Benign Thymic Cyst Research Articles

P129 RARE CASE OF A GIANT THYMIC CYST: A CHALLENGING DIFFERENTIAL DIAGNOSIS OF A PARACARDIAC CYSTIC LESION

Abstract Background Benign thymic cysts are a rare clinical entity, representing approximately 3% of all mediastinal masses and can be congenital or acquired. We report a case of a 58–year–old female with a giant benign thymic cyst which entered in differential diagnosis with pericardial cyst and pericardial effusion. Case presentation: A 58–year–old female was brought to our hospital due to new onset dyspnoea and fatigue. She had a history of a mediastinal liquid mass incidentally discovered 9 years before which was interpreted at that time as a loculated pericardial effusion (Fig. 1). An echocardiogram was performed and it revealed increased size of the known lesion without any signs of hemodynamic compromise (Fig. 2). A magnetic resonance showed a voluminous liquid lesion that originated from the anterior mediastinum, extending caudally to the diaphragm with maximum dimension on the right hemithorax of 16 x 12 x 9 cm and on the left hemithorax of 10 x 5 x 13 cm (antero–posteriorly, transversely and cranio–caudally respectively) (Fig. 3). It was initially interpreted as a pericardial cyst. All the findings were then collegially reviewed and it was suspected of being a giant thymic cyst especially due to its rapid growth and spatial evolution over time. The cyst was surgically removed using a thoracoscopic approach. Histological examination confirmed the thymic origin of the cyst and excluded malignancy. At three month follow up, the patient presented no symptoms, and the echocardiogram was normal. Discussion The echocardiographic features of mediastinal cysts are not specific for the type of cystic lesion, so the origin and location of the cyst can be used for differential diagnosis. Computed tomography has the best spatial resolution, while the magnetic resonance has better capacity to differentiate the content of the cyst, especially when it is not a homogeneous liquid lesion. In our case, the growth over nine years was a crucial hint to suspect the thymic origin of the lesion. On the other hand, the sole evaluation of the last imaging exam would have made the diagnosis more challenging because of its huge dimensions, which made the exact site of origin almost impossible to identify. Conclusion Our case is a rare example of a giant thymic cyst which was extremely difficult to differentiate from other paracardiac cystic lesions and required integrated imaging and discussion by a team of experts of different specialties to make the correct diagnosis.

186 RARE CASE OF A GIANT THYMIC CYST: A CHALLENGING DIFFERENTIAL DIAGNOSIS OF A PARACARDIAC CYSTIC LESION

Abstract Background Benign thymic cysts are a rare clinical entity, representing approximately 3% of all mediastinal masses. Thymic cysts can be congenital or acquired. We describe a case of a 58-year-old female with a giant benign thymic cyst which entered in differential diagnosis with a pericardial cyst and pericardial effusion. Case presentation A 58-year-old female was brought to our hospital due to new onset dyspnoea and fatigue. She had a history of a liquid mediastinal mass accidentally discovered 9 years before which was interpreted at that time as a loculated pericardial effusion (Fig. 1). An echocardiogram was performed which showed increased size of the known lesion without any signs of hemodynamic compromise (Fig. 2). A magnetic resonance showed a voluminous liquid lesion that originated from the anterior mediastinum, extending caudally to the diaphragm with maximum dimensions on the right hemithorax of 16×12×9 cm (antero-posteriorly, transversely and cranio-caudally respectively) and of 10×5×13 cm on the left hemithorax (Fig. 3). It was initially interpreted as a pericardial cyst. All the findings were then collegially reviewed and for the first time it was suspected of being a giant thymic cyst, especially due to its spatial distibution and growth over time; in particular the cranio-caudal growth in both the hemithoraxes suggested that it might have originated from the thymus gland and then, by force of gravity, extended downword bilaterally. The cyst was surgically removed using a unilateral thoracoscopic approach. Histological examination confirmed the thymic origin of the cyst and excluded malignancy. At the three month follow up, the patient presented no symptoms, and the echocardiogram was normal. Discussion The echocardiographic features of mediastinal cysts are not lesion-specific, so the origin and location of the cyst can be used for differential diagnosis. Computed tomography has the best spatial resolution, while the magnetic resonance has better capacity to differentiate the content of the cyst, especially when it is not a homogeneous liquid lesion. In our case, spatial distribution and, in particular, growth over nine years were crucial hints to suspect the thymic origin of the lesion. Indeed, the sole evaluation of the last imaging exam would have made the diagnosis more problematic because of its huge dimensions, which made the exact site of origin very challenging to identify. Conclusion Our case is a rare example of a giant thymic cyst which was extremely difficult to differentiate from other paracardiac cystic lesions and required integrated imaging and discussion by a team of experts of different specialties to make the correct diagnosis.

