Diagnosis Of Anterior Mediastinal Masses Research Articles

Thymic Parenchymal Hyperplasia

Thymic hyperplasia is a rare condition generally caused by lymphoid follicular hyperplasia associated with autoimmune disorders. True thymic parenchymal hyperplasia unassociated with lymphoid follicular hyperplasia is extremely rare and may give rise to difficulties in diagnosis. We have studied 44 patients with true thymic hyperplasia (38 females and 6 males) aged 7 months to 64 years (mean, 36 years). Eighteen patients presented with symptoms of chest discomfort or shortness of breath; in 20 patients, the lesions were discovered incidentally. Imaging studies demonstrated enlargement of the mediastinum by a mass lesion suspicious for malignancy. All patients were treated with complete surgical excision. The tumors measured from 3.5 to 24 cm (median, 10 cm; mean, 10.46 cm). Histologic examination showed lobules of thymic tissue displaying well-developed corticomedullary architecture, with scattered Hassall corpuscles separated by mature adipose tissue and bounded by a thin fibrous capsule. No cases showed evidence of lymphoid follicular hyperplasia, cytologic atypia, or confluence of the lobules. Immunohistochemical studies showed a normal pattern of distribution for keratin-positive thymic epithelial cells against a background rich in CD3/TdT/CD1a+ lymphocytes. Twenty-nine cases had an initial clinical or pathological diagnosis of thymoma or thymoma vs thymic hyperplasia. Clinical follow-up in 26 cases showed that all patients were alive and well between 5 and 15 years after diagnosis (mean, 9 years). Thymic parenchymal hyperplasia causing significant enlargement of the normal thymus that is sufficient to cause symptoms or worrisome imaging findings should be considered in the differential diagnosis of anterior mediastinal masses. The criteria for distinguishing such lesions from lymphocyte-rich thymoma are presented.

Inclusion of thymic Langerhans cell histiocytosis in the "5 Ts" of the differential diagnosis of anterior mediastinal mass.

Inclusion of thymic Langerhans cell histiocytosis in the "5 Ts" of the differential diagnosis of anterior mediastinal mass.

Utility of percutaneous ultrasound guided biopsy in the diagnosis of anterior mediastinal mass lesions

Introduction: mediastinal masses include a broad spectrum of histopathological and radiological entities. Although imaging modalities aid at narrowing the purposed differential diagnosis, accurate categorization is not always possible. Objective: to assess the efficacy as well as safety of percutaneous ultrasound guided biopsy modality in the proper diagnosis of anterior mediastinal lesions.Materials and methods: Forty patients presented with anterior mediastinal masses were enrolled in this study. Each patient was subjected to CT chest with contrast, US guided biopsy from the anterior mediastinal lesions and obtained specimens underwent histopathological examination. Then, patients were observed for possible post-procedural complications. Results: 97.5% of the included cases were symptomatic; with dyspnea [representing 62.5%] was the most frequent complaint among our cases, followed by cough and fever representing 50% and 37%, respectively. The most frequent lesions were lymphoma (40%) followed by metastatic carcinoma (25%) and thymoma (15%). Two cases showed inconclusive results (failure rate 5%).Conclusions: Combined clinico-radiological data can narrow the differential diagnosis of anterior mediastinal masses; yet histopathological examination remains the mainstay of the precise diagnosis. Percutaneous US guided biopsy is claimed to be a useful, minimally invasive cost-effective tool for proper sampling, with minimal complications and low failure rate.

Differential Diagnosis of Anterior Mediastinal Masses in Children (Literature Review with Their Own Clinical Observations)

The article is devoted to the description of the X-ray anatomy of the mediastinum, the evolution of the classification of this anatomical region. As well as systematization of radiological signs of the most common formations of the anterior (prevascular) mediastinum in children. Based on these data, a table of the most characteristic radiographic features of various neoplasms of different groups. Reflected basic criteria differential diagnosis of various tumors of the anterior mediastinum.

