Thymic Lesions Research Articles

Characteristics and Treatment Outcomes of Pediatric Langerhans Cell Histiocytosis with Thymic Involvement

To evaluate the characteristics and treatment outcomes of patients with pediatric Langerhans cell histiocytosis (LCH) with thymic involvement. We retrospectively described the clinical, biological, and imaging characteristics of a series of 19 patients with pediatric LCH with thymic involvement in our center between September 2016 and December 2019. We further analyzed the treatment response and outcomes of patients treated with chemotherapy or targeted therapy. Thymic involvement was found in 4.4% of a 433-consecutive pediatric LCH cohort; all LCH-thymic involvement presented with multisystem disease. Patients with thymic involvement were typically younger, harboring more lung and thyroid involvement and less bone involvement than those without thymic involvement. Most patients with thymic involvement had alteration of immunocompetence with decreased numbers of T-lymphocyte subsets and immunoglobulin G levels. Overall, 47.1% of patients demonstrated a response after 6weeks of induction therapy, and 92.3% of the patients who did not respond to the first-line treatment had resolution of thymus after the second-line and/or targeted therapy. The progression/relapse rate showed no difference between patients who shifted to second-line therapy and those to dabrafenib (33.3% vs 25%, P=1.000). The survival for patients with thymic involvement did not differ from those without thymic involvement. More patients treated with second-line chemotherapy had severe adverse events than those given dabrafenib (88.9% vs 0, P<.001). Thymic involvement was observed rarely in LCH and had specific clinical characteristics. Chemotherapy could resolve most thymic lesions, and BRAF inhibitors might provide a promising treatment option with less toxicity for infants with BRAF-V600E mutation. http://www.chictr.org.cn, identifier: ChiCTR2000030457 (BCH-LCH 2014 study); ChiCTR2000032844 (dabrafenib study).

Clinical spectrum of myasthenia gravis: An institute experience over 8 years from North East India.

Myasthenia gravis (MG) is a neuromuscular junction disorder usually associated with a thymic lesion. To study the clinical, serological, and thymic pathology in patient of MG from this corner of the country. A retrospective study involving all myasthenia patients presenting to neurology and cardio-thoracic department from the year 2013 to 2020. The clinical findings, Osserman grade of severity, antibodies profile, computed scanning thorax findings and histopathology of the thymic lesion were noted and collected as data. Thirty patients of MG were included with mean age of onset being 39.10 ± 15.77 years which included 22 females and eight males. Four patients had only ocular findings while 26 patients had generalized myasthenia with three patients of respiratory failure. Ach receptor antibodies were positive in 27 patients and negative in two patients. Anti-MUSK was positive in one out of five patients. Abnormal findings in CT thorax seen in 20 patients which included enlarged thymic gland in 11 patients, thymic hyperplasia in two patients, thymoma in four patients, and anterior mediastinal mass in three patients. Thymectomy was done in eighteen patients with thymoma as the most common histopathological findings seen in eight patients, follicular hyperplasia in five patients; other was thymic hyperplasia, thymic cyst, normal thymus gland, and features of sarcoidosis in one patient. MG is a treatable autoimmune disorder with a variety of clinical, radiological, and histopathological findings.

AB008. Synchronous thymic and breast malignancies: a single institutional experience

