Medical Image of the Month: Thymolipoma

Figure 1. Chest radiograph PA view revealing subtle prominence of left upper heart border (white arrow).

Figure 2. CT Topogram: The prominence of left heart border is discretely seen suggesting pliability of the lesion (due to supine position).

Figure 3. CECT axial and coronal images revealing a fat containing anterior mediastinal mass with strands of soft tissues (HU values as depicted in image).

Figure 4. CECT of the thorax one year after resection: post contrast image revealing no mediastinal mass lesion.

A 20-year-old man presented with a continuous, mild, dull aching pain affecting the left chest pain for 15 days duration. There were no aggravating or relieving factors nor any history of fever, respiratory or cardiac symptoms. The patient’s vital signs were normal and examination of the respiratory and the cardiovascular systems revealed no abnormality. Electrocardiography and biochemical investigations, including cardiac enzymes, were normal. Chest radiography (Figure 1) revealed a subtle opacity causing fullness of the aorto-pulmonary window with subtle, smooth prominence of the left upper cardiac border; the left hilum was visualised discretely through the opacity (Figure 2). The patient underwent enhanced contrast chest CT (CECT, Figure 3) for further evaluation, revealing a large mass measuring 13 x 7.9 x 5 cm in the anterior mediastinum, extending from thoracic inlet to the left cardiophrenic angle. The mass consisted predominantly of fat density, with an average attenuation of - 84 Hounsfield units (HU). Non-enhancing strands of soft tissue foci (mean, 32 HU) were also seen within the lesion. No areas of calcification or cystic degeneration were present. Planes between the subjacent mediastinal structures were preserved (Figures 2 and 3). A radiological impression of thymolipoma was offered. The patient was transferred to a tertiary care center where he underwent thoracoscopic excision and histopathology confirmed thymolipoma. Following surgery, the patient recovered uneventfully and follow up chest radiography and enhanced contrast chest CT (Figure 4) showed no evidence of lesion recurrence.

Thymolipoma is a rare benign tumor originating in the anterior mediastinum, and comprises 2-9% of all thymic neoplasms (1). Cytogenetic analyses have demonstrated that thymolipoma is a neoplasm of thymic fat (2). There is no sex or age predilection and affected patients range in age from 3-76 years. Most patients remain asymptomatic until the size of the lesion produced local mass effects, resulting in symptoms such as cough, dyspnea, hemoptysis, chest pain and hoarseness (1,3). Autoimmune diseases, including myasthenia gravis, systemic lupus erythematosus, hypogammaglobulinemia, Graves’ disease, and erythroblastopenia, may coexist in 10% patients (1).

When thymolipomas are small, the lesion may not be detectable at chest radiography. When the lesion grows larger, it classically usually “drapes” around the heart and may simulate cardiomegaly (4). Extremely large thymolipomas have been described and can mimic pericardial effusion, pericardial cysts or pericardial tumors (5). Ultrasound can be used to differentiate fluid-containing lesions, such as pericardial effusion and cysts, from the echogenic fat typical of thymolipoma (4). Excessive epicardial fat, diaphragmatic elevation, sequestration or lobar collapse may also mimic this condition at chest radiography, whereas CT and/or MRI are diagnostic, revealing circumscribed anterior mediastinal fatty mass containing islands and strands of soft tissues with no invasion of adjacent structures (3-5).

Important differential diagnostic considerations for thymolipoma at cross sectional imaging include other fat-containing mediastinal masses such as mediastinal lipoma, mediastinal lipomatosis, liposarcoma and lipoblastoma. Lipomas are encapsulated whereas liopmatosis is an unencapsulated deposition of adipose tissues, and both lesions typically show homogeneous fat attenuation with no soft tissue strands. Liposarcoma frequently occurs in the posterior mediastinum and is usually symptomatic at the time of presentation, and often manifests with inhomogeneous appearance and invasion of subjacent mediastinal structures on CT/ or MRI (6). Lipoblastoma usually occurs under the age of 3, and shows intratumoral soft tissue stranding. Thymomas do not contain fatty tissue whereas some germ cell neoplasms contain cystic areas and calcification in addition to the fatty tissue (3,6). CT is considered the modality of choice for the evaluation of mediastinal masses in general, and thymolipoma in particular. For patients in whom CT findings are equivocal, or for patients with contraindications to enhanced CT (such as contrast media allergy) MRI may be utilized for further characterization of mediastinal lesions, such as thymolipoma. Encasement or invasion of the mediastinal vasculature, esophagus, and trachea as well as involvement of the pericardium, myocardium, and pleura are accurately detected with MRI. The primary disadvantages of using MRI for mediastinal lesion characterization include limited identification of calcifications, longer imaging time, and higher cost (3,6). Since thymolipomas are benign, and typically well encapsulated, with no invasion of surrounding structures, if detected incidentally, the lesion can be followed with imaging. However, when symptoms related to local mass effect develop, surgical resection is the treatment of choice which can be performed using a minimally invasive approach, such as thoracoscopic excision, with open resection reserved for larger lesions (7). Histopathological examination of thymolipoma reveals mature adipose tissue and hyperplastic thymic structures with Hassall’s corpuscles (2).

