Our experience with robotic-assisted thymic surgery.

Thoracic surgery is increasingly influenced by the development of minimally invasive approaches which have also influenced surgery in the area of the anterior mediastinum. The previously standard approach to the thymus via partial sternotomy was gradually replaced by the videothoracoscopic approach in most cases. In recent years, robotically assisted surgery has been gaining ground worldwide in this area, as well. The aim of our paper is to provide a comprehensive overview of procedures in the field of the thymus, including their indications, and to share our first experience with robot-assisted thymus surgery. At the 3rd Department of Surgery, since the start of the robot-assisted thymus surgery program, 23 thymectomies have been performed using this approach, of which 17 were performed for thymoma, 3 for myasthenia gravis, and 3 for parathyroid adenoma localized in thymus tissue. From our experience and the available data, it follows that the length of hospitalization, the rate of complications and the resulting effect of robot-assisted procedures is comparable to VTS procedures; however, the robot-assisted surgery also allows for mini-invasive treatment even in significantly obese patients and in patients with advanced thymic tumors who would otherwise be indicated for open thymectomy.

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.

T cell phenotype in paediatric heart transplant recipients.

Paediatric heart transplantation recipients suffer an increased incidence of infectious, autoimmune and allergic problems. The relative roles of thymus excision and immunosuppressive treatments in contributing to these sequelae are not clear. We compared the immunological phenotypes of 25 heart transplant recipients (Tx), 10 children who underwent thymus excision during non-transplantation cardiac surgery (TE) and 25 age range-matched controls, in two age bands: 1-9 and 10-16 years. Significant differences from controls were seen mainly in the younger age band with Tx showing lower CD3 and CD4 cell counts whilst TE showed lower CD8 cell counts. Naïve T cell and recent thymic emigrant proportions and counts were significantly lower than controls in both groups in the lower age band. T cell recombination excision circle (TREC) levels were lower than controls in both groups in both age bands. There were no differences in regulatory T cells, but in those undergoing thymus excision in infancy, their proportions were higher in TE than Tx, a possible direct effect of immunosuppression. T cell receptor V beta spectratyping showed fewer peaks in both groups than in controls (predominantly in the older age band). Thymus excision in infancy was associated with lower CD8 cell counts and higher proportions of Tregs in TE compared to Tx. These data are consistent with thymus excision, particularly in infancy, being the most important influence on immunological phenotype after heart transplantation.

Quantitative Histogram Analysis of T2-Weighted and Diffusion-Weighted Magnetic Resonance Images for Prediction of Malignant Thymic Epithelial Tumors.

PURPOSE: To assess the value of histogram analysis for differentiating a high-risk thymic epithelial tumor (TET) from a low-risk TET using T2-weighted images and the apparent diffusion coefficient (ADC). METHODS: Forty-nine patients with histopathologically proven TET after thymectomy were enrolled in this study and retrospectively classified as having low-risk TET (low-risk thymoma) or high-risk TET (high-risk thymoma or thymic carcinoma). Twelve parameters were obtained from the quantitative histogram analysis. The histogram parameters were compared using the Mann-Whitney U test. Diagnostic efficacy was estimated by receiver-operating characteristic curve analysis. RESULTS: Twenty-five patients were classified as having low-risk TET and 24 as having high-risk TET. The mean ADC value showed diagnostic efficacy for differentiating high-risk TET from low-risk TET, with an area under the curve of 0.7, and was better than when using conventional methods alone. CONCLUSION: The ADC-based histogram analysis could help to differentiate between high-risk and low-risk TETs.

The Value of CT and MRI for Determining Thymoma in Patients With Myasthenia Gravis.