: Breast cancer is the most frequent neoplasm in female population. Conversely, thymic epithelial tumors (TETs) are rare diseases, often discovered in late stages. TET patients have a high risk of developing secondary malignancies compared with general population, with an incidence rate from 8 to 31%. We recently observed the synchronous appearance of both these neoplasms in two patients. The first patient, a 60-year-old female, was diagnosed with breast cancer. She underwent quadrantectomy and sentinel axillary lymph node dissection. Pathological diagnosis was invasive breast cancer non special type (NST), G2 pT1 N0, estrogen receptor (ER) 95%, progesterone receptor (PR) 90%, human epidermal growth factor receptor 2 (Her2) negative, Ki67: 30%. Staging work-up (chest X-ray followed by CT scan) discovered a solid mass of 70 mm in the anterior mediastinum, suspect for thymic tumor lesion, that also showed a tracer uptake at FDG scan (SUVmax 10). Patient underwent thymectomy with pathologic diagnosis of thymoma, subtype B2/B3, stage pT1a pN0 (AJCC TNM 8th edition). The second patient, a 62-year-old woman experiencing post-COVID persistent dyspnea, underwent a CT scan and an FDG PET scan. Imaging showed a thoracic lesion suspicious for thymic neoplasm infiltrating the chest wall (tracer uptake SUVmax 6.7) and simultaneously two contrast-enhanced nodules, one in each breast (left breast: 15 mm, SUVmax 2; right breast: 20 mm, SUVmax 2.6). Surgical biopsies were performed in all the 3 lesions. The pathological diagnoses were: (I) non keratinizing squamous cell carcinoma of the thymus; (II) invasive left breast cancer (NST) ER 90 %, PR 30%, Her2 negative, Ki67: 10%; (III) invasive right breast cancer (NST) ER 90%, PR 30%, Her2 positive (3+), Ki67 10%. The presence of synchronous thymic and breast malignancies appears to be very singular and requires personalized treatment strategies. Furthermore, additional studies are needed to understand if TETs and their related immune system dysregulation could increase the risk of secondary tumors, or whether genetic disorders might be responsible for an increased predisposition to develop synchronous malignancies. In both scenarios, future studies should explore the utility of tailoring screening procedures for TET patients.

Differential diagnosis of thymic epithelial neoplasms on computed tomography using the diameter of the thymic vein.

Although differentiating benign and malignant thymic epithelial lesions is important to avoid unnecessary treatment and predict prognosis, it is challenging because of overlaps in the chest computed tomography (CT) findings. In this study, we investigated whether the diameter of the thymic vein and other CT findings could differentiate between benign (thymoma and thymic cysts) and malignant (thymic carcinoma, [TCa]) lesions.We conducted a retrospective study across two tertiary referral hospitals in Japan between November 2009 and June 2018. We included 12 patients with TCa, 34 patients with thymomas, and 17 patients with thymic cysts. We analyzed the receiver operating characteristic (ROC) curve to determine the best cut-off values and performed univariate and multivariate analyses of CT findings to distinguish TCa from other benign lesions. Post-hoc analysis was performed for the maximum short axis of the thymic vein using the Mann–Whitney U test, and the number of the maximum short axis of the thymic vein ≥ the cutoff was determined using the Fisher exact test with a family-wise error-correction using Bonferroni's method.ROC analysis showed that a maximum short axis of the thymic vein ≥2 mm was considerably more frequent in TCa than in the other lesions (P < .001 for both), with 83% sensitivity and 86% specificity. Univariate and multivariate analyses revealed the association with TCa of the number of the maximum short axis of the thymic vein ≥2 mm (P = .005, multivariate generalized linear model analysis), ill-defined margin (P = .001), and mediastinal lymphadenopathy (P < .001). Thymic vein diameter was in descendimg order of TCa > thymoma > thymic cysts with statistically significant differences between the groups (Ps < .05).Thymic vein diameter was significantly longer in TCa than in thymoma and thymic cysts. Measurement of the maximum short axis of the thymic vein could be a powerful diagnostic tool to differentiate TCa from thymoma and thymic cysts.

Longitudinal CT and MRI Characteristics of Unilocular Thymic Cysts.

