Best cases from the AFIP: thymoma

Thymic masses and mimics in adults: review of common and uncommon pathologies

The thymus is a primary lymphoid organ that plays a key role in the immune system development. Normally, it is located in the anterior mediastinum and it changes tissue composition with progressive fatty involution with age. The spectrum of pathological processes involving the thymus include enlargement, tumour development, and cystic change. In addition, other local pathology can mimic thymic disease. Differentiating these entities can be challenging; however, recognizing key features on imaging is essential to appropriately guide further investigation and therapy. The focus of this pictorial review will be to highlight the important distinguishing features of thymic hyperplasia, thymomas, thymic cysts, thymic neuroendocrine tumours (NETs), thymolipomas, mediastinal teratomas, and other mimics of thymic disease. Knowledge of the varying imaging findings on computed tomography and magnetic resonance imaging is valuable for radiologists to appropriately classify disease, avoid misdiagnosis, and expedite therapy.

CHEST PAIN DUE TO A GIANT THYMOMA IN AN ADOLESCENT BOY

Chest pain in children is a common referral for emergency examination, although it is believed that the underlying condition is not a serious event. The authors present the case of a 17 years old male with complaints of chest pain with a very recent onset, constant, experienced after physical effort. All medical history and physical examination findings were normal, the poster-anterior chest X-ray revealed a heterogenous opacity in the middle third of the right hemithorax confirmed on computerized tomography as a large solid anterior mediastinal mass with a diameter of 7.5/10.3 cm. By thorax surgery the mass was identified in the anterior and superior mediastinum and total resection was achieved for the tumor mass and thymus. Pathology examination showed poor small and medium epithelial cells proliferation and the tumor was classified as thymoma type 1B. Mediastinum is a rare location of space occupying processes in children. Also, there is a high rate of asymptomatic lesions in this area, considering that half of them are incidentally discovered for various chest X ray examinations. Many causes of chest pain in children are benign; nonetheless, some serious events do exist sometimes and pediatricians must pay attention to identify and manage those cases.

Pictorial essay of radiological features of benign intrathoracic masses

With increased exposure of patients to routine imaging, incidental benign intrathoracic masses are frequently recognized. Most have classical imaging features, which are pathognomonic for their benignity. The aim of this pictorial review is to educate the reader of radiological features of several types of intrathoracic masses. The masses are categorized based on their location/origin and are grouped into parenchymal, pleural, mediastinal, or bronchial. Thoracic wall masses that invade the thorax such as neurofibromas and lipomas are included as they may mimic intrathoracic masses. All examples are illustrated and include pulmonary hamartoma, pleural fibroma, sarcoidosis, bronchial carcinoid, and bronchoceles together with a variety of mediastinal cysts on plain radiographs, computed tomography (CT) and magnetic resonance imaging (MRI). Sometimes a multimodality approach would be needed to confirm the diagnosis in atypical cases. The study would include the incorporation of radionuclide studies and relevant discussion in a multidisciplinary setting.

Pediatric thymoma with a difference: report of a case and review of literature

Thymoma represents <1% of all mediastinal tumors in children. Less than 50 cases of pediatric thymoma are reported in the literature. Thymomas are considered to be highly aggressive in pediatric patients, especially when age is <10 years. Paraneoplastic syndromes, of which around 70% are myasthenia gravis, correlate with poor prognosis. In this article, we report a case of a thymoma in an 8-year-old boy, who had favorable histopathology (Masaoka stage I, WHO type B2), despite the presence of young age and necrosis along with absence of myasthenia gravis. We have also reviewed the available literature on pediatric thymoma.

Incidental detection of a benign thymoma on Tc-99m MIBI myocardial perfusion study

Technetium-99m methoxy-isobutylisonitrile (Tc-99m MIBI) is a routinely used radiopharmaceutical for myocardial perfusion scintigraphy (MPS). It is also a tumor seeking agent. Here, we present a case of 51 year old male who underwent Tc-99m MIBI myocardial perfusion study due to permanent chest pain after coronary angiography. Abnormal MIBI uptake in the thorax was detected in the raw images. This single finding led to further investigation and thoracotomy proved that the lesion was benign thymoma. Thymomas are often asymptomatic or have a non-specific presentation. They are often detected coincidentally on images performed for any other reasons. We wanted to emphasize that during of MPS, the raw data should always be reviewed as occasionally valuable additional information on noncardiac pathology could be recognized by extracardiac uptake, as in this case.

Conflict of interest:None declared.