A SHEEP IN WOLF'S CLOTHING: BENIGN TERATOMA MASQUERADING AS MALIGNANT THYMOMA

TOPIC: Disorders of the Mediastinum TYPE: Medical Student/Resident Case Reports INTRODUCTION: Metastatic parietal pleural implants can be seen in patients with thymoma. Benign teratomas are not associated with parietal pleural implants. We describe resection of a benign teratoma, appearing as a locally advanced thymoma with parietal pleural implants. CASE PRESENTATION: A 37-year-old healthy female was found to have an incidental large pericardial mass on screening breast MRI. A CT Chest showed a 9.4 cm well-defined hypoattenuating calcified cystic lesion with mass effect on the right atrium (Figure 1). Her preliminary diagnosis was thymoma. In the operating room, thoracoscopy demonstrated a large mass with involvement of the pulmonary parenchyma, pericardium, parietal pleural implants, and visceral pleural implants. (Figure 2A, B, C). Robotic en bloc resection was performed. The mass was mobilized with the resection of portions of the upper and middle lobes, pericardium and away from the remaining thoracic structures including the phrenic nerves (Figure 2C, D). Intra-operative frozen section of the mass revealed benign teratoma. Frozen section of the parietal pleural implants revealed fibrosis with teratomatous elements on final pathology (Figure 3). A single chest drain was placed. The patient did well postoperatively and was discharged on postoperative day four. DISCUSSION: To our knowledge, this is the first report of a benign mature teratoma masquerading as a metastatic thymoma. Approximately half of all mediastinal masses in adults are in the anterior mediastinum. The most common mediastinal tumor in adults is thymoma. Thymoma, although considered a low-grade neoplasm, has a propensity for locally invasiveness and recurrence. For these reasons, all thymomas should be approached as aggressive(1). In contrast, benign mature teratomas are well-circumscribed and indolent. Although there is potential for malignant transformation, complete resection results in cure(2). The current recommendation for diagnosis of anterior mediastinal mass is up front resection unless neoadjuvant or medical therapy is being pursued as treatment(1). Preoperative imaging, while helpful, cannot reliably delineate between thymoma and teratoma(3). The higher incidence of thymoma in adults makes the preoperative diagnosis of thymoma more likely. CONCLUSIONS: This case highlights the importance of performing an R0 resection given the known aggressiveness of thymomas as well as highlighting that things are not always as they seem. REFERENCE #1: Detterbeck FC ed. Pathology of the Mediastinum. New York: Cambridge University Press, 2014 REFERENCE #2: Lewis BD, Hurt RD, Payne WS et al Benign Teratomas of the Mediastinum J Thorac Cardiovasc Surg 1983; 86 (5): 727-731. REFERENCE #3: Tomiyana N, Honda O, Tsubamoto M et al Anterior Mediastinal Tumors: Diagnostic Accuracy of CT and MRI. Eur J Radiol. 2009; 69 (2): 280-288. DISCLOSURES: No relevant relationships by Mia DeBarros, source=Web Response No relevant relationships by Grant Fischer, source=Web Response No relevant relationships by M. Blair Marshall, source=Web Response No relevant relationships by Sue Wang, source=Web Response

Anesthetic management during anterior mediastinal mass resection in a pediatric patient. A case report

Complications induced by general anesthesia (GA) and neuromuscular relaxation (NMR) in anterior mediastinal mass (AMM) resection can be serious, especially when there are signs of compression of the airway or large vessels (dyspnea, orthopnea, etc.) (1). It is preferable to perform the procedure in spontaneous ventilation to avoid respiratory or cardiovascular collapse due to the supine position or to loss of negative intrathoracic pressure with GA and NMR. If the supine position and NMR are unavoidable, procedures should be performed in a step-wise manner, and rescue strategies should be prepared (rescue position, bronchoscope, sternotomy). Correct preoperative evaluation, adequate planning, and a multidisciplinary approach will ensure patient safety. We present the case of a child with a history of severe orthopnea and a diagnosis of AMM and lymphoblastic lymphoma (respiratory arrest and cardiovascular collapse during sedation for lumbar puncture and bone marrow biopsy) that did not respond to medical treatment and required resection surgery under GA with NMR.