Glutamic Acid Decarboxylase Antibody in a Patient with Myelitis: A Retrospective Study

Objective: The aim of this study was to evaluate the positive rate of serum glutamic acid decarboxylase (GAD) autoantibody in patients with myelitis and to describe the clinical findings in patients with positive GAD antibody. Methods: Serum samples were collected from 390 patients with myelitis, including 210 patients positive for aquaporin 4 (AQP4) antibody and 180 patients negative for AQP4. GAD65 antibody was measured by an indirect immunofluorescence assay. Results: Only 1 serum and cerebral spinal fluid sample from 390 patients (0.26%) was positive for anti-GAD antibodies. The patient was a female with relapsing myelitis and a thymic mass. Thymic resection was undertaken, and pathological examination revealed a benign thymic cyst. Extensive infiltration of lymphocytes positive for CD3, CD4, CD8 and CD20 was found. Immunohistochemistry showed positive expression of GAD65 in the cyst. Conclusions: Although serum GAD65 antibodies were present in a patient, it is not recommended to routinely screen for GAD65 antibodies in patients with myelitis because of their rare occurrence. However, screening for GAD65 antibodies should be considered in patients who have been diagnosed with cancer or a thymic abnormality.

Abstract #1073 A Mystic Cystic Mass: A Case of a Benign Thymic Cyst in a Patient with Papillary Thyroid Cancer

Abstract #1073 A Mystic Cystic Mass: A Case of a Benign Thymic Cyst in a Patient with Papillary Thyroid Cancer

Solide Raumforderung im vorderen Mediastinum

Summary A solid tumour in the anterior mediastinum A 71-year-old asthmatic presented with increasing shortness of breath, which was attributed to an acute asthma exacerbation and responded rapidly and completely to appropriate treatment. Chest x-ray revealed a left parahilar mass which was new compared to a film taken 2 years previously. Subsequent CT scan of the chest showed the mass to be a tumour measuring 7.8 x 5.6 cm, situated in the anterior mediastinum between the aortic arch and the pulmonary artery. Its density was reported to be that of a solid mass (mean density –2 Hounsfield units). Transthoracic ultrasound revealed the surprise finding of a cystic lesion, and transthoracic fine needle aspiration revealed clear acellular liquid. The lesion was removed surgically and histopathology established the diagnosis of a benign thymic cyst. Such cysts are rare; computed tomography may be misleading as a diagnostic tool, whereas ultrasound is more accurate in documenting the cystic nature of the process. Surgical excision is the treatment of choice to preclude malignant transformation. It also serves to avoid secondary complications due to compression of surrounding structures by further cystic growth.

Complete recovery of an isolated left vocal fold palsy associated with a benign mediastinal thymic cyst

To present a case of benign mediastinal thymic cyst, and to review the published information on these cysts, including their incidence, presentation, diagnosis and management. We report the case of a 55-year-old man who presented with a unilateral vocal fold palsy subsequently found to be due to the presence of a benign mediastinal thymic cyst. A literature search was undertaken to identify the incidence, key features and management of this rare condition. Benign mediastinal thymic cysts are a rare cause of mediastinal masses. Usually diagnosed incidentally, their management is usually surgical. Vocal fold palsy in isolation has not previously been reported in association with mediastinal thymic cysts. This report describes what we believe to be the first published case of a completely reversible vocal fold palsy presenting in association with a rare benign mediastinal thymic cyst.

Thoracoscopic resection of bulky intrathoracic benign lesions

Video-assisted thoracic surgery (VATS) is used for the diagnosis and treatment of some mediastinal lesions. However, large-size tumours are usually approached by thoracotomy or sternotomy. We report our experience of a full thoracoscopic approach for bulky intrathoracic lesions. From November 2002 to March 2007, 14 patients with a bulky intrathoracic mass were referred for resection. The study group consisted of eight females and six males with a mean age of 44 years (range: 13-74). We defined as bulky a mass with a minimal cross-sectional diameter equal to or larger than 50 mm, as measured on the specimen by the pathologist. Thoracoscopic resection was completed in all patients. In 4 cases, the mass originated from the pleura, and in 10 cases from the mediastinum. The larger diameter of the lesion ranged from 50 mm to 160 mm, with a median of 90.2 mm. Operative time, calculated from insertion of the first trocar to skin closure, ranged from 40 to 190 min (mean: 102). Mean chest drain duration was 2.1 days (range: 1-4 days) and the mean hospital stay was 4.3 days (range: 3-11 days). There were no major postoperative complications. The final pathological diagnoses were the following: solitary fibrous tumours of the pleura (4), benign thymic cysts (2), teratomas (2), bronchogenic cyst (1), benign thymoma (1), pleuropericardial cyst (1) and benign neurogenic tumours (3). With experience and use of appropriate instrumentation, resection of bulky intrathoracic lesions by thoracoscopy is feasible and safe. It should be considered as a reliable alternate for tumours that are benign and most often asymptomatic.