Background Isoattenuating and hyperattenuating thymic cysts at CT are often misinterpreted as lymphadenopathy or thymic epithelial neoplasms. Purpose To evaluate the longitudinal change in thymic cyst appearance at CT and MRI. Materials and Methods All chest MRI studies showing thymic cysts between July 2008 and December 2019, identified from a retrospective search of a quality assurance database, were included in this study if initial CT depicted a thymic lesion, the patient was referred for follow-up MRI for characterization, and the baseline (ie, index) MRI indicated a cystic lesion. Follow-up CT scans and/or MRI scans were identified through July 2020. Thymic cyst characteristics, such as size, location, and morphologic features, as well as CT and MRI characteristics, were recorded. Change in size, attenuation, and T1-weighted MRI signal was assessed longitudinally. Descriptive statistics of longitudinal change were tabulated. Results A total of 244 chest MRI studies in 140 patients with 142 unique cysts and 392 CT examinations (636 total examinations and 645 thymic cysts-nine examinations with two cysts each) were evaluated. The median follow-up duration was 2.2 years. Thirty-three patients with 34 unique cysts (34 of 142 cysts [24%]) underwent imaging follow-up for more than 5 years. Thymic cysts followed up for more than 5 years were most commonly saccular (189 of 274 cysts [69% axially]) and retrosternal (14 of 34 cysts [41%]). Craniocaudal dimension was larger than transverse and anteroposterior dimensions in 223 of 274 cysts (81%). Mean thymic cyst attenuation was 25 HU (range, 15-100 HU). Five of 31 cysts (16%) exhibited wall calcification. The median cyst wall thickness was 2.0 mm (range, 0.9-3.0 mm). Most thymic cysts changed in volume (31 of 34 cysts [91%]), CT attenuation (15 of 35 cysts [43%]), and T1-weighted MRI signal (12 of 18 cysts [67%]) over time. None developed mural irregularity, nodularity, or septations. Conclusion Unilocular thymic cysts, defined at index MRI, never developed irregular wall thickening, mural nodularity, or septations that would raise concern for malignant transformation. However, these cysts showed mural calcification and change in size, CT attenuation, and MRI signal over more than 5 years of follow-up. © RSNA, 2021 Online supplemental material is available for this article.

Thymolipoma’s association with myasthenia gravis: Report of three cases

Thymolipomas are rare, benign thymic lesions (2%-9% of thymic tumors) and has scarce local and systemic manifestations. Myasthenia gravis (MG)’s association with thymolipomas is uncommon, with just 34 cases reported in the literature until August 2020.

The Rarest of Rare Thymic Lesions: A 10-Year Surgical Pathology Experience.

Simple SummaryThe thymus is the last organ in the human body to have its mechanisms fully understood. Its intrinsic complex morpho-functional structure reflects the complexity and variety of the pathological lesions of the gland. These include some variants of neoplastic and nonneoplastic processes, which are considered the rarest of the rare ones. The aim of this work is to describe the rarest lesions of the thymus in a large case series in order to update the epidemiology, to improve diagnostic awareness, and finally to promote a collaborative network between referral centers.The thymus is a specialized primary lymphoid organ located in the midline pre-vascular mediastinum. The organ is the site of various pathological processes, neoplastic and not, whose rarity has not allowed in-depth studies on clinical or histological features of rarest and unusual variants. Herein, we report a 10-year Padova experience in the surgical pathology of the thymus, focusing on the pathological description of nonneoplastic lesions and rare epithelial and mesenchymal tumors recorded in our database, which comprises over 600 thymectomies. The extrapolated rare cases have been categorized into four groups that included 15 cysts, 18 carcinomas, 5 neuroendocrine tumors, and 2 soft tissue tumors. The cases are described from a clinical and pathological point of view and discussed in dedicated sections with a review of the most important literature. In this case, review series, we aim to update the epidemiology of these rare entities, improve diagnostic awareness, and finally, promote a collaborative network between referral centers.

Advancement in Diagnostic Imaging of Thymic Tumors.