Intra-thymic bronchogenic cyst an extremely rare tumor of anterior mediastinum in adults

BackgroundIntra-thymic bronchogenic cysts are a rare entity but should be considered in the differential of all non-invasive thymic masses.Case presentationWe describe a 50-year-old patient who was found to have an incidental thymic mass on computer tomography of the chest. Non-invasive thymoma was suspected and a thoracoscopic thymectomy was performed. Final pathology revealed a bronchogenic cyst.ConclusionIntra-thymic bronchogenic cysts are extremely rare tumors of the anterior mediastinum. It should be considered in differential diagnosis of anterior mediastinal masses.

Anterior mediastinal masses — A multidisciplinary pathway for safe diagnostic procedures

ObjectiveThe objective of this study was to report our multidisciplinary diagnostic approach for patients with anterior mediastinal masses (AMM). MethodsA retrospective review of patients with AMM at a tertiary pediatric surgical oncology centre (January 2011–December 2016) was performed. We analyzed data on clinical presentation, mode of tissue diagnosis, anesthetic techniques, and complications. ResultsOf the 44 patients admitted with AMM (median age 11 years, 27 males and 17 females), 22 had respiratory symptoms. Imaging revealed tracheobronchial compression in 26 children. Twenty patients had a lymph node biopsy. Ten patients had image-guided core biopsy of the mediastinal mass, and 2 had mediastinoscopic biopsy of a paratracheal lymph node. One patient with likely recurrence of a relapsed metastatic ethmoid carcinoma did not have a biopsy. The diagnosis was made from alternative tissues, such as pleural fluid in 4 and peripheral blood in 7 patients. Twenty-five anesthetics were assessed, as 14 patients required no or only local anesthesia, and 5 had unavailable anesthetic notes. Eighteen of 25 patients were anesthetized maintaining spontaneous breathing, mostly by means of ketamine sedation. There were no major anesthetic complications. ConclusionSafe tissue diagnosis of anterior mediastinal masses can be obtained by a personalized multidisciplinary approach. Use of alternative tissues, local anesthesia, and ketamine sedation help minimize the need for general anesthesia, muscle paralysis, and controlled ventilation. Level of evidenceIV (Case Series with no Comparison Group).

Positron emission tomography/computed tomography as a clinical diagnostic tool for anterior mediastinal tumors.

The purpose of this study was to assess the usefulness of positron emission tomography/computed tomography (PET/CT) in the differential diagnosis of anterior mediastinal tumors. A total of 94 patients with anterior mediastinal masses or nodules (male, n = 41; female, n = 53; age, 17-84years) were retrospectively evaluated. All patients were evaluated by PET/CT and the masses or nodules were histologically diagnosed in our institution. Anterior mediastinal masses and nodules were classified into two disease categories: Low (thymic hyperplasia, thymoma, mature teratoma, and MALT lymphoma) and High (thymic carcinoid, thymic cancer, diffuse large B-cell lymphoma, T-cell lymphoblastic lymphoma, Hodgkin's lymphoma, and malignant germ cell tumors) groups. The sensitivity and specificity of maximum standardized uptake value (SUVmax) 7.5 for the detection of High group were 77% and 100%, respectively. The SUVmax distributions of the WHO histological thymoma types and Masaoka stage thymomas extensively overlapped. Masaoka stage III thymomas had significantly higher SUVmax than Masaoka stage I thymomas. Regarding the TNM classification, the SUVmax of T3 and T1b thymomas was higher than T1a thymoma. Although the SUVmax of each disease overlapped, PET/CT findings provided useful information for the differential diagnosis of anterior mediastinal masses.

