Thymic Imaging Pitfalls and Strategies for Optimized Diagnosis

Thymic imaging is challenging because the imaging appearance of a variety of benign and malignant thymic conditions are similar. CT is the most commonly used modality for mediastinal imaging, while MRI and fluorine 18 fluorodeoxyglucose (FDG) PET/CT are helpful when they are tailored to the correct indication. Each of these imaging modalities has limitations and technical pitfalls that may lead to an incorrect diagnosis and mismanagement. CT may not be sufficient for the characterization of cystic thymic processes and differentiation between thymic hyperplasia and thymic tumors. MRI can be used to overcome these limitations but is subject to other potential pitfalls such as an equivocal decrease in signal intensity at chemical shift imaging, size limitations, unusual signal intensity for cysts, subtraction artifacts, pseudonodularity on T2-weighted MR images, early imaging misinterpretation, flow and spatial resolution issues hampering assessment of local invasion, and the overlap of apparent diffusion coefficients between malignant and benign thymic entities. FDG PET/CT is not routinely indicated due to some overlap in FDG uptake between thymomas and benign thymic processes. However, it is useful for staging and follow-up of aggressive tumors (eg, thymic carcinoma), particularly for detection of occult metastatic disease. Pitfalls in imaging after treatment of thymic malignancies relate to technical challenges such as postthymectomy sternotomy streak metal artifacts, differentiation of postsurgical thymic bed changes from tumor recurrence, or human error with typical "blind spots" for identification of metastatic disease. Understanding these pitfalls enables appropriate selection of imaging modalities, improves diagnostic accuracy, and guides patient treatment. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Good syndrome and cytomegalovirus retinitis: A literature review

Good syndrome (GS) is a rare primary immunodeficiency in adults consisting of hypogammaglobulinemia and thymoma that affects both cellular and humoral immunity. It usually appears in patients between the 4th and 6th decade of life and affects both genders equally. Ophthalmological clinical presentation is highly variable; associations with herpetic keratitis, toxoplasmosis, and cytomegalovirus retinitis (CMVR) have been described. GS associated with CMVR is uncommon. Ophthalmologists may be the first to diagnose systemic disease and change the outcome. Only18 cases of CMVR have been described, most of them unilateral with poor visual outcomes. We discuss the clinical features of CMVR in patients with reported GS, pathogenesis, and outline a work-up for diagnosis. CMVR in an apparently healthy patient should encourage the clinician to search for human immunodeficiency virus (HIV) and non-HIV-associated immunosuppression.

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.

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.

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.

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.

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.

Multiparametric Evaluation of Radiomics Features and Dual-Energy CT Iodine Maps for Discrimination and Outcome Prediction of Thymic Masses

RATIONALE AND OBJECTIVES

To investigate the diagnostic value of radiomics features and dual-source dual-energy CT (DECT) based material decomposition in differentiating low-risk thymomas, high-risk thymomas, and thymic carcinomas.

MATERIALS AND METHODS

This retrospective study included 32 patients (16 males, mean age 66 ± 14 years) with pathologically confirmed thymic masses who underwent contrast-enhanced DECT between 10/2014 and 01/2023. Two experienced readers evaluated all patients regarding conventional radiomics features, as well as DECT-based features, including attenuation (HU), iodine density (mg/mL), and fat fraction (%). Data comparisons were performed using analysis of variance and chi-square statistic tests. Receiver operating characteristic curve analysis and Cox-regression tests were used to discriminate between low-risk/high-risk thymomas and thymic carcinomas.

RESULTS

Of the 32 thymic tumors, 12 (38%) were low-risk thymomas, 11 (34%) were high-risk thymomas, and 9 (28%) were thymic carcinomas. Values differed significantly between low-risk thymoma, high-risk thymoma, and thymic carcinoma regarding DECT-based features (p ≤ 0.023) and 30 radiomics features (p ≤ 0.037). The area under the curve to differentiate between low-risk/high-risk thymomas and thymic cancer was 0.998 (95% CI, 0.915-1.000; p < 0.001) for the combination of DECT imaging parameters and radiomics features, yielding a sensitivity of 100% and specificity of 96%. During a follow-up of 60 months (IQR, 35-60 months), the multiparametric approach including radiomics features, DECT parameters, and clinical parameters showed an excellent prognostic power to predict all-cause mortality (c-index = 0.978 [95% CI, 0.958-0.998], p = 0.003).