Simple SummaryDiagnostic imaging is pivotal for the diagnosis and staging of thymic tumors. It is important to distinguish thymoma and other tumor histotypes amenable to surgery from lymphoma. Furthermore, in cases of thymoma, it is necessary to differentiate between early and advanced disease before surgery since patients with locally advanced tumors require neoadjuvant chemotherapy for improving survival. This review aims to provide to radiologists a full spectrum of findings of thymic neoplasms using traditional and innovative imaging modalities.Thymic tumors are rare neoplasms even if they are the most common primary neoplasm of the anterior mediastinum. In the era of advanced imaging modalities, such as functional MRI, dual-energy CT, perfusion CT and radiomics, it is possible to improve characterization of thymic epithelial tumors and other mediastinal tumors, assessment of tumor invasion into adjacent structures and detection of secondary lymph nodes and metastases. This review aims to illustrate the actual state of the art in diagnostic imaging of thymic lesions, describing imaging findings of thymoma and differential diagnosis.

Fat Content Quantification Using Dual-Energy CT for Differentiation of Anterior Mediastinal Lesions from Normal or Hyperplastic Thymus

BackgroundDetection of fat content in thymic lesions is crucial to differentiate thymic hyperplasia from thymic tumors or other anterior mediastinal pathologies. PurposeTo assess the feasibility of dual-energy CT (DECT) fat content quantification for the differentiation of anterior mediastinal lesions from benign thymic lesions and the normal spectrum of the thymus. Materials and MethodsChest DECT images of 465 patients (median 61 years, 63% female) were visually evaluated by two radiologists and semiquantitatively scored based on the degree of fatty degeneration ranging from completely fatty (score 0) to predominantly soft-tissue (score 3), and anterior mediastinal mass (score 4). A subset of scans (n =134 including all cases with scores 2-4 and 20 randomly-selected cases from scores 0 and 1) underwent quantitative DECT analysis (fat fraction, iodine density, and conventional CT value). DECT values were compared across the semiquantitative scores. ResultsResults of visual evaluation included 35 with predominantly solid thymus (score 3) and 15 with anterior mediastinal mass (score 4). The most common clinical diagnoses of the 15 masses (including 8 with pathologic confirmation) were metastases (n = 10) and lymphoma (n = 4). CT values in the abnormal thymus were significantly higher than those in score 3 (median: 69.7 HU versus 19.9 HU, P <0.001). There was no significant difference in iodine density values (median: 1.7 mg/ml versus 1 mg/ml, P = 0.09). However, the fat fraction value was significantly lower in the abnormal thymus (score 4) than in the predominantly soft-tissue attenuation thymuses (score 3) (median: 12.8% versus 38.7%, P <0.001). ROC curve analysis showed that fat fraction had an AUC of 0.96 (P <0.001), with a cutoff of <39.2% fat fraction yielding 100% sensitivity and 85% specificity. ConclusionDECT fat fraction measurements of the thymus may provide additional value in distinguishing anterior mediastinal lesions from benign thymus. Use of DECT may reduce the need for subsequent imaging evaluation.

English

BACKGROUND Mediastinal masses, an enigma to surgical pathologist are among the most complicated lesions explored and relatively inaccessible. They often connote a process with mass effect presenting with superior mediastinal syndrome. This is a challenging area faced by surgical pathologist as varied lesions are found here and often biopsies obtained are tiny and crushed. Appropriate therapy of various mediastinal tumours differs considerably and may significantly impact survival. We wanted to evaluate the various lesions in different compartments of mediastinum and categorise them according to anatomical location, and histopathology. METHODS Patients with mediastinal masses attending outpatient department were selected, history taken and relevant investigations done with radiological evaluation for proper anatomical location of lesion. Histopathological study done on tissues obtained by ultrasound / CT guided biopsy, open surgical biopsy were categorized according to histologic types. Immunohistochemistry was done wherever applicable. RESULTS A total of 58 cases of mediastinal lesions were studied where males predominated and age of patients ranged from 11 months to 68 yrs. All patients were symptomatic. Shortness of breath, superior vena cava syndrome was dominant in anterior and superior mediastinal lesions, middle and posterior mediastinal masses presented with chest pain. Most lesions were neoplastic. Germ cell tumours were found in (24.14 %) followed by lymphoma in (20.69 %) and thymic lesions in (18.97 %) of patients. Neurogenic tumours found in (13.79 %) were located in posterior mediastinum whereas, germ cell tumours and lymphomas were located in anterior mediastinum. Non neoplastic lesions included tuberculosis, sarcoidosis. Unsuspected lesion was metastatic deposit of adenoid cystic carcinoma. CONCLUSIONS A wide variety of non-neoplastic and neoplastic lesions can be found in different compartments of mediastinum and accurate diagnosis is considered necessary to formulate management strategies. KEYWORDS Mediastinum, Biopsy, Radiology, Histopathology