Is It Time for a Nonionizing Radiation Technique for Biopsy of Anterior Mediastinal Masses?

AJR 2016; 206:W95 0361–803X/16/2066–W95 © American Roentgen Ray Society Is It Time for a Nonionizing Radiation Technique for Biopsy of Anterior Mediastinal Masses? We read with interest the recent article by Petranovic et al. [1] that examined the diagnostic accuracy and safety of CT-guided percutaneous biopsy of anterior mediastinal masses (AMMs). The authors showed that this technique is feasible, accurate, and safe and has a high overall diagnostic yield of 77%. We are extremely convinced that rapid and correct diagnosis of AMMs is the key process in therapeutic decision making and that an adequate histologic specimen is fundamental for determining the correct choice of treatment. Most AMMs are nonsurgical tumors, such as lymphoma, whereas surgical tumors, such as thymomas, are rare. Therefore, a noninvasive diagnostic technique that provides adequate histologic specimens, allows rapid diagnosis, and avoids the need for unhelpful and more invasive procedures is welcome. Garnon et al. [2] recently published a study in which they evaluated the diagnostic yield and accuracy associated with the use of MRI-guided percutaneous biopsy for AMMs. Their study and the study by Petranovic et al. [1] both show that the MRI-guided approach and the CT-guided technique are feasible, accurate, and safe. What about associated cost and exposure to ionizing radiation? In our clinical practice, we recently introduced an ultrasound-guided minimally invasive diagnostic technique for performing percutaneous biopsy of AMMs with the use of a single-size full-core end-cut needle. This technique appears to be safe, is quite easy to use, may avoid the need for the use of a more invasive diagnostic procedure, and eliminate ionizing radiation exposure for patients and operators. Our initial data appear to be comparable with the data on the more invasive and more expensive ionizing diagnostic techniques reported in previous articles. In our limited experience, use of this ultrasound-guided minimally invasive diagnostic technique when performing percutaneous biopsy of AMMs drastically reduced the number of mediastinoscopies, videothoracoscopies, and anterior mediastinotomies performed, and the technique may offer a valid and safe alternative to CT-guided biopsy that does not involve ionizing radiation. Bartolomeo Lorenzati Azienda Ospedaliera Universitaria Citta della Salute e della Scienza Cuneo, Italy Riccardo Cristofori Elio Rolfo, Citta della Salute e delle Scienze, Torino, Italy

Mediastinal germ cell tumors.

Mediastinal germ cell tumors are among the most common tumors in the anterior mediastinum. This tumor should be considered strongly in the differential diagnosis of anterior mediastinal masses. Benign teratomas are common in this site, and complete surgical resection results in cure of nearly all patients. Malignant mediastinal seminomas are highly curable and either radiotherapy (mediastinal disease) or cisplatin-based chemotherapy (metastatic disease) will result in long-term survival in 80% or more of patients. Mediastinal nonseminomatous germ cell malignancies represent a clinically and biologically distinct subset of mediastinal germ cell neoplasms. Relative to their testicular counterparts, these tumors carry a poor prognosis, but, with newer refinements in cisplatin-based chemotherapy, approximately half of these patients will survive their illness. The history of success with chemotherapy should prompt thorough pathologic and serologic evaluation of all patients with mediastinal malignancies in hopes of defining a curable process. In particular, poorly differentiated carcinomas at this site should be treated as germ cell tumors, and so long-term survival will be attainable. Mediastinal nonseminomatous germ cell tumors are associated with the development of nongerm cell malignancies such as embryonal rhabdomyosarcomas and hematologic malignancies such as acute megakaryocytic leukemia and malignant histiocytosis. The development of these associated malignancies is not related to therapy and represents a true biological link between these malignancies. It is likely that the development of these malignancies is an expression of the multipotential nature of primitive germ cells. Careful clinical and biologic investigations of these rare transformations may lead to greater understanding of the regulation of events in the malignant process.