The aim of the study was to evaluate the usefulness of computed tomography (CT) and magnetic resonance imaging (MRI) for differentiating thymoma from nonthymoma abnormalities in patients with myasthenia gravis (MG). A cross-sectional study of 53 patients with MG, who had undergone surgical thymectomy, was conducted at 103 Hospital (Hanoi, Vietnam) and Cho Ray Hospital (Ho Chi Minh City, Vietnam) during August 2014 and January 2017. The CT and MRI images of patients with MG were qualitatively and quantitatively (radiodensity and chemical shift ratio [CSR]) analyzed to determine and compare their ability to distinguish thymoma from nonthymoma abnormalities. Logistic regression was used to identify the association between imaging parameters (eg, CSR) and the thymoma status. The receiver operating curve (ROC) analysis was used to determine the differentiating ability of CSR and radiodensity. As results, of the 53 patients with MG, 33 were with thymoma and 20 were with nonthymoma abnormalities. At qualitative assessment, MRI had significantly higher accuracy than did CT in differentiating thymoma from nonthymoma abnormalities (94.3% vs 83%). At quantitative assessment, both the radiodensity and CSR were significantly higher for thymoma compared with nonthymoma groups (P < .001). The ROC analysis showed that CSR had significantly higher sensitivity (Se) and specificity (Sp) than radiodensity in discriminating between the 2 groups (CSR: Se 100%, Sp 95% vs radiodensity: Se 90.9%, Sp 70%). When combining both qualitative and quantitative parameters, MRI had even higher accuracy than did CT in thymoma diagnosis (P = .031). In conclusion, chemical shift MRI was more accurate than CT for differentiating thymoma from nonthymoma in patients with MG.

Testosterone Protects Against Atherosclerosis in Male Mice by Targeting Thymic Epithelial Cells-Brief Report.

OBJECTIVE: Androgen deprivation therapy has been associated with increased cardiovascular risk in men. Experimental studies support that testosterone protects against atherosclerosis, but the target cell remains unclear. T cells are important modulators of atherosclerosis, and deficiency of testosterone or its receptor, the AR (androgen receptor), induces a prominent increase in thymus size. Here, we tested the hypothesis that atherosclerosis induced by testosterone deficiency in male mice is T-cell dependent. Further, given the important role of the thymic epithelium for T-cell homeostasis and development, we hypothesized that depletion of the AR in thymic epithelial cells will result in increased atherosclerosis. APPROACH AND RESULTS: Prepubertal castration of male atherosclerosis-prone apoE-/- mice increased atherosclerotic lesion area. Depletion of T cells using an anti-CD3 antibody abolished castration-induced atherogenesis, demonstrating a role of T cells. Male mice with depletion of the AR specifically in epithelial cells (E-ARKO [epithelial cell-specific AR knockout] mice) showed increased thymus weight, comparable with that of castrated mice. E-ARKO mice on an apoE-/- background displayed significantly increased atherosclerosis and increased infiltration of T cells in the vascular adventitia, supporting a T-cell-driven mechanism. Consistent with a role of the thymus, E-ARKO apoE-/- males subjected to prepubertal thymectomy showed no atherosclerosis phenotype. CONCLUSIONS: We show that atherogenesis induced by testosterone/AR deficiency is thymus- and T-cell dependent in male mice and that the thymic epithelial cell is a likely target cell for the antiatherogenic actions of testosterone. These insights may pave the way for new therapeutic strategies for safer endocrine treatment of prostate cancer.

Microdeletion 22q11.2 syndrome: Does thymus incidental surgical resection affect its immunological profile?

BACKGROUND: The del22q11 syndrome patients present immunological abnormalities associated to thymus alterations. Up to 75% of them present cardiopathies and thymus is frequently removed during surgery. The thymectomy per se has a deleterious effect concerning lymphocyte subpopulations, and T cell function. When compared to healthy controls, these patients have higher infections propensity of variable severity. The factors behind these variations are unknown. We compared immunological profiles of del22q11.2 Syndrome patients with and without thymectomy to establish its effect in the immune profile. METHODS: Forty-six del22q11.2 syndrome patients from 1 to 16 years old, 19 of them with partial or total thymectomy were included. Heart disease type, heart surgery, infections events and thymus resection were identified. Immunoglobulin levels, flow cytometry for lymphocytes subpopulations and TREC levels were determined, and statistical analyses were performed. RESULTS: The thymectomy group had a lower lymphocyte index, both regarding total cell count and when comparing age-adjusted Z scores. Also, CD3+, CD4+ and CD8+ lower levels were observed in this group, the lowest count in those patients who had undergone thymus resection during the first year of life. Their TREC level median was 23.6/µL vs 16.1µL in the non-thymus group (p=0.22). No differences were identified regarding immunoglobulin levels or infection events frequencies over the previous year. CONCLUSION: Patients with del22q11.2 syndrome subjected to thymus resection present lower lymphocyte and TREC indexes when compared to patients without thymectomy. This situation may be influenced by the age at the surgery and the time elapsed since the procedure.