Successful surgical management of a rare combination of intrapericardial teratoma and thymoma in an infant

Primary cardiac tumors are rare, accounting for <0.2% of all childhood tumors. They can be diagnosed prenatally. Intrapericardial teratoma is a rare benign tumor that presents either due to the mass effect of the tumor or secondary pericardial effusion. Thymus is an important part of the immune system in the pediatric age group. Thymic lesions are rare causes of anterior mediastinal pathology. Their occurrence in children is rarer, nevertheless knowledge about their pathologies helps in clinching the correct diagnosis. We report a case of combined intrapericardial teratoma and thymoma that has not been reported previously in the literature.

The role of angiogenetic single-nucleotide polymorphisms in thymic malignancies and thymic benign lesions.

BackgroundWe previously showed that selected single-nucleotide-polymorphisms (SNPs) of genes involved in angiogenesis influence the aggressiveness of thymic epithelial tumors (TETs). This study analyzes their role in TETs and in thymic benign lesions, in order to investigate potential correlation with risk and outcome.MethodsGenomic DNA was extracted from paraffin-embedded tissue of 92 patients, undergoing surgery at our Institution. We investigated by Real-Time PCR the SNPs of the following genes: platelet-derived growth factor receptor-α (PDGFRα), hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor A (VEGF-A), vascular endothelial growth factor receptor-2 and 3 (VEGF-2, VEGFR-3), excision repair cross-complementation group-1 (ERCC1).ResultsFifty-seven TETs and 35 thymic benign lesions were included into the study. Frequency of SNPs was as follows: rs2057482 C, rs11158358 C and rs11549465 C polymorphisms of HIF1-a: thymomas < general population (P=0.008, P=0.007, and P=0.044 respectively). HIF1-a alleles: general population > study groups, rs1951795C SNP (P=0.026 for benign lesions and P=0.0007 for thymomas), rs10873142T SNP (P=0.008 and P=0.001 respectively), rs12434438 A SNP (P=0.034 and P=0.0007) and rs2301113A SNP (P=0.027 and P=0.010). rs699947C polymorphism of VEGF-A: benign lesions > general population (P=0.012).ConclusionsThis is the first study investigating the angiogenetic polymorphisms in thymic benign lesions and TETs. SNPs analysis may represent a further asset in identification of patients who could benefit from anti-angiogenetic therapy.

Detection of IgM and IgG Antibodies to Human Parvovirus B19 in Sera of Patients with Thymoma-Associated Myasthenia Gravis.

Much uncertainty still exists about the viral etiology of myasthenia gravis (MG). To address this, we explored the relationship between human parvovirus B19 (PVB19) infection and MG by investigating the presence of PVB19-specific antibodies in serum. A total of 131 patients with MG (including 47 with thymoma-associated MG, 14 with hyperplasia-associated MG, and 70 with unknown thymic lesions) and 172 healthy volunteers were enrolled in this study. Enzyme linked immunosorbent assay was conducted to detect virus-specific antibodies in cell-free serum. The data were analyzed using Pearson chi-square (χ2) and Fisher's exact tests. In the 131 patients with MG, there was no significant difference between male (53.41 ± 14.65 years) and female (50.19 ± 15.28 years) groups regarding mean age (p > 0.05). Among all MG subgroups, the largest age group comprised participants aged 30-60 years. We found that the frequency of detecting immunoglobulin G (IgG) antibodies against PVB19 VP1 and VP2 was significantly higher among patients with MG (68.70%) than in healthy controls (41.86%) (p < 0.001). In particular, the positive rate for anti-PVB19 IgG in patients with thymoma-associated MG (35/47, 74.47%) was significantly higher than that in healthy participants (72/172, 41.86%; p < 0.001). The findings of this study indicate that PVB19 infection may play a role in the etiopathogenesis of MG, particularly in patients with thymoma-associated MG. The study protocol was registered at ClinicalTrials.gov with the identifier ChiCTR-1900023338.