HYPERPLASIA OF THYMIC GLAND: LEFT VIDEO-ASSISTED THORACOSCOPIC APPROACH

Hyperplasia of thymic gland is a rare benign entity that should be considered in the differential diagnosis of anterior mediastinal masses in children and young adolescents. We report a case of a patient with a thymic mass, diagnosed occasionally for respiratory symptoms and treated by video-assisted thoracoscopic surgery. A previously healthy 10 years-old boy presented to our hospital for retrosternal pain and dyspnea with restriction to daily activities from four months. Diagnostic imaging was performed, including a chest x-ray and a magnetic resonance imaging, showing a large homogeneous antero-superior mediastinal mass, more extended on the left side. The additional laboratory analysis, considered essential for differential diagnosis with myasthenia gravis and lymphoma, resulted negative. In view of these findings, our patient underwent to video assisted thoracoscopy with left-sided approach for a total resection of thymus and perithymic fat. The patient made an excellent recovery without postoperative complications and was discharged from the hospital four days later. Histopathological examination showed a normal thymic architecture like a true thymic hyperplasia. At follow up, chest x-ray was normal in absence of pleural and parenchimal alterations. Thoracoscopic thymectomy is a safe technique that allows to achieve the goal of early thymectomy with the advantages of less invasive procedure.

Ectopic mediastinal goiter successfully managed via cervical approach: Case report and review of the literature

Ectopic mediastinal goiter is a rare entity that presents diagnostic and treatment challenges to the clinician. A case of primary ectopic mediastinal goiter is presented and use of a cervical approach for excision is described herein. Additionally, precedent literature highlighting surgical treatment approaches is reviewed. The distinction between primary and secondary ectopic mediastinal goiter is significant as this indicates the vascular supply to the ectopic mass. Previous authors suggested open thoracic procedures for all primary mediastinal goiters to safely divide intrathoracic vascular supply, but favorably positioned anterior mediastinal goiter may be safely removed via cervical approach. This is the second case of primary ectopic mediastinal goiter successfully resected via cervical approach. Select cases of primary mediastinal goiter may be amenable to excision via cervical approach, avoiding potential complications of open thoracic procedures. Additionally, CT-guided biopsy is an effective tool in preoperative diagnosis of anterior mediastinal masses.

Extralobar Sequestration in Anterior Mediastinum With Pericardial Agenesis

We report a very rare case of extralobar sequestration and pericardial agenesis in a 22-year-old man. A computed tomographic (CT) scan demonstrated an anterior mediastinal mass. No aberrant artery was preoperatively identified. The patient underwent surgery with an impression of thymoma. An extralobar sequestration receiving its blood supply from the left pulmonary artery, accompanied with pericardial agenesis, was noted at the time of operation. The anterior mediastinum is an unusual site for extralobar sequestions. It is recommended to include extralobar sequestration in the differential diagnosis of anterior mediastinal masses, even if the aberrant artery is not recognized on the computed tomographic scan.

Primary Hodgkin's disease of the thymus

The thymus is a lymphoid organ located in the antero-superior mediastinum and composed of heterogeneous admixture of lymphoid and epithelial elements. Thymic tumors are dominated by thymoma; lymhomas are uncommon involving the gland secondary to adenopathies. Primary thymic lymphomas are exceptional. We report a 25-year-old man referred to us because of chest pain and irritating cough since 2 months. Physical examination was normal and no lymph nodes were palpable. Chest radiography showed an anterior mediastinal mass. Computed tomography (CT) examination of the chest revealed a homogeneous tissular mass occupying the anterior mediastinum in its upper and medium stage, extending to the infundibulum without lymph node enlargement. Thymectomy and wedge were performed via a median sternotomy. Pathologic diagnosis was nodular sclerosis Hodgkin's disease of the thymus. The patient received 6 cycles of ABVD (Adriamycin [doxorubicin], bleomycin, vinblastin and dacarbazine) and mediastinal radiotherapy. Currently, tow years after diagnosis, he is well and free of disease. Primary thymic Hodgkin's lymphoma is a rare entity which should be included in the differential diagnosis of anterior mediastinal mass especially in young patients.