Detection of an occult thymoma on99Tcm-Tetrofosmin myocardial scintigraphy

Thymoma is an uncommon tumour, which is often asymptomatic and may be detected coincidentally on cross-sectional imaging performed for other reasons. We report a case of thymoma detected on myocardial scintigraphy performed for suspected coronary artery disease. Extracardiac pathology may be suggested by abnormal non-cardiac tracer uptake on myocardial scintigraphy. An awareness of the potential causes of this is essential to allow potentially life threatening non-cardiac disorders to be recognized and treated promptly.

Imaging of thymic disorders

Evaluation of the thymus poses a challenge to the radiologist. In addition to age-related changes in thymic size, shape, and tissue composition, there is considerable variability in the normal adult thymic appearance within any age group. Many different types of disorders may affect the thymus, including hyperplasia, cysts, and benign and malignant neoplasms, both primary and secondary; clinical and imaging findings typical for each disease process are described in this article. Whereas computed tomography is the mainstay for imaging the thymus, other imaging modalities may occasionally provide additional structural or functional information.

Thymoma in a child: case report and review of the literature

Thymic lesions comprise approximately 2-3% of all pediatric mediastinal tumors and include thymic cysts, hyperplasia, carcinoma, and thymomas. Thymomas, which represent less than 1% of all mediastinal tumors, are rare mediastinal tumors in the pediatric population. Fewer than 30 cases in children have been described in the literature. These tumors are typically aggressive, with poor outcomes. We report a thymoma in a 14-year-old girl and review the available literature on thymomas and their treatment.

Imaging findings of expansile lesions of the thymus

The purpose of this article is to review the imaging findings of the different expansile lesions of the thymus. Almost 50% of all mediastinal masses are located in the anterior mediastinum. The thymus is the most common site of origin of these masses. Several kinds of lesions can arise from this gland because it derives from the three embryonic germ cell layers. Primary neoplasms of the thymus are thymoma, thymolipomas, carcinoma, carcinoid, primary germ cell tumors, and lymphoma. The latter can also involve the organ in a secondary fashion. Other lesions that cause thymic enlargement and that can be confused with neoplasia are thymic cysts and thymic hyperplasia. Even though anterior mediastinal masses are first found on conventional radiographs, computed tomography and magnetic resonance are very useful additional studies for assessing the origin and extension of these masses. The basic concepts regarding embryology, anatomy, and histology relevant for the differential diagnosis of an enlarged thymic gland are also described.

Imaging Evaluation of Pediatric Mediastinal Masses

Mediastinal masses in children are a heterogeneous group of asymptomatic to potentially life-threatening congenital, infectious, or neoplastic lesions that can present complex diagnostic and therapeutic dilemmas. This article presents the imaging features of the common mediastinal masses seen in the pediatric population. Classification of the masses is performed according to the traditional mediastinal compartment model, consisting of the anterior, middle, and posterior mediastinum. This scheme facilitates differentiation of the variety of disorders.

Spectrum of Thymic Uptake at18F-FDG PET

Fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) has emerged as a strong diagnostic tool for the diagnosis and staging of neoplasms. Uptake in the thymus at (18)F-FDG PET complicates the assessment of mediastinal involvement by tumor in children and young adults. Increased thymic (18)F-FDG uptake may represent normal physiologic uptake but may also indicate the presence of thymic hyperplasia, lymphomatous infiltration, primary thymic neoplasm, or metastatic disease. Familiarity with the patterns of (18)F-FDG uptake that characterize these pathologic conditions is crucial to the interpretation of PET findings in the thymus. In addition, awareness of the subsets of patients in whom physiologic uptake may be seen and of the normal morphologic features and (18)F-FDG PET appearance of the thymus, along with a general sense of the upper limits of metabolic activity for physiologic thymic uptake, will aid in differentiating between physiologic thymic uptake and mediastinal disease. In equivocal cases, correlation with morphologic data from computed tomography or magnetic resonance imaging will likely continue to play a key role in diagnosis and will aid in differentiating benign thymic uptake from malignancy.

Imaging of the mediastinum: applications for thoracic surgery

The diagnostic approach to patients who have mediastinal masses should include thorough preoperative imaging. Once limited to plain radiographic techniques, the radiologist now has a wide variety of imaging modalities to aid in the evaluation of the mediastinum. CT is the imaging modality of choice for evaluating a suspected mediastinal mass or a widened mediastinum, and it provides the most useful information for the diagnosis, treatment, and evaluation of postoperative complications.