Metabolic Characterization of Anterior Mediastinal Masses by 18F-FDG PET/CT

Objectives:To evaluate the role of 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for the diagnosis of anterior mediastinal masses.Methods:The oncological 18F-FDG PET/CT images of 41 patients (17 women, 24 men; age: 16-83 years, mean age: 50.5±19.5 years) who attended the nuclear medicine department between November 2016 and September 2017 were retrospectively evaluated for the metabolic characterization of their anterior mediastinal masses.Results:Based on our results, the lesions of 4 patients were benign [maximum standard uptake value (SUVmax) <3] and that of 2 patients were non-tumoral (i.e., tuberculosis and sarcoidosis). The mean dimensions and the SUVmax levels of the malignant lesions were 6.4±3.7 cm and 11.9±9.6, respectively. The pathological results for the malign tumors were thymus tumors (n=8), lymphoma (n=8), lung cancer (n=11), carcinoid metastasis (n=2), thyroid carcinoma (n=2), germ cell carcinoma (n=1), schwannoma (n=1), and sarcoma (n=1). The degree of 18F-FDG accumulation could precisely identify the malign and benign tumors.Conclusion:Thus, contrary to the known causes, it is possible that anterior mediastinal masses originate from structures other than the anterior mediastinal structures. In this study, the lymphoma and lung carcinoma pathology were more frequent than thymic lesions.

Interobserver variation in the classification of thymic lesions including biopsies and resection specimens in an international digital microscopy panel.

AimsThymic tumours are rare in routine pathology practice. Although the World Health Organization (WHO) classification describes a number of well‐defined categories, the classification remains challenging. The aim of this study was to investigate the reproducibility of the WHO classification among a large group of international pathologists with expertise in thymic pathology and by using whole slide imaging to facilitate rapid diagnostic turnover.Methods and resultsThree hundred and five tumours, consisting of 90 biopsies and 215 resection specimens, were reviewed with a panel‐based virtual microscopy approach by a group of 13 pathologists with expertise in thymic tumours over a period of 6 years. The specimens were classified according to the WHO 2015 classification. The data were subjected to statistical analysis, and interobserver concordance (Fleiss kappa) was calculated. All cases were diagnosed within a time frame of 2 weeks. The overall level of agreement was substantial (κ = 0.6762), and differed slightly between resection specimens (κ = 0.7281) and biopsies (κ = 0.5955). When analysis was limited to thymomas only, and they were grouped according to the European Society for Medical Oncology Clinical Practice Guidelines into B2, B3 versus A, AB, B1 and B3 versus A, AB, B1, B2, the level of agreement decreased slightly (κ = 0.5506 and κ = 0.4929, respectively). Difficulties arose in distinguishing thymoma from thymic carcinoma. Within the thymoma subgroup, difficulties in distinction were seen within the B group.ConclusionsAgreement in diagnosing thymic lesions is substantial when they are assessed by pathologists with experience of these rare tumours. Digital pathology decreases the turnaround time and facilitates access to what is essentially a multinational resource. This platform provides a template for dealing with rare tumours for which expertise is sparse.

Celastrol Efficacy by Oral Administration in the Adjuvant-Induced Arthritis Model.