Minimally invasive approaches for histological diagnosis of anterior mediastinal masses

Anterior mediastinal masses include a wide variety of diseases from benign lesions to extremely malignant tumors. Management strategies are highly diverse and depend strongly on the histological diagnosis as well as the extent of the disease. We reported a prospective study comparing the usefulness of core needle biopsy and mini-mediastinotomy under local anesthesia for histological diagnosis in anterior mediastinal masses. A total of 40 patients with masses of unknown histology and located either at or near the anterior mediastinum received biopsy prior to treatment. The diagnostic methods were core needle biopsy in 28 patients and biopsy through mini-mediastinotomy under local anesthesia in 15 patients (including 3 patients for whom core needle biopsy failed to yield a definite diagnosis). Histological diagnosis was achieved in 18 of the 28 patients receiving core needle biopsy. Of them, all 4 patients with pleural fibromas and 9 of the 12 patients (75%) with pulmonary mass were diagnosed definitively. In the remaining 12 patients with mediastinal mass, histological diagnosis was achieved in only 5 patients (41.7%). In contrast, biopsy through a mini-mediastinotomy failed in only 3 patients. In the remaining 12 patients with huge mediastinal masses, who underwent mini-mediastinotomy, a definitive histological diagnosis was reached by pathological and/or immunohistochemical study (diagnostic yield 85.7% in 12 of 14 cases of mediastinal mass, P = 0.038 vs core needle biopsy). For the 9 patients with thymic epithelial tumors, the diagnostic yield was 40% (2 in 5 cases) for core needle biopsy and 83.3% (5 in 6 cases) for mini-mediastinotomy. There was no morbidity in patients receiving mini-mediastinotomy. In the 30 patients with biopsy-proven histological diagnosis, the results contributed to therapeutic decision making in 25 cases (83.3%). Core needle biopsy is effective in the diagnosis of pulmonary and pleural diseases. Yet its diagnostic yield in mediastinal mass is rather low. Superior to core needle biopsy, biopsy through a mini-mediastinotomy under local anesthesia is highly effective in the histological diagnosis of anterior mediastinal mass, and has a satisfactory diagnostic yield. The method is safe, minimally invasive, cost-effective, and useful in therapeutic decision making for anterior mediastinal masses.

Extended cervical mediastinoscopy in the diagnosis of anterior mediastinal masses

Background. Although transthoracic needle biopsy (TNB) has been the preferred method for the diagnosis of anterior mediastinal masses, it has inherent limitations in accuracy. In particular, lymphoma and thymoma are diagnosed less reliably using needle biopsy. Videothoracoscopy has been advocated as an alternative method for diagnosis. Our goal was to assess the usefulness of extended cervical mediastinoscopy (ECM) in the diagnosis of anterior mediastinal masses. Methods. The ECM technique was performed in 9 patients in whom TNB and Tru-cut biopsies had been inefficient for histologic diagnosis. All lesions were in the anterior mediastinum. Extended cervical mediastinoscopy was carried out using the same incision as in a standard cervical mediastinoscopy and dissection was performed behind the sternum as previously published. Mean operative time was 50 minutes (range 40 to 70 minutes) and mean hospital stay was 8 hours (range 5 to 36 hours). Results. Diagnosis of lymphoma in 4 cases, thymoma in 3 cases, and thymic hyperplasia in 2 cases were obtained by ECM. In 1 of 2 patients with suspected thymoma who underwent resectional surgical procedures, final histologic diagnosis was non–small cell lung carcinoma. There was no surgical mortality or intraoperative complication. One patient had minimal pneumothorax requiring no intervention. Conclusions. We conclude that ECM in the diagnosis of anterior mediastinal masses is technically feasible and provides an alternative to the conventional approaches in patients with paraaortic or aortopulmonary masses.