Dosimetric comparison of advanced radiotherapy approaches using photon techniques and particle therapy in the postoperative management of thymoma.

BACKGROUND: The purpose of this study was to compare dosimetric differences related to target volume and organs-at-risk (OAR) using 3D-conformal radiotherapy (3DCRT), volumetric modulated arc therapy (VMAT), TomoTherapy (Tomo), proton radiotherapy (PRT), and carbon ion radiotherapy (CIRT) as part of postoperative thymoma irradiation. MATERIAL AND METHODS: This single-institutional analysis included 10 consecutive patients treated with adjuvant radiotherapy between December 2013 and September 2016. CT-datasets and respective RT-structures were anonymized and plans for all investigated RT modalities (3DCRT, VMAT, Tomo, PRT, CIRT) were optimized for a total dose of 50 Gy in 25 fractions. Comparisons between target volume and OAR dosimetric parameters were performed using the Wilcoxon rank-sum test. RESULTS: The best target volume coverage (mean PTV V95% for all patients) was observed for Tomo (97.9%), PRT (97.6%), and CIRT (96.6%) followed by VMAT (85.4%) and 3DCRT (74.7%). PRT and CIRT both significantly reduced mean doses to the lungs, breasts, heart, and esophagus, as well as the spinal cord maximum dose compared with photon modalities. Among photon-based techniques, VMAT showed improved OAR sparing over 3DCRT. Tomo was associated with considerable low-dose exposure to the lungs, breasts, and heart. CONCLUSIONS: Particle radiotherapy (PRT, CIRT) showed superior OAR sparing and optimal target volume coverage. The observed dosimetric advantages are expected to reduce toxicity rates. However, their clinical impact must be investigated prospectively.

PD-L1 immuno-expression assay in thymomas: Study of 84 cases and review of literature.

BACKGROUND AND AIMS: Programmed death ligand 1 (PD-L1), an immune check point inhibitor, is known to be expressed in several malignancies and is being considered as a prognostic factor and a potential immunotherapeutic target. The aim of this study was to characterize PD-L1 expression in thymomas and to determine correlation with clinicopathological features and previously published studies in the literature. METHODS: Tissue microarrays were prepared from selected blocks of thymomas and immunohistochemistry (IHC) for PD-L1 was performed. Cases were considered as PD-L1 positive or negative depending on whether the percentage of stained thymic epithelial cells were <25 or >25%. Results were compared clinically and with previously published studies using Google and Pubmed search engines. RESULTS: Of 84 cases of thymoma, 69 (82.1%) revealed PD-L1 positivity in >25% cells. 94.23% of type B thymoma subtypes (B1/B2/B3) were PD-L1 positive (P < 0.001). There was no correlation of PD-L1 with age, gender, myasthenia gravis, the tumor size or stage of disease. Nine studies were available in the literature; most of which showed PD-L1 expression in higher stage and B subtype however percentage positivity varied from 53.7% to over 90%. CONCLUSIONS: PD-L1 expression is frequent in type B (B1/B2/B3) thymomas. It can be easily evaluated by IHC even on small biopsies in unresectable cases, thereby enabling improved clinical evaluation as well as prognostic stratification of patients. It will serve as a potential indicator for benefit from anti-PD-L1 antibody immunotherapy in thymomas.

[Video-assisted thoracoscopic thymectomy in myasthenia gravis. New approach]. / Videoassistirovannaia torakoskopicheskaia timéktomiia pri miastenii. Novyi podkhod.

AIM: To present possibility and technical aspects of anesthetic management during video-assisted thoracoscopic thymectomy in patients with myasthenia gravis. MATERIAL AND METHODS: The article describes the proposed modified anesthetic method that is suitable for video-assisted thoracoscopic thymectomy in patients with myasthenia gravis. Nine patients with myasthenia underwent VATS-thymectomy. Anesthesia was performed with artificial airway and auxiliary ventilation without muscle relaxants administration.

Robust gene expression changes in the ganglia following subclinical reactivation in rhesus macaques infected with simian varicella virus.