Background: We previously demonstrated that celastrol has significant anti-inflammatory and bone protective effects when administered via the intraperitoneal route. For further preclinical evaluation, an effective oral administration of celastrol is crucial. Here we aimed to study the therapeutic dose range for its oral administration.Methods: Celastrol (1–25 μg/g/day, N = 5/group) was administrated orally to female adjuvant-induced arthritis (AIA) rats after 8 days of disease induction for a period of 14 days. A group of healthy (N = 8) and arthritic (N = 15) gender- and age-matched Wistar rats was used as controls. During the treatment period, the inflammatory score, ankle perimeter, and body weight were measured. At the end of the treatment, the animals were sacrificed, blood was collected for clinical pathology, necropsy was performed with collection of internal organs for histopathological analysis, and paw samples were used for disease scoring.Results: Doses higher than 2.5 μg/g/day of celastrol reduced the inflammatory score and ankle swelling, preserved joint structure, halted bone destruction, and diminished the number of synovial CD68+ macrophages. Bone resorption and turnover were also reduced at 5 and 7.5 μg/g/day doses. However, the dose of 7.5 μg/g/day was associated with thymic and liver lesions, and higher doses showed severe toxicity.Conclusion: Oral administration of celastrol above 2.5 μg/g/day ameliorates arthritis. This data supports and gives relevant information for the development of a preclinical test of celastrol in the setting of a chronic model of arthritis since rheumatoid arthritis is a long-term disease.

Role of different imaging modalities in the evaluation of normal and diseased thymus

BackgroundThe appearance of the thymus on imaging studies showed great variability. Thymus imaging is a great challenge. This cross-sectional prospective study investigated the diagnostic value of different imaging modalities in the evaluation of normal and diseased thymus. Chest X-ray was done as a primary survey. Chest computed tomography (CT) was done for 82 patients, chest magnetic resonant imaging (MRI) was done for 40 patients, and 18 flurodeoxy glucose positron emission tomography (18 FDG-PET) was done for 2 patients. Ultrasonography (US) of the anterior mediastinum was done for 2 pediatric patients. Histopathological assessment was done for all cases with diseased thymus.ResultsThe study included 158 patients divided into 2 groups: group A, 79 patients with normal thymus for age and group B, 79 patients with thymic lesions detected by one or more of the used modalities. The large-sized thymus was in 79 patients, who were subcategorized to patients with myasthenia gravis (12 patients) and patients with mediastinal masses (67 patients). Imaging findings in normal and diseased thymus gland were compared and lesion analysis by various modalities displayed with histopathological correlation.ConclusionThere are different imaging modalities for thymus gland evaluation. CT is beneficial for primary assessment giving the morphology and density, and MRI is the imaging modality of choice in diseased thymus owing to functional assessment of the gland; however, X-ray may be helpful as a primary survey tool before CT and MRI. Chest ultrasound could be a suitable primary assessment tool in pediatrics before MRI because it is an easy bedside test.

Immunological and pathological adverse effects of avian influenza virus subtype H9N2 infection in aflatoxicated-broiler chickens

Aflatoxin B1 (AFB1) is a metabolic product of the Aspergillus spp. of molds, which grow on several feedstuffs stored in hot moist conditions. It is one of the immunosuppressive agents that might influence the pathogenesisof avian influenza virus (AIV) subtype H9N2 in broilers, which can exacerbate the disease outcomes. The immunological, biochemical and pathological adverse health effects of an interaction between low levels of dietary aflatoxins (AFs) and H9N2 infection in broiler chickens were investigated. One hundred and eighty of unvaccinated 1-day-old COBB chicks were, therefore, raised for 35 days in the following treatment groups: control, AFs, AFs+H9N2, and H9N2. AFs in the basal diet was added at 200 ppb starting from the first day of age, while H9N2 virus was intra-nasally installed at a dose of 100 μl of 106 EID50/bird of allantois fluid at 23rd day. Humoral and cell-mediated immune responses were evaluated. Evidence of H9N2-AIV viral shedding was also detected. It has been observed that concurrent exposure of AFs and H9N2 virus negatively affected chicken performance traits i.e. lowered feed intake and body weights with exaggerated respiratory and digestive disturbances, and 20% mortality rate. Ten days’ post H9N2 infection, significant (p≤ 0.05) increment in serum transaminases (AST and ALT) and falling in cell-mediated immunity i.e. total leukocyte count, lymphocyte transformation activity and macrophage phagocytic activity were detected. Additionally, AFs+H9N2 significantly (p≤ 0.05) lowered H9N2-HI titers (5.5 Log2) than H9N2 alone (6.3 Log2). Pathologically, aflatoxicated chickens showed hydropic degeneration, hepatocytic vacuolation and necrosis of liver tissues with nephrosis and urates deposition in ureters, as well as bursal and thymic lesions, which were potent in H9N2–inoculated chickens. AFs exposure increased the incidence and titer of H9N2 viral shedding. It could be concluded that dietary contamination with AFs even at very low levels has explanatory effect in H9N2–inoculated broilers, and vice versa.

