Immunohistochemistry in the diagnosis of thymic epithelial. Thymic hyperplasia surgical pathology criteria stanford. Thymic rebound hyperplasia radiology reference article. Pathology thymus hyperplasia can be subdivided into two forms. The difference between the mean suvmax for thymic hyperplasia, thymoma and thymic carcinoma was statistically significant. Enlarging mediastinum on petct after treatment for hodgkin s. Additionally, we found out correct and erroneous cases of each imaging in detecting thymic lesions. Thymic hyperplasia consists of two subtypes, true hyperplasia and lymphoid hyperobjective. Thymic rebound hyperplasia is considered a from of true thymic hyperplasia pathology. They are usually asymptomatic and mostly occur in the anterior mediastinum. Comparison between ct and mri in the diagnostic accuracy of. Printable thymic hyperplasia surgical pathology criteria. There are two types of thymic hyperplasia, lymphoid follicular hyperplasia and true hyperplasia. This website is intended for pathologists and laboratory personnel, who understand that medical information is imperfect and must be interpreted.
Thymic uptake can challenge the accurate assessment of cancer patients by 18ffdg imaging. Of the primary thymic malignancies, neuroendocrine tumors nets are the least common, accounting for 2 to 5 percent of thymic tumors. Differentiation of rebound and lymphoid thymic hyperplasia. Both true thymic hyperplasia and lymphoid hyperplasia manifest as. Rebound reactive thymic hyperplasia after chemotherapy. We performed the statistical analysis with the software statistical package for the. Here are some questions you can ask your cancer care team to help you better understand your diagnosis and. The thymus may contain cysts, usually less than 4 cm in diameter. T cells are critical to the adaptive immune system, where the body adapts specifically to. On the opposedphase image, hyperplasia presents a signal intensity decrease, whereas the. Inaoka and colleagues used chemical shift mr imaging to differentiate thymic hyperplasia including patients with rebound hyperplasia and hyperplasia associated with graves disease from thymic neoplasms including thymoma, thymic carcinoma and lymphoma based on the premise that this technique allows identification of normal fat infiltration. In periods of bodily stress the thymus may acutely shrink to 40% of its original volume depending on the severity and duration of the stress. Dualenergy ct perfusion imaging for differentiating who. The embryonic derivation of the thymus is the 3rd pharyngeal pouch.
The difference between the suvmax of high risk and low risk thymoma was. Imaging characteristics of thymic hyperplasia statistical analysis differences in imaging characteristics between the groups with true hyperplasia and lymphoid hyperplasia were compared using fisher. Analyses were performed by using the stata 11 software package stata. Clinical features, diagnosis and thoracoscopic surgical. Correlation with world health organization classification and clinical staging. Imaging findings or procedure details thymic hyperplasia. The socalled lymphofollicular hyperplasia, which is caused by the occurrence of hyperplastic lymph follicles within the organ, is constantly associated with autoimmune diseases e. It is not intended to be and should not be interpreted as medical. The purpose of this article is to investigate the imaging characteristics of pathologically proven thymic hyperplasia and to identify features that can differentiate true hyperplasia from lymphoid hyperplasia. Thymic cysts are a rare, benign anomaly and represent % of all mediastinal masses. Magnetic resonance imaging mri is not routinely used to detect. It is characterized by generalized hyperplasia with preserva.
Laboratory of molecular imaging and therapy, cancer research institute, seoul national university, seoul, korea. The diagnosis of thymic epithelial neoplasms is normally. Jeter background what is the embryonic derivation of the thymus. It is not intended to be and should not be interpreted as medical advice or a diagnosis of any health or fitness problem, condition or disease. Benign thymic hyperplasia, or thymic rebound, should be included in the differential diagnosis of a soft tissue mass appearing in the anterior mediastinum on followup imaging. Immunohistochemistry in the diagnosis of thymic epithelial neoplasms annikka weissferdt, md, frcpath and cesar a. A thymic hyperplasia case without suppressing on chemical. Graves patient with thymic expression of thyrotropin receptors. Thymic hyperplasia as defined in the literature, refers only to thymic lymphoid hyperplasia. Thymic hyperplasia is frequently observed in graves disease. Update in diagnostic imaging of the thymus and anterior. Thymic lymphoid hyperplasia with multilocular thymic cysts.
A generic term for an increase in size and weight of the thymus, which may be true hyperplasia e. During the recovery phase it can grow back to its original size or even larger up to 50% larger. Research paper comparison between ct and mri in the. In lymphoid hyperplasia the medulla show increased lymphoid follicles while the cortex atrophies. Statistical analysis statistical analyses were performed with spss 23. To prospectively evaluate chemical shift magnetic resonance mr imaging for differentiating thymic hyperplasia from tumors of the thymus gland. To evaluate the role of conventional contrastenhanced ct cect imaging and dualenergy spectral ct dect perfusion imaging in differentiating the who histological subtypes of. Both true thymic hyperplasia and lymphoid hyperplasia manifest as diffuse symmetric enlargement of the thymus so that it is difficult to distinguish between the two types on the basis of imaging findings alone. Thymic hyperplasia is an entity that results in enlargement of the thymus, often to the. In some cases, however, the morphological heterogeneity.