Amit Kumar Paliwal MD¹, Dr. Pradeep Jaiswal MCH (CTVS) AH

(R&R)², and Dr. Vivek Sharma MD³

¹Military Hospital Dehradun, Dehradun, Uttrakhand, India      

²Delhi Cantt, Delhi, India

³Command Hospital (CC), Lucknow, India

References

1. Dongel I, Imamoglu H, Şahin AF, Yıldırım S, Bayram M. A rare mediastinal tumor: thymolipoma. Eur J Gen Med. 2014;11:21-3. [CrossRef]
2. Hudacko R, Aviv H, Langenfeld J, Fyfe B. Thymolipoma: Clues to pathogenesis revealed by cytogenetics. Ann Diagn Pathol. 2009;13:185-8.[CrossRef] [PubMed]
3. Tomiyama N, Honda O, Tsubamoto M et al. Anterior mediastinal tumors: diagnostic accuracy of CT and MRI. Eur J Radiol. 2009;69(2):280-8. [CrossRef] [PubMed]
4. Yeh HC, Gordon A, Kirschner PA, Cohen BA. Computed tomography and sonography of thymolipoma. AJR Am J Roentgenol. 1983;140(6):1131-3. [CrossRef] [PubMed]
5. Gamanagatti S, Sharma R, Hatimota P, Guleria R, Arvind S. Giant thymolipoma. AJR Am J Roentgenol. 2005;185(1):283-4. [CrossRef] [PubMed]
6. Juanpere S, Canete N, Ortuno P, Martínez S, Sanchez, G, Bernado L. A diagnostic approach to the mediastinal masses. Insights Imaging. 2013;4(1):29-52. [CrossRef] [PubMed]
7. Carapinha CP, Wainwright L, Loveland JA. A giant thymolipoma. S Afr J Child Health. 2010;4(1):20-1.

Cite as: Paliwal AK, Jaiswal P, Sharma V. Medical image of the month: thymolipoma. Southwest J Pulm Crit Care. 2019;18(6):152-4. doi: https://doi.org/10.13175/swjpcc018-19 PDF

Medical Image of the Week: Pulmonary Artery Sling

Figure 1. Computerized tomography (CT) of the chest showing the aberrant origin of the left pulmonary artery from the right pulmonary artery creating a pulmonary artery sling with mild tracheal narrowing (arrow).

Figure 2. Cardiac magnetic resonance imaging (MRI) confirming the presence of a pulmonary artery sling with aberrant origin of the left pulmonary artery from the right pulmonary artery.

A 42-year-old year woman with asthma was admitted to the hospital with an asthma exacerbation. The patient complained of dyspnea on exertion, two-pillow orthopnea and bipedal edema. An echocardiogram showed a severely dilated right ventricle (RV) with elevated right ventricular systolic pressure of 71 mmHg. The systolic left ventricular (LV) function was also reduced with an ejection fraction of 45%. Computerized tomography (CT) of the chest showed an aberrant origin of the left pulmonary artery (PA) creating a pulmonary artery sling with mild tracheal narrowing (Figure 1, arrow). Cardiac magnetic resonance imaging (MRI) confirmed the presence of a pulmonary artery sling with the aberrant origin of the left PA from the right PA (Figure 2). Cardiac catheterization showed a mean PA pressure of 46mmHg with LV end diastolic pressure of 12mm Hg. The patient was diagnosed with WHO Group I pulmonary hypertension and started on treatment with sildenafil with a stable outpatient course.

Pulmonary artery sling is an uncommon form of vascular ring. The anomaly is a result of formation of the left PA from the right sixth vascular arch (rather than the left), leading to the left PA arising from the posterior aspect of the right PA (1). Pulmonary artery slings may produce symptoms of airway compression and esophageal compression and usually presents in childhood (2). In asymptomatic cases, a PA sling may mimic a mediastinal mass on chest radiographs and CT and MRI may be used to establish the diagnosis (3).