Thymic carcinoma in a child with HIV infection

HIV infection predisposes to cancer during childhood. In addition to the AIDS-defining non-Hodgkin lymphoma (NHL) and Kaposi sarcoma, a range of other lymphoid malignancies and solid tumors have been described. We report the first case of an HIV-positive child with thymic carcinoma in the setting of regressing thymic cysts. The tumor expressed CKIT but failed to respond to imatinab mesylate after a transient response to multiagent chemotherapy. This case extends the spectrum of pediatric malignancy in the setting of HIV and suggests that patients with presumed benign thymic cysts require ongoing surveillance.

Application of Robotic-Assisted Techniques to the Surgical Evaluation and Treatment of the Anterior Mediastinum

We report our initial experience with the application of robotic-assisted technologies to the treatment of diseases of the anterior mediastinum. Between October 2001 and December 2003, 18 consecutive patients with anterior mediastinal masses were referred for diagnosis and treatment. Fifteen patients underwent robotic-assisted surgery with the da Vinci robotic system. A single surgical team performed all operations. Resection was accomplished by either median sternotomy or robotic-assisted techniques. Fourteen patients underwent successful robotic-assisted thymectomy. One patient underwent robotic-assisted biopsy of a mass that was later determined to be a poorly differentiated carcinoma, 3 patients underwent complete thymectomy by median sternotomy for biopsy-proven extracapsular thymoma, 7 patients had thymoma, and 3 had myasthenia gravis. There were 2 patients each with benign thymic cysts and thymic hyperplasia. Primary thymic carcinoid, thymolipoma, papillary thyroid cancer, and poorly differentiated carcinoma were present in 1 patient each. No conversions, intraoperative complications, or deaths occurred in the 15 patients who underwent robotic-assisted resection. The mean operative time was 96 minutes (range 62 to 132 minutes). The mean robotic time was 48 minutes (range 22 to 76). The median hospital stay was 2 days. All patients are doing well, with a median follow-up of 1 year. Robotic-assisted surgery of the anterior mediastinum, and particularly thymectomy, can be performed safely and efficiently. The increased visualization and instrument dexterity afforded by this technology provides an optimal minimally invasive approach to the anterior mediastinum. From this experience we have formulated a comprehensive treatment algorithm for the surgical evaluation and treatment of patients with anterior mediastinal diseases.

Cervical thymic cyst

Neck is a common site for the appearance of cystic masses. Although cervical thymic cyst is a rare lesion it should be included in the differential diagnosis. Because of the rarity of “clinically significant” remanants of thymus in neck, the two cases of benign cervical thymic cyst have been discussed in the present article.

Thymic cyst appearing after treatment of mediastinal non‐Hodgkin lymphoma

We report the first case of a thymic cyst appearing in the course of treatment for non-Hodgkin lymphoma of the anterior mediastinum. The patient was a 9-year-old child in whom an abnormal contour of the left cardiac border persisted after chemotherapy, suggesting residual disease. The mass was found at thoracotomy to be a benign thymic cyst. The lesion was not present 2 years previously, and most likely represented cystic degeneration of the thymus, secondary to lymphomatous involvement. CT scan was not helpful in distinguishing the cystic lesion from residual lymphoma.

Thoracoscopy in the management of anterior mediastinal masses

Thoracoscopy has been found useful for both the diagnosis and treatment of anterior mediastinal disorders. We have reserved it for use during thymectomy in the management of new-onset myasthenia gravis and for the resection of benign thymic, pericardial, and bronchogenic cysts. The application of thoracoscopic techniques in the anterior mediastinum should be approached conservatively. At this time, we believe it should be limited to diagnostic procedures requiring adequate biopsy and to therapeutic resections in which the extent of the resection is assured and therapeutic efficacy is maintained. We await further advances in both the instrumentation and technique before we are willing to undertake the performance of more radical resections using thoracoscopy. The efficacy of thoracoscopic thymectomy in the setting of myasthenia gravis awaits confirmation by larger clinical trials with adequate follow-up.

