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Thymic Cyst

A thymic cyst is an epithelium lined cyst involving the thymus. These cysts are often separated into congenital or acquired types. Congenital cysts are thin-walled, having thymic tissue in their lining and acquired cysts are multilocular and are usually formed as a result of an inflammatory process.


Most mediastinal cysts, including thymic cysts, are asymptomatic and incidentally found after chest imaging for other reasons. Approximately half of individuals with thymomas and thymic cysts are clinically asymptomatic. Symptoms are more commonly observed in infants and children, in which the cyst enlarges and compresses structures producing related symptoms [1]. For example, a thymic cyst may enlarge to compress the trachea resulting in dyspnea. Adults may present with non-specific chest pain, cough, stridor, and/or dyspnea [2].

Chest Discomfort
  • The patient had complained of coughing and chest discomfort for several years. A chest X-ray film revealed the shadow of a large abnormal mass in the anterior mediastinum. We diagnosed it as a thymic cyst.[ncbi.nlm.nih.gov]
  • A 35-year-old, HIV-infected male intravenous drug abuser, who complained of worsening central chest discomfort and pain on deep inspiration, was found to have a large, septated anterior mediastinal mass.[ncbi.nlm.nih.gov]
  • Some patients however may present with symptoms of dyspnea or chest discomfort. On computed tomography scan, the lesions are usually multilocular and sharply demarcated from mediastinal fat and soft tissue.[jemds.com]


Workup consists of ensuring the proper diagnosis of a thymic cyst and ruling out associated benign and malignant conditions such as: cystic teratoma, lymphangioma, cystic degeneration of a seminoma, pericardial cyst, thymoma, and thymic cancer [3]. Workup begins with patient history, physical exam, and imaging tests. The most common imaging modality currently used to evaluate a mediastinal mass is a chest computed tomography (CT) scan. Other imaging modalities used include magnetic resonance imaging and integrated positron emission tomography and CT (PET/CT) scan. A definitive diagnosis is established by pathological tissue examination (via biopsy or surgical resection).

On standard chest radiographs, thymic cysts may not be visible or may be indistinguishable from other non-lobulated thymic masses [4]. Further workup should include a chest computed tomography (CT) scan and biopsy if clinically indicated. On CT scan, congenital thymic cysts usually appear as well-defined water-attenuated masses with translucent walls. Multilobular thymic cysts appear as well-defined, heterogeneous, cystic masses with a visible wall [5] [6]. Some thymic cysts, in particular acquired cysts, may have an increased CT attenuation if infection or hemorrhage is present; these cysts may be erroneously diagnosed as solid masses. In some cases, there may be curvilinear calcification of the cyst wall [7].

Magnetic resonance imaging (MRI) depicts thymic cysts having typical characteristics of fluid (e.g., low signal intensity on T1-weighted images and uniform high signal intensity on T2-weighted images). If hemorrhage or infection is present, the cysts will show high signal intensity on both T1- and T2-weighted images. In summary, uncomplicated thymic cysts have the following characteristics on MRI [8]:

  • T1-weighted images - low signal
  • T2-weighted images - high signal
  • T1 C+ (Gd) images: no intrinsic enhancement
  • If hemorrhage or infection occurs, then there will be high signal intensity on both T1 and T2-weighted images.

A PET/CT scan provides a CT image as well as information about the avidity of the lesion for glucose (FDG uptake). Malignant cells tend to have higher glucose avidity, hence producing a high uptake value on the PET/CT scan. This information can provide clues about whether a thymic lesion is a benign cyst or malignant entity [9].

Definitive diagnosis is achieved by obtaining tissue for pathologic examination by way of either a surgical biopsy or surgical resection. Most surgical resections are performed using minimally invasive surgical technique called video-assisted thoracoscopy (VATS). VATS biopsy requires the patient to be placed under general anesthesia in the operating room. More recently, robotic surgical approach has been used to evaluate and resect mediastinal masses (including thymic cysts) [10].

Right Pleural Effusion
  • Clinical and laboratory examinations indicated a right pleural effusion. Then, the patient was transferred to the 2nd Department of Propedeutic Surgery of 'LAIKO' Hospital where he underwent surgery.[ncbi.nlm.nih.gov]
Multilocular Cyst
  • Histologic evaluation confirmed a multilocular cyst lined mainly by mucinous epithelium with focal areas of ciliated and squamous lining.[ncbi.nlm.nih.gov]
  • In addition to lymphoid hyperplasia similar to that associated with human immunodeficiency virus infection in lymph nodes and other sites, the thymus was characterized by multilocular cysts with squamous epithelial lining (multilocular cystic lesion of[ncbi.nlm.nih.gov]
  • Multilocular cysts have been reported in association with a variety of neoplastic, autoimmune, and infectious conditions.[ncbi.nlm.nih.gov]
  • To the best of our knowledge, this is the first report of aspiration cytology of a mediastinal seminoma associated with a multilocular cyst.[ncbi.nlm.nih.gov]
  • cysts: May have more layers of squamoid, cuboidal, columnar, micropapillary or mixed glandular epithelium May have pseudoepitheliomatous hyperplasia Usually cholesterol granulomas Commonly lymphocytes, granulation tissue, hemorrhage Cysts separated by[pathologyoutlines.com]


  • The etiologic theories, differential diagnosis and the treatment of thymic cysts are discussed.[ncbi.nlm.nih.gov]
  • Because of the possible coexistence of typical congenital thymic cyst and thymoma, we recommend surgical resection both for establishing the diagnosis and for definite treatment.[ncbi.nlm.nih.gov]
  • Treatment consisted of dual-chamber pacemaker implantation prior to video-assisted removal of the thymic cyst.[ncbi.nlm.nih.gov]
  • This therapy may be one of the best treatments for thymic cysts, especially in very elderly patients.[ncbi.nlm.nih.gov]
  • We report the successful diagnosis and treatment of a 76 year-old female with a giant, benign thymic cyst.[ncbi.nlm.nih.gov]