Abhinav Agrawal MD¹, Stuart L Cohen MD², Rakesh Shah MD², Arunabh Talwar MD FCCP¹

¹Division of Pulmonary, Critical Care & Sleep Medicine, Department of Medicine

²Division of Thoracic Radiology, Department of Radiology

Hofstra-Northwell School of Medicine

New Hyde Park, NY USA

References

1. Casta-er E, Gallardo X, Rimola J, Pallardó Y, Mata JM, Perendreu J, Martin C, Gil D. Congenital and acquired pulmonary artery anomalies in the adult: radiologic overview. Radiographics. 2006 Mar-Apr;26(2):349-71. [CrossRef] [PubMed]
2. Odell DD, Gangadharan SP, Majid A. Pulmonary artery sling: a rare cause of tracheomalacia in the adult. J Bronchology Interv Pulmonol. 2011 Jul;18(3):278-80. [CrossRef] [PubMed]
3. Ganesh V, Hoey ET, Gopalan D. Pulmonary artery sling: an unexpected finding on cardiac multidetector CT. Postgrad Med J. 2009 Mar;85(1001):128. [CrossRef] [PubMed] 

Cite as: Agrawal A, Cohen SL, Shah R, Talwar A. Medical image of the week: pulmonary artery sling. Southwest J Pulm Crit Care. 2017;15:160-61. doi: https://doi.org/10.13175/swjpcc116-17 PDF

Medical Image of the Week: Fast-growing Primary Malignant Mediastinal Mixed Germ Cell Tumor

Figure 1. A: Chest radiograph taken 3 months prior to presentation. B: Chest radiograph showing large mediastinal mass (arrows). C: Coronal view of thoracic CT in soft tissue windows showing the large mediastinal mass (arrows). D: Lateral view of thoracic CT showing large mediastinal mass.

A 28-year-old man presented with progressive hemoptysis for two weeks. He had fever, cough, and night sweats for one month prior to admission that was treated as inflenza, bronchitis and/or pneumonia. He had started to experience anorexia, dysphagia, fatigue, a 30-pound weight loss, panic attacks, and the new onset of hypertension during the 3 months prior to admission. He also had intermittent middle chest pain that was aggravated by coughing for 5 months, but a cardiac catherization two months prior failed to show an abnormality. The chest x-ray and CT scan on this admission demonstrated a 15 cm large anterior mediastinal mass exerting a mass effect on the heart and medistial lymphadenopathy (Figure 1-B,C,D) which were absent on a chest x-ray performed 3 months prior to admission (Figure 1A). Core biopsy and immunohistochemical staining revealed a mixed germ cell tumor with components of seminoma and yolk-sac tumor. He was started on chemotherapy, to which he responded well. The malignant mediastinal germ cell tumor in this case is fast-growing and most likely of extragonadal origin. The majority of tumors occ in men between 20 and 35 years (1). The symptoms of these tumor and nonspecific as described in our case, which may lead to a low index of suspicion of malignant tumor with resultant delayed diagnosis.

Yufei Tian, Stella Pak, and Qiang Nai

Department of Medicine

University of Toledo Medical Center

Toledo, Ohio USA

Reference

1. Carter BW, Marom EM, Detterbeck FC. Approaching the patient with an anterior mediastinal mass: a guide for clinicians. J Thorac Oncol. 2014 Sep;9(9 Suppl 2):S102-9. [CrossRef] [PubMed]

Cite as: Tian Y, Pak S, Nai Q. Medical image of the week: fast-growing primary malignant mediastinal mixed germ cell tumor. Southwest J Pulm Crit Care. 2017;15(3):114-5. doi: https://doi.org/10.13175/swjpcc103-17 PDF

May 2017 Imaging Case of the Month

Prasad M. Panse, MD and Michael B. Gotway, MD

Department of Radiology

Mayo Clinic Arizona

Scottsdale, Arizona USA

Clinical History: Clinical History: A 32-year-old man presented for routine physical examination. His past medical history is unremarkable and the physical examination and basic laboratory data were within normal limits.

A frontal chest radiograph (Figure 1) was performed.

Figure 1: Frontal (A) and lateral (B) chest radiography.

Which of the following statements regarding the chest radiograph is most accurate? (Click on the correct answer to proceed to the second of nine pages)

1. The frontal chest radiograph shows an abnormal mediastinal contour
2. The frontal chest radiograph shows basal predominant fibrotic abnormalities
3. The frontal chest radiograph shows large lung volumes with a cystic appearance
4. The frontal chest radiograph shows multifocal small pulmonary nodules
5. The frontal chest radiograph shows no abnormal findings

Cite as: Panse PM, Gotway MB. May 2017 imaging case of the month. Southwest J Pulm Crit Care. 2017;14(5):201-12. doi: https://doi.org/10.13175/swjpcc055-17 PDF 

Medical Image of the Week: Esophageal Cancer

Chandramohan Meenakshisundaram, MD 

Nanditha Malakkla, MD 

Saint Francis Hospital

Evanston, IL

Figure 1. Admission chest x-ray showing hyper-aerated lung fields and consolidation at the left lung base.

