Systematic Approach To Fat Containing Lesions Of The Thorax

Transcription

1 Systematic Approach To Fat Containing Lesions Of The Thorax Ernest Yushvayev, Daniel Droukas, Robert Perone. Northwell Health

2 Disclosure statement We have no actual or potential conflicts of interest in relation to this electronic exhibit.

3 Goals 1. To become familiar with a variety of fat containing intra-thoracic lesions. 2. Learn to easily narrow the differential diagnosis based on the imaging characteristics and location within specific compartments of the thorax.

4 Objectives 1. To identify fat containing lesions and their imaging characteristics. 2. To review intrathoracic examples of such lesions.

5 Target Audience This electronic presentation is geared towards Radiology residents.

6 Imaging of fat and patterns of distribution Macroscopic fat on CT Patterns of fat distribution -10 to -100 Hounsfield units. Fat on MRI Hyperintense on T1 weighted images and intermediate to hyperintense on T2 weighted images. Fat on Ultrasound Echogenic Homogenous Focal Heterogenous

7 Endobronchial Lesions FAT? NO YES Bronchogenic adenocarcinoma Squamous cell carcinoma Small cell carcinoma Bronchial carcinoid Endobronchial metastasis Leiomyoma Squamous cell papilloma Pleomorphic adenoma Granular cell tumor Amyloidoma Fibroepithelial polyp Hamartoma Lipoma Image courtesy of e-anatomy, Micheau A, Hoa D,

8 ENDOBRONCHIAL FAT CONTAINING LESIONS Hamartoma Symptoms: Obstructive in nature, including chronic cough, hemoptysis and fever. Contents: Cartilage, fat, fibrous and epithelial tissue. CT findings: Postobstructive changes. Smooth bordered endobronchial lesion with alternating foci of fat and calcification. Lipoma Benign. Predilection for mainstem bronchi. Symptoms: Post obstructive symptoms. Chest pain, dyspnea, fevers, pneumonia. CT findings: Postobstructive changes. Pedunculated homogenous lesion with fat attenuation (approximately -100 HU) Figure 1: Endobronchial hamartoma: Heterogenous endobronchial lesion with areas of fat attenuation in the right middle lobe bronchus. Post obstructive atelectasis is noted in the right middle lobe. Case courtesy of H. Page McAdams, MD, Duke University Medical Center, Durham, NC.

9 Intraparenchymal Lesions FAT? NO YES Broad differential including malignant, benign, infectious, vascular and inflammatory etiologies. Hamartoma Lipoma Lipoid Pneumonia Image courtesy of e-anatomy, Micheau A, Hoa D,

10 INTRAPARENCHYMAL FAT CONTAINING LESIONS Hamartoma A B Benign. Male Predominance of 2:1 to 3:1. Location: Most common in the hilar region. CT findings: Soft tissue mass or nodule Popcorn calcification (5-50%) Focal or generalized fat (50%) Lipoma Origin: Adipose tissue. Asymptomatic, rare and benign. CT findings: Well circumscribed lesion. Homogenous fat attenuation. C D Figures 2 a,b,c,d: Intraparenchymal Hamartoma. Right hilar mass with punctate focus of calcification and focal areas of fat.

11 INTRAPARENCHYMAL FAT CONTAINING LESIONS Lipoid Pneumonia Etiology: Exogenous: Acute or chronic aspirations of oils. Endogenous: Secondary to a central obstructive lesion. Pathophysiology: Macrophage phagocytosis within alveoli and eventual transport to interlobular septa. Local edema and inflammation which may progress to fibrosis. CT findings: Predominantly involve middle and lower lobes. Mass like ground glass or consolidative opacities with areas of fat attenuation. Crazy paving pattern may be seen. Fibrotic changes such as traction bronchiectasis. A B Figure 3 a,b: Lipoid Pneumonia. Mass like consolidation in the left lower lobe with focal area of fat.