CONCLUSION

A multiparametric approach including conventional radiomics features and DECT-based features facilitates accurate, non-invasive discrimination between low-risk/high-risk thymomas and thymic carcinomas.

Intrathyroid thymic carcinoma: A clinicopathological analysis of 22 cases

OBJECTIVE

Intrathyroid thymic carcinoma (ITTC) is a rare malignancy. The current understanding of ITTC is inadequate, and there is no standard treatment for ITTC. In the present study, we aimed to explore the clinicopathological characteristics of ITTC and identify potential therapeutic targets.

METHODS

The clinicopathological characteristics of 22 ITTC patients at our institution were reviewed. The expression of DNA mismatch repair (MMR) proteins and PD-L1 in ITTC were assessed by immunohistochemistry (IHC).

RESULTS

All patients underwent surgery. There were nine females and 13 males, with a slight male predominance. Their ages ranged from 42 to 79 years (average, 54. 1 years). The diameters of the neck masses ranged from 10 to 100 mm (average, 39 mm). Ipsilateral lymph node (LN) dissection was performed in 18 patients: 12 demonstrated LN metastasis, six showed no LN metastasis, and no lymph nodes were dissected in four. One patient had liver metastasis. CK5/6, P63, CD5, and CD117 were expressed in all cases. All cases were negative for TTF1, PAX8, thyroglobulin, and BRAF V600E. DNA MMR protein expression was retained in all tested tumors, and EBV-encoded small RNA (EBER) in situ hybridization was consistently negative. The Ki67 proliferation index ranged from 10 to 70 %. All patients were followed-up for 14-134 months, four died, six were lost to follow-up, and the remaining patients survived without disease. The PD-L1 combined positive score ranged from 10 to 80 (average: 40).

CONCLUSION

Our results confirm that CD5 and CD117 co-expression support a diagnosis of ITTC. All tumors in this cohort were DNA MMR-proficient and were not associated with Epstein-Barr virus (EBV) infection. A high CPS for PD-L1 suggests that immune checkpoint inhibitor therapy may be worthy of further exploration in patients with ITTC.

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.

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.

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.

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.

[Patient with Good's syndrome and COVID-19. Report of a clinical case]

BACKGROUND

The consequences of SARS-CoV-2 infection in patients with primary (now called "inborn errors of immunity") or secondary immunodeficiencies is still a matter of debate. There are few reports in the literature of patients with Good's syndrome and SARS-CoV-2 infection with variable outcomes.

CLINICAL CASE

A 51-year-old male with diagnosis of Good's syndrome treated with intravenous human immunoglobulin (IVIG) at a replacement dose with application every 21 days and prophylaxis for P. jirovecii with trimethoprim/ sulfamethoxazole due to profound lymphopenia at expense of T CD4+ lymphocytes who presented initially mild disease (RT-PCR+) that progressed to pneumonia with acute respiratory failure and required advanced airway management and admission to the ICU with a fatal outcome due to superinfection after 14 days hospitalized.

CONCLUSION

It has been documented in patients with humoral immunodeficiencies a better prognosis for developing less intense cytokine release syndrome. The alteration in cellular immunity, especially lymphopenia at the expense of CD4+ T lymphocytes, may be associated with a worse prognosis as the response against viruses is compromised as well as high susceptibility to superinfection by opportunistic agents such as P. aeruginosa and Mucor sp. For this reason, we must maintain close surveillance in patients with inborn errors of immunity with cellular defects, as is the case of patients with Good's syndrome who present with COVID-19.