Mediastinal Germ Cell Tumors

Mediastinal germ cell tumors are a rare malignant process, but one of the most common tumors found in the anterior mediastinum. Mediastinal seminoma has the same radiosensitivity as the testes primary. Localized mediastinal seminoma may be successfully treated with radiotherapy alone, with excellent cure rates. Patients with bulky tumors will often have residual radiographic abnormalities. Retrospective studies have provided evidence that close observation without surgical intervention may be a viable option. Patients with extra-mediastinal spread require systemic cisplatin-based chemotherapy. In contrast, all patients with nonseminomatous mediastinal germ cell tumors require systemic chemotherapy with cisplatin-based chemotherapy as the initial approach. These patients require resection of any persistent postchemotherapy radiographic abnormalities. Mediastinal germ cell tumors are also associated with a variety of unusual clinical conditions. The first recognized association was the increased incidence of mediastinal germ cell tumors with Klinefelter's syndrome. As experience with the histopathology of mediastinal germ cell tumors increased, several unusual variants were recognized, such as embryonal rhabdosarcoma, small cell undifferentiated carcinoma, adenocarcinoma, and neuroblastoma. Lastly, a unique association with mediastinal germ cell tumors and acute megakaryocytic leukemia was noted that was not related to prior chemotherapy. In summary, mediastinal germ cell tumors are numerically rare, but one of the most common tumors in the anterior mediastinum with unique biologic and clinical properties. This tumor should be considered strongly in the differential diagnosis of anterior mediastinal masses.

General Anesthesia Prior to Treatment of Anterior Mediastinal Masses in Pediatric Cancer Patients

Many children with malignant diseases who present with an anterior mediastinal mass must undergo general anesthesia for tissue diagnosis or tumor resection. One hundred sixty-three pediatric patients over a period of 6 yr were admitted to Memorial Sloan-Kettering Cancer Center with a diagnosis of anterior mediastinal mass. Forty four of these patients required surgery and their records were reviewed. In recent years perioperative radiation therapy has been advocated for this patient group prior to their receiving general anesthesia. If a tissue diagnosis has not been made, preoperative radiation therapy may distort histologic findings and prevent accurate diagnosis. All patients with an anterior mediastinal mass who must receive general anesthesia in our institution do so prior to treatment with radiation or chemotherapy even in the presence of cardiovascular or respiratory symptoms. No patient died or sustained permanent injury as a result of their anesthetic or operative experience. Two patients who experienced difficulty on induction of anesthesia required tracheal intubation with a rigid bronchoscope. Two patients developed airway obstruction during anesthetic maintenance that was corrected with changes in patient position. Four patients were unable to have their tracheas extubated at the conclusion of surgery and one patient required tracheal reintubation in the immediate postoperative period. These patients were treated with radiation therapy and chemotherapy after tissue for diagnosis had been obtained. The authors conclude that in the absence of life-threatening preoperative airway obstruction and severe clinical symptoms general anesthesia may be safely induced prior to radiation therapy.

True thymic hyperplasia: A clinicopathological study

In this report, we describe the clinicopathological features of 4 patients with true thymic hyperplasia. This controversial thymic lesion has only recently been defined as a variable, often massive enlargement of the thymus characterized by a nearly normal microscopic structure. Our study of 4 patients and review of the literature indicate that true thymic hyperplasia has a well-defined clinicopathological profile: prevalence in children or young male patients, absence of associated autoimmune diseases, and often presence of respiratory distress or peripheral blood lymphocytosis, or both. True thymic hyperplasia should be considered in the differential diagnosis of anterior mediastinal masses in children and young adolescents.