12 Mediastinal Lesions FAT? NO YES Anterior Mediastinum -Thymic Masses -Germ Cell Tumors -Thyroid Masses -Lymph Node Masses -Vascular -Parathyroid Masses MIddle Mediastinum -Lymph Node Masses -Duplication Cyst -Vascular Posterior Mediastinum -Neurogenic Masses -Vascular -Duplication Cyst -Neurenteric cyst -Lymph node masses -Thymolipoma -Teratoma and Teratocarcinoma -Mesenchymal lesions such as lipomatosis and lipoma. -Extramedullary Hematopoiesis -Esophageal lipoma -Lipoblastoma -Liposarcoma Image courtesy of e-anatomy, Micheau A, Hoa D,

13 Figure 4a MEDIASTINAL FAT CONTAINING LESIONS A Lipoma Origin: Mesenchymal tumor originating from adipose tissue. Symptoms: Secondary to mass effect. Location: Most common in anterior mediastinum CT findings: Well circumscribed mass Homogenous fat attenuation Lipomatosis B Figure 4b Seen in exogenous steroid use and obesity. CT Findings: Unencapsulated Infiltrating fat Figure 4a: Mediastinal Lipomatosis. Figure 4b: Mediastinal Lipoma.

14 MEDIASTINAL FAT CONTAINING LESIONS A Figure 5a Thymolipoma Rare and benign anterior mediastinal lesion Symptoms: Mass effect. Typically asymptomatic. CT findings: Well delineated mass Fat attenuation mixed with normal thymic tissue Connection to thymus or superior mediastinum can often be demonstrated. B Figure 5b Figures 5a, 5b: Thymolipoma: Well circumscribed mass in the anterior mediastinum, anterior to the aortic arch which demonstrates mixed fat and soft tissue density.

15 MEDIASTINAL FAT CONTAINING LESIONS A Figure 6a: Teratoma: Anterior mediastinal cystic mass with soft tissue, fluid, fat and calcium components. Teratoma Origin: Germ Cell Mediastinal Location: Typically Anterior. Histology: Mature ( Benign) Immature ( Malignant) CT findings: Heterogeneous cystic lesion Smooth Contoured, encapsulated, multicystic Calcification. Soft tissue component. Fat component( 76% of cases) Fat fluid level. Teratocarcinoma Male Predilection CT findings: Above findings with following differences Poorly defined, irregular and nodular margins. Thick enhancing capsule with contrast admin. B Figure 6b: Teratocarcinoma:Anterior mediastinal mass with soft tissue and fat component. Nodular and irregular margin.

16 MEDIASTINAL FAT CONTAINING LESIONS Lipoblastoma Origin: Mesenchymal Age: Early childhood Location: Typically in the extremities ( 70%). Can also be seen in the mediastinum as well as other locations.. Symptoms: Secondary to mass effect. CT Findings: Mostly fatty mass Well defined margins Can have septa and nodularity Intratumoral stranding Cystic changes can be seen. MRI Findings: Intratumoral streaks and whorls Figure 4a A B Figure 4b Figure 7a:Lipoblastoma. 7 year old patient. CT shows a heterogenous fatty lesion. Thoracic inlet is a characteristic location for lipoblastoma.case courtesy of Mark J. Kransdorf, MD, Mayo Clinic, Jacksonville, Fla. Figure 7b:Lipoblastoma. Coronal T1 weighted image. Heterogeneous fatty lesion at the right thoracic inlet. Internal streaks and whorls are demonstrated which are representative of its characteristic fibrovascular network. Case courtesy of Mark J. Kransdorf, MD, Mayo Clinic, Jacksonville, Fla.

17 Cardiac Lesions FAT? NO YES Myxoma Papillary fibroelastoma Rhabdomyoma Fibroma Hemangioma Paraganglioma Sarcomas Primary cardiac lymphoma Pericardial Mesothelioma Lipoma Liposarcoma Lipomatous Hypertrophy of the interatrial septum Arrhythmogenic right ventricular dysplasia Image courtesy of e-anatomy, Micheau A, Hoa D,

18 CARDIAC FAT CONTAINING LESIONS Lipoma Location: Typically Extra Myocardial. Can be either subendocardial or subepicardial. Symptoms: Secondary to mass effect. Include: anginal pain, arrhythmia, sudden death and CHF. CT findings: Encapsulated oval fat attenuation mass. Figure 8: Cardiac Lipoma: Well marginated fat attenuation lesion along the right atrial wall.