Rippling Muscle Disease with Irregular Toe Jerks and Anti-acetylcholine Receptor Antibodies: Remission after Extended Thymectomy

We herein report a 63-year-old rippling muscle disease (RMD) patient who presented with painless stiffness, muscle hypertrophy and muscle contractions elicited by mechanical stimulation. He also showed irregular toe jerks and a slightly elevated level of anti-acetylcholine receptor antibody (AChR-Ab). Since he had a mediastinal mass mimicking thymoma, which was later revealed to be a bronchial cyst, he underwent extended thymectomy. The irregular toe jerks disappeared within a week after the operation. The other muscle symptoms completely remitted 27 months after the onset. This is the first report of a sporadic case of RMD with irregular toe jerks that resolved after extended thymectomy.

Intrapericardial Thymoma Presented as Pericardial Tamponade with Post-Operative Myasthenia Gravis

Background: Thymoma is an epithelial mass arising from the thymus. Most thymomas are located in the anterior mediastinum. Ectopic intrapericardial thymoma is very unusual; to date, only eight cases of pericardial thymoma have been reported. Among thymoma patients, 20% to 25% are associated with myasthenia gravis. However, postoperative myasthenia gravis occurs in less than 1% of cases. Here, we share a rare case of ectopic intrapericardial thymoma that developed postoperative myasthenia gravis six months after surgery. Case presentation: A 66-year-old woman visited the outpatient department due to productive cough and chest pain. Chest radiography showed increased soft tissue opacity over the mediastinum. A soft tissue mass in the pericardium and a ground glass nodule in right upper lung were noted using chest computed tomography. The diagnosis of thymoma, type B2, pT3N0M0, and stage IIIA and synchronous adenocarcinoma in situ of the right upper lung was confirmed after surgical removal. Six months later, the patient developed postoperative myasthenia gravis. Conclusions: Thymoma is rarely considered a differential diagnosis in pericardial tumors. Surgical removal with adjuvant radiation therapy should be performed considering the malignancy potential of thymomas and cardiac complications. In patients without myasthenia gravis, a small chance of postoperative myasthenia gravis remains. Patients should be carefully monitored for myasthenia gravis after surgery.

Five Times Reactivation of COVID-19 in a Patient with Thymoma

BACKGROUND

The possibility of recurrence in COVID-19 is very rare and hence mostly underdiagnosed. In the face of pandemic, this can lead to circulation of the virus like a hidden iceberg. Better understanding about this topic can improve our knowledge of the COVID-19 pathogenesis and ways to control the transmission.

CASE PRESENTATION

A 41 year old male with no known comorbidities was admitted five times during a period of 7 months each time after being detected RTPCR positive for SARS-CoV-2 and more symptomatic than previously. He had no contact with other COVID-19 patients and was asymptomatic in between admissions. Despite this, he did not develop antibodies against SARSCoV-2. Later on, he was diagnosed with thymoma on biopsy of the anterior mediastinal mass. Patient's condition deteriorated on last hospitalization and he died, despite the treatment. Here we present an interesting report on multiple times recurrent COVID-19 infection, probably a case of reactivation and different plausible explanations on the role of thymoma.;Conclusion: Acknowledging the potential of SARS-CoV-2 to cause recurrence is very important during the pandemic as a part of the long term transmission mitigation. The case report shows that previous infection does not guarantee complete immunity from COVID-19, especially in immuno-compromised patients. Hence, despite the status of prior infection, vulnerable individuals who recovered from COVID-19 should be under surveillance.

An unusual presentation of thymoma: dysgeusia, ulcerative colitis, keratoconjunctivitis sicca, autoimmune retinopathy and myasthenia gravis

A 41-year-old female presented with dysgeusia, dry eyes, nyctalopia with progressive visual field constriction (due to autoimmune retinopathy) and gastrointestinal symptoms (due to ulcerative colitis). She was subsequently admitted to intensive care with a myasthenic crisis, and CT of the thorax demonstrated a thymoma.Following thymectomy and adjuvant radiotherapy, she has remained in complete remission from her ulcerative colitis and myasthenia gravis, her retinopathy has stabilised and there has been no thymoma recurrence over a 10-year postoperative period. There was a brief relapse of her dysgeusia (causing weight loss) and dry eye symptoms 3 years after her surgery, which resolved 8 months later. While the association of thymomas with paraneoplastic syndromes (PNS) is well established, it is unusual to present with multiple PNS, and some of these have only been documented in sparse case reports to date. Thymectomy played a crucial role in improvement and stabilisation of her PNS.