  • Surgery is the treatment of choice and prognosis is excellent if the lesion is completely removed.[revistas.rcaap.pt]
  • Thymic cysts are benign and prognosis is excellent once excised. Total surgical removal is recommended [7] .[ejcts.oxfordjournals.org]
  • Prognosis Prognosis after resection of a mediastinal tumor varies widely depending on the type of lesion resected. After resection of mediastinal cysts and benign tumors, prognosis is generally excellent.[emedicine.medscape.com]
  • The results and prognosis of surgical treatment for primary mediastinal tumors in children. J Jpn Assoc Chest Surg 1995;9:135. Saito Y, Uragami T, Satake A, Yamakawa Y, Kasugai T. [Multilocular thymic cyst].[jpmsonline.com]
  • McCusker M, Basset-Seguin N, Dummer R, Lewis K, Schadendorf D, et al. (2014) Metastatic basal cell carcinoma: prognosis dependent on anatomic site and spread of disease. Eur J Cancer50:774-783.[omicsonline.org]


  • Delay in recognizing the underlying etiology can lead to significant complications.[ncbi.nlm.nih.gov]
  • The etiologic theories, differential diagnosis and the treatment of thymic cysts are discussed.[ncbi.nlm.nih.gov]
  • […] abundant epithelioid granulomata within the cyst, a finding that has not previously been emphasized as a histologic feature of these lesions, and one that expands the histopathologic differential diagnosis, warranting exclusion of infectious and autoimmune etiologies[ncbi.nlm.nih.gov]
  • Inflammation in Thymic Cysts is idiopathic, although in some cases a specific etiology (HIV infection, Autoimmune Disorder) is to be ruled out.[jemds.com]
  • Etiology Thymus cyst etiology (A) the cause of the disease At present, the thymus cyst is congenital, because the thymus cysts are found in the thymus development line, such as the neck and mediastinum, thymus cysts accounted for about 1% of mediastinal[healthfrom.com]


  • […] pouch, as is parathyroid gland Usually presents as incidental mass in anterosuperior mediastinum Congenital (unilocular) or acquired (multilocular) Rarely occur postoperatively Mixed multilocular thymic cyst: has parathyroid or salivary gland tissue Epidemiology[pathologyoutlines.com]
  • Epidemiology A review of collected series reveals that many mediastinal neoplasms and masses vary in incidence and presentation depending on patient age.[emedicine.medscape.com]
Sex distribution
Age distribution


  • Pathophysiology Tumors and cysts of the mediastinum can produce abnormal effects at both systemic and local levels.[emedicine.medscape.com]


  • Thymic cyst can be diagnosed only by histopathology and the knowledge of this entity will prevent its misdiagnosis. Keywords: Cervical, child, thymic cyst How to cite this article: Jindal A, Sukheeja D.[jscisociety.com]
  • Prevention Thymus cyst prevention As the disease is congenital disease, the key to prevention is early detection and early treatment.[healthfrom.com]
  • In conclusion, when treating MTCs, complete surgical resection should be performed to prevent recurrence. Careful pathological examinations are also essential to exclude coexisting malignancy. 4.[file.scirp.org]
  • Grossly, they had a spongy appearance with typical microscopy. [19] Surgical intervention is the preferred line of management of all mediastinal cysts, regardless of size and clinical presentation, so as to prevent development of various complications[jpgmonline.com]



  1. Hamaji M, Ali SO, Burt BM. A meta-analysis of surgical versus nonsurgical management of recurrent thymoma. Ann Thorac Surg. 2014; 98:748-55.
  2. Rieger R, Schrenk P, Woisetschlager R, Wayand W. Videothoracoscopy for the management of mediastinal mass lesions. Surg Endosc. 1996;10:715-7.
  3. Suster S1, Rosai J. Multilocular thymic cyst: an acquired reactive process. Study of 18 cases. Am J Surg Pathol. 1991;15:388-98.
  4. Jeung MY, Gasser B, Gangi A, et al. Imaging of cystic masses of the mediastinum. Radiographics: a review publication of the Radiological Society of North America, Inc. 2002; 22:S79-93.
  5. Choi YW, McAdams HP, Jeon SC, et al. Idiopathic multilocular thymic cyst: CT features with clinical and histopathologic correlation. Am J Roentgenol 2001; 177:881-885.
  6. Brown LR, Aughenbaugh GL. Masses of the anterior mediastinum: CT and MRI findings. AJR Am J Roentgenol 1991; 157:1171-80.
  7. Strollo DC, Rosado-de-Christenson ML, Jett JR. Primary mediastinal tumors. Part 1. Tumors of the anterior mediastinum. Chest 1997; 112:511-22.
  8. Zhang M, Endo M, Adachi S, et-al. Multilocular thymic cyst: MR findings. AJR Am J Roentgenol. 1994;163:479-80.
  9. McErlean A, Huang J, Zabor EC, Moskowitz CS, Ginsberg MS. Distinguishing benign thymic lesions from early-stage thymic malignancies on computed tomography. Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer. 2013; 8: 967-73.
  10. Rieger R, Schrenk P, Woisetschlager R, Wayand W. Videothoracoscopy for the management of mediastinal mass lesions. Surg Endosc. 1996;10:715-7.

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Last updated: 2017-08-09 17:38