19 CARDIAC FAT CONTAINING LESIONS Liposarcoma Malignant Location: Typically right side of heart. Behavior: Local invasion or metastasis. Histology: Well differentiated, myxoid, round cell, pleomorphic. Symptoms: Chest pain, dyspnea, arrhythmia, symptoms of CHF. Imaging findings: Mass with varying fat content ranging from homogeneously fatty to nearly complete soft tissue attenuation. Signs of invasion or infiltration. Calcification. Adjacent mediastinal structure may have poorly defined margins. A B Figure 9a, 9b: Well differentiated liposarcoma: Axial T2 and coronal T1 weighted MR images demonstrate a lobular hyperintense mass along the right heart border. Case courtesy of Mark J. Kransdorf, MD, Mayo Clinic, Jacksonville, Fla.

20 CARDIAC FAT CONTAINING LESIONS A B Lipomatous Hypertrophy of the Interatrial Septum Benign Unencapsulated fat containing lesion in the interatrial septum. No extracardiac or intracavitary component. Symptoms: Asymptomatic. Maybe associated with arrhythmias or sudden cardiac death. Imaging findings: Fat containing lesion in the interatrial septum. Characteristic dumbbell shape. Nonenhancing. Well marginated, non encapsulated. Relative sparing of oval fossa. Moderate FDG uptake on PET/CT Figure 10a: Lipomatous hypertrophy of the interatrial Septum. Well marginated fat containing lesion in the interatrial septum. Figure 10b shows a T1 weighted MRI image in which sparing of the oval fossa and characteristic dumbbell shape is demonstrated.

21 CARDIAC FAT CONTAINING LESIONS Arrhythmogenic Right Ventricular Dysplasia (ARVD) Fatty or fibrofatty replacement of the right ventricular myocardial tissue. Location: Right ventricular apex is the most commonly affected. Symptoms: Ventricular arrhythmias or sudden cardiac death. Imaging findings: Fatty or fibrofatty replacement of the right ventricular myocardium. Diffuse or focal right ventricular dilatation. Right ventricular wall thinning MR cine imaging can show wall motion abnormalities and lack of normal systolic thickening. A B Figure 11a ARVD: Axial Fast Spin echo T2 weighted MR image demonstrates fatty replacement of the myocardium in the right ventricular apex. ( Black Arrows) Case courtesy of David A. Lynch, MD, University of Colorado Health Sciences Center, Denver. Figure 11b, c ARVD: Cine MR images at end systole (b) and end diastole(c) demonstrate lack of normal systolic wall thickening and akinesis of the right ventricular wall. Case courtesy of David A. Lynch, MD, University of Colorado Health Sciences Center, Denver. C

22 Solid Pleural and Extrapleural Lesions FAT? NO YES -Pleural Thickening -Localized fibrous tumor of the pleura -pleural Metastasis -Lymphoma -Lung Cancer with chest wall invasion -Splenosis -Mesothelioma -Askin tumor -Lipoma -Hiatal Hernia -Bochdalek Hernia -Morgagni Hernia -Juxtacaval Fat Image courtesy of e-anatomy, Micheau A, Hoa D,

23 PLEURAL FAT CONTAINING LESIONS Lipoma Benign encapsulated fatty tumor Origin: submesothelial layer of the parietal pleura. Symptoms: Typically asymptomatic. Can be associated with with cough, back pain, exertional dyspnea. CT findings: Well circumscribed. Homogenous fat attenuation. Figure 12 Pleural Lipoma

24 EXTRAPLEURAL FAT CONTAINING LESIONS Figure 4a A Morgagni Hernia Herniation of abdominal contents through a diaphragmatic defect termed foramen of Morgagni. Location: Anterior and retrosternal. Right sided (90% of the cases) Hernia contents: omentum> colon>stomach> liver >small intestine. B Figure 4b CT findings: Sagittal or coronal images can assist in demonstrating the diaphragmatic defect. Figure 13 a, b: Morgagni Hernia. Axial and sagittal images demonstrate right sided, anterior and retrosternal herniation of bowel and omental fat. Sagittal image demonstrates diaphragmatic defect.