Varicella zoster virus (VZV) causes varicella during acute infection and establishes latency in the sensory ganglia. Reactivation of VZV results in herpes zoster, a debilitating and painful disease. It is believed that VZV reactivates due to a decline in cell-mediated immunity; however, the roles that CD4 versus CD8 T cells play in the prevention of herpes zoster remain poorly understood. To address this question, we used a well-characterized model of VZV infection where rhesus macaques are intrabronchially infected with the homologous simian varicella virus (SVV). Latently infected rhesus macaques were thymectomized and depleted of either CD4 or CD8 T cells to induce selective senescence of each T cell subset. After T cell depletion, the animals were transferred to a new housing room to induce stress. SVV reactivation (viremia in the absence of rash) was detected in three out of six CD8-depleted and two out of six CD4-depleted animals suggesting that both CD4 and CD8 T cells play a critical role in preventing SVV reactivation. Viral loads in multiple ganglia were higher in reactivated animals compared to non-reactivated animals. In addition, reactivation results in sustained transcriptional changes in the ganglia that enriched to gene ontology and diseases terms associated with neuronal function and inflammation indicative of potential damage as a result of viral reactivation. These studies support the critical role of cellular immunity in preventing varicella virus reactivation and indicate that reactivation results in long-lasting remodeling of the ganglia transcriptome.

Effect of IL-7 Therapy on Naive and Memory T Cell Homeostasis in Aged Rhesus Macaques.

Aging is associated with gradual deterioration of adaptive immune function, a hallmark of which is the profound loss of naive T cells (TN) associated with decline in thymic output and export of new cells into the peripheral T cell pool. Because the lymphotropic cytokine IL-7 plays crucial roles in both development of TN in the thymus and TN homeostasis in the periphery, we sought to determine the extent to which therapeutic administration of IL-7 could reverse TN deficiency in aging rhesus macaques (RM), either by enhancement of the demonstrably reduced thymopoiesis or by peripheral TN expansion. Our results indicate that treatment of both adult (8-15 y) and old (>20 y) RM with recombinant simian IL-7 (rsIL-7) results in only transient increases in peripheral CD4(+) and CD8(+) TN numbers with no long-term benefit, even with repeated therapy. This transient effect was due to peripheral TN expansion and not enhanced thymic function, and appeared to be limited by induction of IL-7 nonresponsiveness. However, rsIL-7 therapy had a more promising effect on the central memory T cell (TCM) population (both CD4(+) and CD8(+)) in adult and old RM, doubling the numbers of these cells in circulation and maintaining this larger population long term. IL-7 therapy did not reduce TCR diversity of the memory T cell compartment, suggesting that rsIL-7-induced expansion was symmetrical. Thus, although rsIL-7 failed to counter age-associated TN loss, the ability of this therapy to expand clonotypically diverse CD4(+) and CD8(+) TCM populations might potentially improve adaptive immune responsiveness in the elderly.

Experience using closed incision negative pressure wound therapy in sternotomy patients.

OBJECTIVE: Postoperative delayed wound healing, surgical site infections (SSIs), and other wound complications are associated with increased morbidity and health-care costs. In cardiothoracic surgery, wound complications can have life-threatening consequences. In recent years, negative pressure wound therapy (NPWT) has been applied over closed surgical incisions to help reduce tension and protect from external contamination. We report our initial experiences using a closed incision negative pressure therapy (ciNPT) over clean, closed sternotomy incisions at an Irish tertiary referral centre. METHOD: A retrospective record review identified 10 patients (4 females, 6 males) where ciNPT was used following sternotomy for cardiac surgery or other mediastinal surgery between January 2012 and March 2013. RESULTS: The patients had an average age of 71.5±14.18 years (range: 44-89 years). Patient comorbidities included obesity, hypertension, active tobacco use, chronic obstructive pulmonary disease, and diabetes mellitus. Patients underwent coronary artery bypass grafting (CABG), aortic valve replacement (AVR), AVR and CABG, or removal of a thymic mass or mediastinal cyst. ciNPT was left in place for an average of 6±0.82 days. All incisions healed without complications. CONCLUSION: ciNPT use should be considered for patients at risk for postoperative SSI development or other wound complications.

Expression of receptor for advanced glycation end-products (RAGE) in thymus from myasthenia patients.