Figure 2. Video of selected images from thoracic CT scan in soft tissue windows showing large mediastinal mass with extravasation of contrast.

Figure 3. Views from endoscopy showing a large mass and the perforation site.

A 66-year-old Asian man with no significant past medical history was admitted with 1 week history of worsening retrosternal sharp chest pain, dyspnea on moderate exertion, and cough productive of brownish sputum. He also complained of some difficulty swallowing, decreased appetite and weight loss for the past 3 months. PPD was negative in the past. Vitals signs were significant for tachycardia and low grade fever. On physical exam he was cachectic and lung auscultation revealed bilateral scattered wheezes. Basic labs including complete blood count and comprehensive metabolic panel were unremarkable. EKG showed sinus tachycardia, serial troponin I was negative and chest x-ray revealed bilateral hyper-aerated lung fields and consolidation over the left lung base (Figure 1). He was started on antibiotics and bronchodilators. Since he continued to have chest pain and remained tachycardic, CT angiography of chest and abdomen (with IV and oral contrast) was done which revealed extravasation of contrast material into the mediastinum in the mid esophageal region representing rupture, a large mediastinal mass concerning for an abscess, and extensive infiltrates in the left lower lobe (Figure 2). During left thoracotomy, a large amount of necrotic material and phlegmon was seen in the mediastinum with adjacent area of lung necrosis which was drained and debrided. Upper GI endoscopy revealed a large mass in the mid-esophagus with perforation for which stenting was done (Figure 3). Pathology of phlegmon revealed squamous cell carcinoma with extensive necrosis. Culture of the fluid grew both viridians streptococci and anaerobes and he was started on broad spectrum antibiotics. His post-operative course was complicated and later he elected hospice care.

Reference as: Meenakshisundaram C, Malakkla N. Medical image of the week: eosphageal cancer. Southwest J Pulm Crit Care. 2014;9(5):295-6. doi: http://dx.doi.org/10.13175/swjpcc151-14 PDF

January 2014 Imaging Case of the Month

Michael B. Gotway, MD

Department of Radiology

Mayo Clinic Arizona

Scottsdale, AZ

Clinical History

A 77-year-old man presented for an executive health physical. His past medical history was significant for coronary artery disease, renal stones, gout, and a left nephrectomy for clear cell renal carcinoma 17 years earlier. Chest radiography (Figure 1) was performed. Prior chest radiographs from the previous year (Figure 2) and 7 years earlier (Figure 3) are shown for comparison.

 

Figure 1. Frontal (A) and lateral (B) chest radiography. 

 

 Figure 2. Frontal (A) and lateral (B) chest radiography performed one year prior to presentation. 

Figure 3. Frontal chest radiography performed 7 years prior to presentation.

Which of the following statements regarding the chest radiograph is most accurate? (Click on the correct answer to move to next panel)

1. The chest radiograph shows a mass
2. The chest radiograph shows an unusual cardiac configuration
3. The chest radiograph shows basal predominant linear opacities suggesting fibrosis
4. The chest radiograph shows multifocal ground-glass opacity and consolidation associated with linear and reticular abnormalities
5. The chest radiograph shows multiple nodules

Reference as: Gotway MB. January 2014 imaging case of the month. Southwest J Pulm Crit Care. 2014;8(1):27-40. doi: http://dx.doi.org/10.13175/swjpcc002-14 PDF

November 2011 Case of the Month

Michael B. Gotway, MD

Associate Editor Imaging

Reference as: Gotway MB. November 2011 Case of the month. Southwest J Pulm Crit Care 2011;3: 154-8. (Click here for PDF version of manuscript)

Clinical History

A 47-year-old woman presents with complaints of hemoptysis. The hemoptysis was witnessed and was massive, resulting in anemia. A frontal and lateral chest radiograph (Figures 1A and B) was performed.

Figure 1: Frontal and lateral chest radiograph

What is the main finding on the chest radiograph? How would you describe the finding?

1. A solitary pulmonary nodule
2. An anterior mediastinal mass
3. Basal predominant linear and reticular abnormalities suggesting fibrotic lung disease
4. An intracavitary mass superimposed on a background of interstitial abnormality
5. Bilateral pleural effusions and thickening