Multilocular thymic cysts with pseudoepitheliomatous hyperplasia

Six cases are described of benign thymic cysts of the anterior mediastinum showing focal pseudoepitheliomatous hyperplasia of the lining epithelium. The patients' ages ranged from 11 to 54 years; five cysts occurred in males and one in a female. Histologically, the lesions were characterized by exuberant proliferation of the cyst lining epithelium that grew as sheets and tongues of atypical squamous cells with large, hyperchromatic nuclei, prominent nucleoli, and scattered mitotic figures. The walls of the cyst adjacent to the areas of epithelial proliferation showed abundant hemorrhage, necrosis, and severe inflammatory changes. All cases were treated by local surgical excision. There was no evidence of recurrence or metastases over a follow-up period of up to 8 years (average follow-up, 4 years). It is proposed that pseudoepitheliomatous hyperplasia may develop in thymic cysts as an expression of regeneration of the lining epithelium in response to the inflammatory, hemorrhagic, and necrotizing changes which often accompany these lesions. This should not be mistaken for malignancy, and should be distinguished from the exceptional cases of true thymic neoplasms seen in association with thymic cysts.

Cases of the day. General. Benign thymic cyst complicated by hemorrhage.

Cases of the day. General. Benign thymic cyst complicated by hemorrhage.

Computed tomography and magnetic resonance imaging diagnosis of thymic cyst

A case of mediastinal thymic cyst evaluated by computed tomography and magnetic resonance imaging is presented. The anterior mediastinal mass was well-demarcated and measured 10 Hounsfield units on the computed tomographic scan. The lesion showed intermediate signal intensity on T1-weighting and became hyperintense on T2-weighted images. These computed tomography and magnetic resonance imaging features suggested a cystic structure, which proved to be a benign thymic cyst on pathologic examination.

Case report: Benign thymic cyst following mantle radiotherapy for Hodgkin's disease

The case history of a patient who was treated for Stage IA Hodgkin's disease involving the left supraclavicular region is presented. Shortly after mantle field radiation therapy she developed a mass in the anterior mediastinum. Histological examination of the lesion revealed it to be a benign cyst of the thymus. We consider it important that the possibility of the existence of such a benign growth be considered when a mediastinal mass appears in a patient treated for Hodgkin's disease, before more intensive tumour therapy is given.

Cystic lesion of the thymus: An occasionally malignant cervical and/or anterior mediastinal mass

Between 1965 and 1982, we treated 46 patients with cystic lesions of the thymus. Thirty patients had anterior mediastinal cysts, nine had cysts which were large enough to be both cervical and mediastinal, and seven had cervical cysts. The majority (40/46) presented with asymptomatic masses. Six patients presented with distinct complaints: dysphagia (four patients), hoarseness owing to vocal cord paralysis (one patient), and cervical pain (one patient). All six had benign thymic cysts. The diagnosis of a cystic mass was established prior to operation by ultrasonography and computed axial tomography in our last three patients. These two techniques delineated the capsule and the central fluid in those three cases. All 46 patients had the mass resected without mortality or significant morbidity, except for resection of the phrenic nerve in one patient with malignant cystic thymoma. Cervical cysts were excised through cervical incisions. Cysts located in the anterior mediastinum and cervical-mediastinal cysts required median sternotomy or right thoracotomy for successful resection. Pathological examination showed that 39 patients had benign thymic cysts, three had benign cystic thymoma, two had malignant thymoma, one had a seminoma arising in the thymus, and one had a lymphoblastoma. We believe that a cystic thymic mass which can be detected by ultrasonography and computed tomography, although usually benign, does not eliminate the possibility of malignancy, and resection, therefore, is indicated.

Computed tomography of the abnormal thymus.

Computed tomography (CT) should be the imaging method of choice following plain chest radiographs when a suspected thymic abnormality requires further evaluation. Based upon a six-year experience, including the evaluation of 25 patients with thymic pathology, CT was found useful in suggesting or excluding a diagnosis of thymoma and in distinguishing thymic hyperplasia from thymoma in patients with myasthenia gravis. The thickness of the thymic lobes determined by CT was found to be a more accurate indicator of infiltrative disease (thymic hyperplasia and lymphoma) than the width. CT was helpful in differentiating benign thymic cysts from solid tumors, and in defining the extent of a thymic neoplasm. On occasion, CT may suggest the specific histologic nature of a thymic lesion.

Surgical treatment of thymic cysts and neoplasms in children

Based on experience with 17 patients and review of the literature, complete excision is possible for all benign thymic cysts and neoplasms. Recurrence is rare (2%). Most malignant thymomas in children are epithelial (73%). As with adults, prognosis depends on accurate surgical staging and aggressive surgical intervention. Even the largest tumors can be completely excised removing portions of lung, pleura, diaphragm, and pericardium in continuity as required. Cardiopulmonary bypass may be necessary when the innominate veins or the superior vena cava is involved. Irradiation is required for stage II and stage III lesions. Stage IV patients require irradiation and chemotherapy.

Mediastinal Thymic Cyst after Open Heart Surgery

A benign thymic cyst seen six years after valvular heart surgery is described, and the question of the possible role of previous surgical trauma in the development of the cyst is raised.