OBJECTIVES: The receptor for advanced glycation end-products (RAGE) is a membranous immunoglobulin involved in the pathogenesis of numerous autoimmune diseases and tumors. The aim of this study was to investigate the possible involvement of RAGE in the pathogenesis of myasthenia gravis. MATERIAL AND METHODS: This prospective study included 41 cases of myasthenia gravis treated at our institution between 2010 and 2015. There were 18 men and 23 women, with an average age of 36.44±14.47 years. The majority of patients (24.4%) were classified as IIb, according to MGFA scoring, and 21 of them required corticosteroid and/or immunosuppressive treatment. Assessment of RAGE in thymus specimens was done by immunohistochemistry using RAGE antibody (C-term). RAGE expression was assessed according to various clinical, paraclinical and pathological parameters. RESULTS: Histopathological studies found 18 thymomas, 17 hyperplasias and six other types of pathology. Expression of RAGE was negative/weak in 19 cases and moderate/strong in 22 cases. It was more important in thymoma type B2 (P<0.001) and when the duration of myasthenia was short (P=0.04), and was not significantly related to either myasthenia clinical severity or preoperative treatment. CONCLUSION: Our results suggest that the RAGE pathway is involved in myasthenia gravis pathophysiology, especially at disease onset, and in forms with thymomas. Further studies would be indispensable to explore other aspects of this signaling pathway, especially the potential role of different ligands and soluble forms of RAGE.

Analysis of mortality and related factors in 2195 adult myasthenia gravis patients in a 10-year follow-up study.

OBJECTIVE: To analyze the mortality and potential risk factors for death in myasthenia gravis (MG) patients. MATERIALS AND METHODS: A total of 2195 adult patients with MG (aged older than 18 years) diagnosed during the period between 2003 and 2013 were followed-up and retrospectively reviewed. RESULTS: During the 10-year follow-up, 129 patients died and the total mortality rate was 5.88%. The risk factors associated with MG-related deaths were duration of the disease, occurrence of myasthenic crisis, severity of disease that included the Myasthenia Gravis Foundation of America (MGFA) grade III and IV at onset, elevation of acetylcholine receptor antibody (AchR-abs) titers, presence of thymic pathology, and failure of administrating immunosuppressants (P < 0.05). In addition, the non-MG related factors, including the history of preceding strokes, and the presence of chronic obstructive pulmonary disease (COPD), diabetes mellitus, atrial fibrillation, hyperlipidemia, myocardial infarction, and malignant tumors, were closely linked with death in the MG population (the hazard ratios [HRs] were 3.251, 4.173, 3.738, 3.886, 1.945, 2.177, and 14.7, respectively; P< 0.05). CONCLUSIONS: The severity of disease at entry, presence of AchRabs, thymic pathology, and duration of the disease predict a higher risk for death. Systemic illnesses including stroke, COPD, diabetes mellitus, atrial fibrillation, hyperlipidemia, myocardial infarction, and malignant tumor, which may also increase the risk of death, should be carefully monitored and managed.

Ocular Myasthenia Gravis Associated With Thymic Amyloidosis.

A 45-year-old woman with ptosis and diplopia was found to have myasthenia gravis (MG) associated with amyloidosis of the thymus gland. Systemic MG is frequently associated with thymomas or thymic hyperplasia but has only once previously been reported in association with amyloidosis of the thymus. This case demonstrates that isolated ocular MG rarely may also be associated with amyloidosis of the thymus.

Multidisciplinary treatment for prepubertal juvenile myasthenia gravis with crisis.

The management of juvenile myasthenia gravis (MG) remains controversial. We report herein the case of a 12-year-old girl with prepubertal juvenile MG with respiratory crisis who underwent thymectomy following methylprednisolone pulse therapy. The patient initially developed progressively worsening fatigability, eyelid ptosis, and diplopia, followed by worsening generalized weakness, dysphagia, and dyspnea. Even after i.v. immunoglobulin, the patient presented with rapid onset of severe dyspnea requiring respiratory support with mechanical ventilation and was graded as Myasthenia Gravis Foundation of America class V. After a course of i.v. methylprednisolone pulse therapy, successful control of respiratory crisis was achieved, and trans-sternal thymectomy was performed. Partial remission was achieved postoperatively with oral pyridostigmine without immunosuppressive agents such as steroids or calcineurin inhibitors for 18 months after thymectomy. Early thymectomy following induction methylprednisolone pulse therapy might be a treatment option for prepubertal juvenile MG with severe respiratory crisis.