Pitfalls of FNA diagnosis of thymic tumors.

Fine-needle aspiration (FNA), a minimally invasive and cost-effective procedure, often is used in the initial diagnosis of thymic lesions. However, the diagnosis can be challenging. Knowledge of the diagnostic pitfalls is important to improve diagnostic accuracy. The authors retrospectively searched the pathology database of The University of Texas MD Anderson Cancer Center for FNA cases using the keywords "thymoma" or "thymic" in cytologic diagnoses or in corresponding final histologic diagnoses rendered from January 2002 to June 2018. The authors reviewed the FNA diagnostic accuracy and pitfalls in comparison with the final histologic diagnoses. A total of 118 FNA cases were identified from 115 patients. The FNA diagnoses were concordant with the final pathologic diagnoses in 110 cases (93.2%), including thymoma (97 cases), atypical thymoma (5 cases), and thymic carcinoma (8 cases). Discrepant FNA and final diagnoses were noted in 8 tumors (6.8%): thymoma versus atypical thymoma/thymic carcinoma (3 tumors), thymoma versus lymphoma (2 tumors), suspicious for lymphoma versus thymoma (1 tumor), and T-lymphoblastic lymphoma versus thymoma (2 tumors). Factors contributing to misinterpretation included intrinsic limitations of the FNA sample (sampling error and a lack of histologic architecture information) and similarities of the cytologic and immunophenotypic features of lymphocyte-rich thymoma and T-lymphoblastic lymphoma. An accurate FNA diagnosis of thymic tumors can be rendered in the majority of cases. Diagnostic pitfalls can be encountered in rare cases. It is important to handle each case carefully to avoid erroneous diagnoses that may lead to inappropriate treatment.

Errors in Interpretation of Magnetic Resonance Imaging for Thymic Lesions.

The objectives of this study were to evaluate the magnetic resonance imaging (MRI) features of thymic lesions and to review those features that may result in diagnostic uncertainty or error. This multicenter retrospective study included patients with pathologically proven thymic epithelial neoplasms (TEN) and thymic cysts who underwent preoperative MRI. Clinical reports were evaluated for the radiologist's first-choice diagnosis, if not already known before the MRI. MR images were reviewed by thoracic radiologists to identify cystic components on T2-weighted imaging (T2WI) as well as the presence of enhancement on postcontrast series. Through a search of electronic medical records of 3 tertiary academic medical centers, we identified 41 TEN and 13 cysts. Of 35 evaluable clinical reports, 9 (26%) gave an incorrect diagnosis. Of these, 5 cases were misdiagnosed related to contrast enhancement, and 3 cases of cysts were misdiagnosed because of lack of fluid signal on T2WI. Upon rereview of images, of the 41 TENs, 4 (10%) did not show qualitative enhancement on the first postcontrast phase (although all enhanced eventually), and 4 cysts (31%) did not show fluid signal on T2WI. In addition, 4 cases of cysts (31%) showed mural or septal enhancement. Although atypical or misleading imaging features are uncommon in TEN and thymic cysts, they do occur and may lead to diagnostic error. We suggest that lesions with a T2 signal less than simple fluid and without enhancement on postcontrast images undergo follow-up imaging to confirm a benign diagnosis.