgery, the patient's blood count and immune function gradually entry sent back to normal.

CONCLUSION

we present the diagnosis and treatment of a case of thymoma with SLE and immune-related anemia, and provides references for the clinical diagnosis and treatment of thymoma combined with SLE, and attempts to explain that SLE patients with thymoma may contribute to the clinical remission of SLE after thymoma resection. It should arouse the attention of clinicians when diagnosing and treating related diseases.

Continuing challenges of primary neuroendocrine tumours of the thymus: A concisereview

Primary neuroendocrine tumours of the thymus (NETTs) are exceedingly rare tumours, usually presenting around mid-life, which have a propensity towards males and smokers. They are seen more often in those with MEN-1, but multiple different genetic mutations have been found to be involved in the tumorigenesis of NETTs. Histologically, NETTs are classified according to number of mitoses, the presence of necrosis, and the presence or absence of small cell features. NETTs display a wide spectrum of behavior, and they can be incidentally found on chest imaging, on screening in MEN-1, or present with symptoms of local compression. Advanced disease and paraneoplastic syndromes are common. CT-, PET/CT-, MRI-scans, and somatostatin receptor scintigraphy are the imaging modalities of choice both for the initial assessment as well as for monitoring after treatment. For patients with localized disease, complete surgical resection with lymphadenectomy provides the best chance of long-term, disease-free survival, and can be achieved through either an open or thoracoscopic approach. While chemotherapy-regimens based on platinum, taxane, and temozolomide are used most often, the optimum chemotherapy regimen in the adjuvant and palliative settings remains unclear, as does the role of radiotherapy. Ongoing research on the most effective use of somatostatin analogues, peptide receptor radionuclide therapy (PPRT), kinase inhibitors and immunotherapy in patients with other types of advanced neuroendocrine tumours may lead to further treatment options for NETTs in the future.

Clinicopathological features and outcomes of intrathyroidal thymic carcinoma: a single institution study

Intrathyroidal thymic carcinoma (ITTC) is a rare malignancy of the thyroid. It is thought to originate from ectopic thymic tissue or embryonic thymic rest, in, or adjacent to, the thyroid. We analyzed the backgrounds, clinicopathological features, and prognosis of 20 patients with ITTC, treated at our hospital. Thirteen of the 15 patients (86%) who underwent ultrasonography were diagnosed as malignant, based on imaging findings. 16 of the 17 patients (93%) who underwent cytology, were diagnosed or suspected to be malignant. Locally curative surgery (thyroidectomy and lymph node dissection) was performed for 19 patients. Large tumor size (>4 cm) was positively related to pathological node metastasis (p = 0.0389). Fourteen patients, including nine Ex-positive patients, underwent adjuvant external beam radiotherapy (EBRT) of the neck after surgery. Two patients showed recurrence of thyroid bed after and neither of them underwent adjuvant EBRT after surgery. Two patients who underwent EBRT showed recurrences of the lateral nodes (level V and level II), but they were easily dissected by re-operation. Ten- and 20-year local recurrence-free survival rates were 84.9% and 60.6%, respectively. To date, four patients showed distant recurrence, and 10- and 20-year distant recurrence-free survival rates were 75.0% and 75.0%, respectively. Our findings indicate that 1) the prognosis of ITTC is generally favorable, and 2) large tumor size is significantly related to lymph node metastasis. Two patients showing recurrence of the central region did not undergo EBRT; thus, further comparative studies are desirable to elucidate whether EBRT can prevent significant local recurrence.

Thymic lipofibroadenoma of the anterior mediastinum: A rare case report

BACKGROUND

Lipofibroadenoma is an extremely rare thymic tumor, and the anterior mediastinum is the most common site.

CASE SUMMARY

A 21-year-old male was admitted with fever without obvious cause for 2 months. After admission, the patient's highest temperature was 38.3°C, accompanied by diarrhea. Physical examination showed coarse breath sounds in both lungs. Chest enhanced computed tomography (CT) showed a mass of mixed density shadow on the left side of the anterior mediastinum with a size of approximately 9.2 cm × 5 cm × 2.1 cm and a clear boundary mixed with a low fat density shadow. Mediastinal tumors were removed under general anesthesia by video-assisted thoracoscopic surgery. Macroscopically, a clear boundary was shown between the tumor and the remaining thymus. Microscopically, the tumor contained a large amount of mature adipose and fibrous tissue with scattered cord-like epithelial tissue and a small number of lymphocytes scattered in the stroma. The tumor lacked thymic bodies. The neoplastic epithelial cells were oval or polygonal and arranged in fissures, the nuclei were uniform in size and mild in shape, and mitosis was rare. Epithelial cells were positive for AE1/AE3 and CK19, lymphocytes were positive for CD3 and CD20, and fat and fibrous tissue were positive for S-100 and vimentin, respectively. The Ki67 labeling index was less than 5%. Based on histological features and immunophenotype, thymic lipofibroadenoma was diagnosed. The patient was followed up 1 year after the operation, and no recurrence or residual lesions were found on the X-ray re-examination.

CONCLUSION

Lipofibroadenoma is a benign thymic tumor, and thymectomy is regarded as the best treatment. The biological behavior of thymic lipofibroadenoma is good, and the recurrence rate is low.

Early Detection of Relapse by ctDNA Sequencing in a Patient with Metastatic Thymic Tumor and MEN1 Mosaicism

CONTEXT

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disease caused by inactivating mutations in the MEN1 gene. In the literature, few cases of MEN1 have been reported because of mosaic MEN1 mutations.

OBJECTIVE

We performed an extensive molecular characterization in several lesions and blood samples, including plasmatic circulating cell-free DNA (ccfDNA) in an exceptional case of a patient with MEN1 mosaicism causing primary hyperparathyroidism, multiple pancreatic neuroendocrine tumors (NETs), and a metastatic thymic NET.

METHODS

Blood, ccfDNA and multiple tissue analysis were performed by next-generation sequencing.

RESULTS

MEN1 mosaicism was confirmed by multiple tissue analysis. Somatic analysis of the largest pancreatic NET revealed the same MEN1 second-hit mutation as found in the thymic lesion, demonstrating its metastatic origin from the thymic lesion. Moreover, in ccfDNA we found the mosaic MEN1 mutation but also the somatic second-hit mutation found in the thymic primary tumor, revealing the presence of circulating tumor DNA (ctDNA). After surgical removal of the pancreatic metastasis, the mutated fraction of both mutations decreased, before increasing again several weeks before a new clinical relapse, suggesting that thymic ctDNA may be used as an early tumor biomarker.

CONCLUSION

This exceptional MEN1 case highlighted (1) the importance of looking for MEN1 mosaicism, (2) that MEN1 mosaicism can cause very aggressive disease, and (3) the interest in analyzing ccfDNA for confirming MEN1 mosaicism but also as a potential tumor biomarker for NET.