Juan Rosai as master of our comprehensive understanding of thymus and thymoma

In this study, the authors report on the activity of Juan Rosai, one of the pathologists most engaged in the definition of cells, diseases and tumors occurring in the thymus and in the mediastinum during the last 60 years. With his morphological skills and tireless interest in clarification of disease patterns, he contributed extraordinarily to expand our knowledge of the mediastinal diseases and to improve our diagnostic approach. He determined extraordinary advances also in trasmission electron microscopy and in immunohistochemistry as powerful diagnostic tools. Moreover, he proposed and promoted, together with an international panel of Pathologists, the World Health Classification of Thymic tumors as a definite progress in our comprehension and diagnostics of thymic epithelial tumors (TET). Our purpose is to review J. Rosai's achievements in thymic normal structure, in TET and particularly in the entity now definied as "thymoma", in distinction from the thymic carcinoma. To do this, our narrative will also be based on personal memories, longstanding collaborations and/or friendship with J. Rosai.

T-Lymphoblastic Leukemia/Lymphoma and Thymoma: A Case Report and Review of the Literature of a Rare Association

The co-occurrence of thymoma and T-lymphoblastic lymphoma/leukemia is an extremely rare but previously reported association that poses a diagnostic and therapeutic challenge. We describe a 67-year-old patient with long-standing untreated B1 thymoma that presented with constitutional symptoms and a painless soft tissue mass on the right chest wall. Pathological analysis of the biopsy from the mass demonstrated T-lymphoblastic leukemia/lymphoma. The patient went through a complicated course, was refractory to several lines of therapy, and eventually underwent allogeneic hematopoietic stem cell transplantation in complete remission from a matched related donor. The association between thymoma and malignant neoplasms has been described in the literature, most notably with colorectal adenocarcinoma and thyroid cancer. Thymoma-associated leukemia is, however, extremely unusual, with limited reports in the literature. Distinguishing between thymoma and leukemia can be challenging and often requires meticulous diagnostic efforts. For patients with a past history of thymoma, awareness of this particular association should be bared in mind to allow earlier diagnosis and therapy.

Thymoma-Related Paraneoplastic Syndrome Mimicking Reactive Arthritis

Background and Objectives: Thymomas are associated with a high frequency of paraneoplastic manifestations. Paraneoplastic syndrome (PNS) with thymoma presents a challenge to clinicians because of the need to decipher the association between the presenting symptoms and the underlying tumor. The condition most commonly noted in patients with PNS with thymoma is myasthenia gravis. Other common autoimmune diseases that may present as PNS include systemic lupus erythematosus, pure red cell aplasia, and Good syndrome. Seventy-six percent of patients with PNS-associated thymoma experience resolution of PNS after curing thymoma. Materials and Methods: A 37-year-old man with a two-month fever accompanied by polyarthritis accidently found thymoma after contrast computed tomography scans of his chest. He accepted Video assisted thoracoscopic surgery with resection of thymoma. Results: Fever and polyarthritis resolved after operation but recurred in five days due to cytomegalovirus viremia, which might be predisposed by previous antibiotics treatment before the diagnosis of thymoma. Conclusion: Patients with a thymoma also have a high frequency of PNS, and the most frequent condition found in patients with PNS-associated thymoma is myasthenia gravis. Fever with polyarthritis has been rarely reported as a symptom of PNS-associated thymoma. Here we reported an unusual case of PNS mimicking reactive arthritis with thymoma, as diagnosed based on the patient’s clinical progression, imaging examination, and laboratory tests. The patient died of his comorbidities, and his death may have been related to long-term antibiotic use and consequent intestinal dysbiosis. This challenging case may help to inform clinicians of the need for detailed work-up of fever with unknown origin in the presence of chronic polyarthritis to prevent the overdiagnosis of inflammatory arthritis or rheumatic disease and avoid further comorbidities. Detailed work-up should include the patient’s history of infections, inflammation, and malignant or nonmalignant tumors.