Effect of thymic stimulation of CD4+ T cell expansion on disease onset and progression in mutant SOD1 mice.

BACKGROUND: The peripheral immune system is implicated in modulating microglial activation, neurodegeneration and disease progression in amyotrophic lateral sclerosis (ALS). Specifically, there is reduced thymic function and regulatory T cell (Treg) number in ALS patients and mutant superoxide dismutase 1 (SOD1) mice, while passive transfer of Tregs ameliorates disease in mutant SOD1 mice. Here, we assessed the effects of augmenting endogenous CD4+ T cell number by stimulating the thymus using surgical castration on the phenotype of transgenic SOD1(G93A) mice. METHOD: Male SOD1(G93A) mice were castrated or sham operated, and weight loss, disease onset and progression were examined. Thymus atrophy and blood CD4+, CD8+ and CD4+ FoxP3+ T cell numbers were determined by fluorescence activated cell sorting (FACS). Motor neuron counts, glial cell activation and androgen receptor (AR) expression in the spinal cord were investigated using immunohistochemistry and Western blotting. Differences between castrated and sham mice were analysed using an unpaired t test or one-way ANOVA. RESULTS: Castration significantly increased thymus weight and total CD4+ T cell numbers in SOD1(G93A) mice, although Tregs levels were not affected. Despite this, disease onset and progression were similar in castrated and sham SOD1(G93A) mice. Castration did not affect motor neuron loss or astrocytic activation in spinal cords of SOD1(G93A) mice; however, microglial activation was reduced, specifically M1 microglia. We also show that AR is principally expressed in spinal motor neurons and progressively downregulated in spinal cords of SOD1(G93A) mice from disease onset which is further enhanced by castration. CONCLUSIONS: These results demonstrate that increasing thymic function and CD4+ T cell number by castration confers no clinical benefit in mutant SOD1 mice, which may reflect an inability to stimulate neuroprotective Tregs. Nonetheless, castration decreases M1 microglial activation in the spinal cord without any clinical improvement and motor neuron rescue, in contrast to other approaches to suppress microglia in mutant SOD1 mice. Lastly, diminished AR expression in spinal motor neurons, which links to another motor neuron disorder, spinal bulbar muscular atrophy (SBMA), may contribute to ALS pathogenesis and suggests a common disease pathway in ALS and SBMA mediated by disruption of AR signalling in motor neurons.

Value of Prophylactic Cervical Thymectomy in Parathyroid Hyperplasia.

BACKGROUND: In parathyroid hyperplasia (HPT), parathyroid glands within the cervical thymus are a cause for recurrence. As a result of differences in pathophysiology, variable practice patterns exist regarding performing bilateral cervical thymectomy (BCT) in primary hyperplasia versus hyperplasia from renal failure or familial disease. The objective of this study was to capture patients where thymic tissue was found with subtotal parathyroidectomy (PTX) and intended BCT, identify number of thymic supernumerary glands (SNGs), and determine overall cure rate. METHODS: Retrospective review of patients with four-gland exploration and intended BCT for HPT from 2000 to 2013 was performed. Identification of thymic tissue and SNGs were determined by operative/pathology reports. Univariate analysis identified differences in cure rate for patients undergoing subtotal PTX with or without BCT. RESULTS: Thymic tissue was found in 52 % of 328 primary HPT (19 % unilateral, 33 % bilateral), 77 % of 128 renal HPT (28 % unilateral, 49 % bilateral), and 100 % of familial HPT (24 % unilateral, 76 % bilateral) patients. Nine percent of primary, 18 % of renal, and 10 % of familial HPT patients had SNGs within thymectomy specimens. Cure rates of primary HPT patients with BCT were 99 % compared to 94 % in subtotal PTX alone. Renal HPT cure rates were 94 % with BCT compared to 89 % without BCT. CONCLUSIONS: Renal HPT patients benefited most in cure when thymectomy was performed. Although the rate of SNGs found in primary HPT was lower than renal HPT, the cure rate mimicked the pattern in renal disease. Furthermore, the incidences of SNGs in primary and familial HPT were similar. On the basis of these data, we advocate that BCT be considered in primary HPT when thymic tissue is readily identified.