The thymus is a specialized primary lymphoid organ of the immune system. In and outofphase fast gradientecho imaging is a rapid t1weighted sequence that has been shown to be useful in distinguishing normal thymus and thymic hyperplasia from thymic neoplasms and lymphoma and can serve as the t1weighted unenhanced sequence for this examination. Inaoka and colleagues used chemical shift mr imaging to differentiate thymic hyperplasia including patients with rebound hyperplasia and hyperplasia associated with graves disease from thymic. About 15% of patients with myasthenia gravis have follicular thymic hyperplasia and about 50% of patients with follicular thymic hyperplasia have myasthenia. Physiologic thymic uptake of ffdg in children and young. This case first appeared as performance improvement program in surgical pathology. Accurate imaging of the thymus is essential in the diagnosis and surgical treatment of both neoplastic and nonneoplastic conditions. Distinguishing hyperplastic thymus from tumors was better with sii than csr. The term is potentially vague and the more precise terminology below should be used. The difference between the suvmax of high risk and low risk thymoma was not significant. Thymus hyperplasia can be subdivided into two forms. Enlarging mediastinum on petct after treatment for.
He reported two thymic hyperplasia cases without fat that was not detected on chemical shift imaging but was found on diffusionweighted mri due to the high adc values 1. Differential diagnosis of thymic tumors using a combination of 11cmethionine pet and fdg pet. True thymic hyperplasia is usually regarded as a rebound phenomenon and. The content on this site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. Thymic cysts can occur along the neck or in the chest mediastinum. After a cancer diagnosis, staging provides important information about the amount of cancer in the body and expected response to treatment. Thymic hypoplasia definition of thymic hypoplasia by. Thymus cancer early detection, diagnosis, and staging. Routine chest ct and mri can effectively identify thymoma, but neither is reliable to differentiate between thymic hyperplasia and normal thymus.
Rebound reactive thymic hyperplasia after chemotherapy in. Imaging of the thymus is a rather complex task, which affects both. This form of thymic hyperplasia is encountered in 65% of patients with myasthenia. The thymus is in the ant mediastinum mn, involved in the processing.
The effect of diagnostic imaging on surgical treatment. Characterization of thymic masses using 18ffdg petct. Thymic hyperplasia is a disorder whereby there is hyperplasia of the thymus gland. The diagnosis of thymic epithelial neoplasms is normally rendered after careful evaluation of their histologic features. Thymic cysts are usually detected incidentally and do not generally cause symptoms. Roc receiver operating characteristics analysis was applied to compare the.
The maximal thymic lobar thickness for triangular thymuses in adults aged 2030 years is 1. Chemicalshift magnetic resonance mr imaging has proved extremely useful for the characterization of lesions and organs with fatty components. Magnetic resonance imaging mri is useful both for initial diagnosis of a mediastinal mass and for followup evaluation after treatment. Mar 26, 2020 to evaluate the role of conventional contrastenhanced ct cect imaging and dualenergy spectral ct dect perfusion imaging in differentiating the who histological subtypes of thymic epithelial. The size of the thymus usually peaks during adolescence, and atrophies in the following decades. Imaging of thymic epithelial neoplasms sciencedirect. Imaging characteristics of pathologically proven thymic. Mri can help differentiate between a possible mediastinal mass and a vascular abnormality such as an aortic aneurysm. Cysts usually just contain fluid and are lined by either many layers of flat cells or columnshaped cells. Thymic lymphoid hyperplasia is often present with myasthenia gravis as well as other autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis. In periods of bodily stress the thymus may acutely shrink to 40% of its original volume depending on the severity.
Diffusionweighted mr imaging in thymic epithelial tumors. Thymic uptake can challenge the accurate assessment of cancer. Lymphoid follicular hyperplasia, also known as autoimmune thymitis. Mr imaging, sii and csr have high accuracy to distinguish thymic. True thymic hyperplasia is a rebound phenomenon characterized by an increase in mass of the thymus, both in size and weight, in response to a stressor such as steroid treatment, chemotherapy, irradiation. The diagnosis of hyperplasia included all thymus tissues with thymic. Thymic rebound hyperplasia is considered a from of true thymic hyperplasia. Where is the thymus located, and what is its function.
Therefore, distinguishing thymic hyperplasia from thymic tumors is difficult. Routine chest ct and mri can effectively identify thymoma, but neither is reliable to differentiate between thymic hyperplasia and normal thymus in patients with myasthenia gravis. Ct is currently considered the crosssectional imaging technique of choice in the identification, staging, and followup of patients with tets. Physiologic thymic uptake of 18ffdg in children and young. Thymic hyperplasia definition of thymic hyperplasia by. Differentiation of rebound and lymphoid thymic hyperplasia from. The current study of imaging features of pathologically confirmed cases of thymic hyperplasia found that ct attenuation of lymphoid hyperplasia was significantly higher than that of true hyperplasia, with the optimal threshold of greater than 41. Zhengzhou city science and technology innovation talents training program. A thymic primary site accounts for approximately 0. A total of 32 patients with spaceoccupying mediastinal masses were enrolled and early and delayed phase images were collected. May 10, 2008 benign thymic hyperplasia, or thymic rebound, should be included in the differential diagnosis of a soft tissue mass appearing in the anterior mediastinum on followup imaging, particularly. About 15% of patients with myasthenia gravis have follicular thymic hyperplasia and about 50% of patients with follicular thymic hyperplasia have myasthenia other associated disorders include. Correlation between thymus radiology and myasthenia. Page 3 of 19 thymic hyperplasia is subdivided into two.