Thymoma: Challenges and Pitfalls in Biopsy Interpretation

The interpretation of biopsy specimens in the diagnosis of thymoma is a subject that is generally not addressed in the literature. Even though the diagnosis of thymoma may seem to be an easy step in the assessment of these tumors, in reality, it is the biopsy specimen interpretation that will be use to determine course of action in any particular patient. It may determine whether a patient is a surgical candidate or on the contrary whether a patient may be benefited the most by medical therapy. In addition, there may be conditions in which all that is required is surgical resection without any further treatment, and that the evaluation of those conditions does not necessarily required the careful pathologic staging that thymomas need. In addition, it is important to highlight that in small biopsies, there are limitations not only in terms of the cellularity and other features that may not be present in such biopsy but also the limitation in term of immunohistochemical interpretation. Herein we have attempted to highlight numerous tumoral conditions that are frequently encountered in the daily practice of mediastinal pathology, some of them pose significant problems in separating them from thymomas. Needles to say, the entire spectrum of mediastinal pathology that may at any given time mimic thymoma is well beyond the scope of this review. Furthermore, we also herein emphasize the need for proper clinical and radiologic information and correlation in order to lead to a better interpretation of the biopsy specimen. The emphasis in this review is on thymoma and their possible pitfall and shortcomings while evaluating small biopsy specimens.

Multi-institutional survey of thymic carcinoma patients in Hokushin region

BACKGROUND

Thymic carcinoma is a rare neoplasm, and its prognosis is very poor. The purpose of this study was to validate the clinical and epidemiological factors, diagnosis and initial treatment of thymic carcinoma among all patients diagnosed in the registered hospital group.

METHODS

We surveyed retrospective data from 152,921 cancer patients in 22 principal hospitals.

RESULTS

A total of 88 thymic carcinoma cases were newly diagnosed. These patients were 50 men and 38 women, with a median age of 66 years old. Eight patients were discovered in cancer screening, 9 in a voluntary setting, 14 at health checkups, 25 at follow-up of other diseases, and 32 cases by introduction from another hospital. Only 14 cases had been diagnosed with localized disease, but 5 cases were accompanied by regional lymph node metastasis. Furthermore, 12 cases showed infiltration into adjacent organs, and 24 cases had distant metastasis. Eighty-three cases were diagnosed by a pathological diagnosis. A surgical approach, chemotherapy, and radiotherapy were performed for 29, 35 patients, and 31 patients, respectively, while 17 patients received best supportive care.

CONCLUSION

The diagnosis of thymic carcinoma is still difficult, and this disease has a tragically rapid progression if when discovered during follow-up of other diseases. An innovative modality for the early detection of thymic carcinoma is needed in modern medical society.

Primary thymus tumors: retrospective case analysis at a reference center in Latin America, 2011-2019

BACKGROUND

Thymic tumors are unusual neoplasms, representing 0.2 to 1.5% of tumors in humans, but correspond to 20% of mediastinal tumors and 50% of those that occur in the anterior mediastinum. They tend to appear around the fourth and fifth decades of life without gender predilection. Up to 30% of patients are asymptomatic, therefore many are incidentally diagnosed. Radical thymectomy is the treatment of choice with high survival rates when detected in the early stages.

METHODS

This was a retrospective descriptive study, including 18 adult patients' diagnosis of thymic neoplasm, who were managed with surgical resection from 2011 to 2019. Information about demographics, clinical characteristics, imaging findings, surgical and medical management, plus histological findings was obtained and reported.

RESULTS

18 patients with thymic tumors were included, of which specific histologic studies reveled thymomas, carcinomas, neuroendocrine tumors, thymolipoma and thymic cyst. Mean age was 52.7 years, with a predominance of male population. The main symptom was dyspnea, followed by cough and chest pain. Paraneoplastic syndromes such as myasthenia gravis, aplastic anemia and Cushing syndrome were reported. 89% of cases were treated by radical thymectomy alone, while only 2 cases required chemotherapy and radiotherapy. There were no surgical complications. Mean hospital stay length was 11. 9 days, with only 1 mortality during hospital admission. 5-year survival rate was 81%.

CONCLUSIONS

The treatment of choice is radical thymectomy, which has been shown to positively impact patient mortality. Early detection is key to improve patient outcomes.