25 EXTRAPLEURAL FAT CONTAINING LESIONS A Figure 4a Bochdalek Hernia Developmental defect in posterior portion of the diaphragm results in herniation of abdominal contents. Presentation: Infancy Laterality: Left sided ( 70-90% of cases) Contents: Typically fat and omental tissue. Retroperitoneal and intraperitoneal contents may also herniate. CT findings: Sagittal or coronal images can assist in demonstrating the diaphragmatic defect. B Figure 4b Figure 14 a,b: Bochdalek Hernia. Axial and coronal images demonstrate right sided paraspinal lesion with fat attenuation. Coronal image demonstrates the diaphragmatic defect.

26 Figure 4a EXTRAPLEURAL FAT CONTAINING LESIONS Juxtacaval Fat Focal fat collection medial to and adjacent to the lumen of the IVC near the hepatic venous junction. CT appearance: Focal lesion with fat density adjacent to and medial to IVC Can appear to be intracaval. Attributed to subdiaphragmatic narrowing of the IVC. Figure 4b Figure 15: Juxtacaval Fat. Homogeneous lesion with fat attenuation, appears to be within the lumen of the IVC at the level of the hepatic venous junction.

27 Conclusion Identifying fat containing intra-thoracic lesions and their anatomic location within the thorax can assist the radiologist in narrowing the differential so that a more accurate radiologic diagnosis can be made thus facilitating the implementation of prompt and appropriate patient management.

28 References Betancourt SL, Martinez-Jimenez S, Rossi S, Truong MT, Carrillo J, Erasmus J. Lipoid Pneumonia: Spectrum of Clinical and Radiologic Manifestations : American Journal of Roentgenology: Vol. 194, No. 1 (AJR). Lipoid Pneumonia: Spectrum of Clinical and Radiologic Manifestations : American Journal of Roentgenology: Vol. 194, No. 1 (AJR). Published Accessed December 12, Gaerte SC, Meyer CA, Winer-Muram HT, Tarver RD, Conces DJ. Fat-containing Lesions of the Chest. RadioGraphics. 2002;22(suppl_1). doi: /radiographics.22.suppl_1.g02oc08s61. Gaillard F. Liposarcoma Radiology Reference Article Radiopaedia.org. Radiopaedia Blog RSS. Accessed December 12, Grebenc ML, Christenson MLRD, Burke AP, Green CE, Galvin JR. Primary Cardiac and Pericardial Neoplasms: Radiologic-Pathologic Correlation. RadioGraphics. 2000;20(4): doi: /radiographics.20.4.g00jl Hussein-Jelen T, Bankier AA, Eisenberg RL. Solid Pleural Lesions. American Journal of Roentgenology. 2012;198(6). doi: /ajr Mediastinum - Masses. The Radiology Assistant : Mediastinum - Masses. Accessed December 12, Nasseri F, Eftekhari F. Clinical and Radiologic Review of the Normal and Abnormal Thymus: Pearls and Pitfalls. RadioGraphics. 2010;30(2): doi: /rg Roberts CC. Lipoblastoma/Lipoblastomatosis. STATdx. Accessed December 12, Shin N-Y, Kim M-J, Chung J-J, Chung Y-E, Choi J-Y, Park Y-N. The Differential Imaging Features of Fat-Containing Tumors in the Peritoneal Cavity and Retroperitoneum: the Radiologic- Pathologic Correlation. Korean Journal of Radiology. 2010;11(3):333. doi: /kjr Webb R, Brant W, Major N. Fundamentals of Body CT. Elsevier; 2014 Weerakkody Y. Tracheal and endobronchial lesions Radiology Reference Article Radiopaedia.org. Radiopaedia Blog RSS. Accessed December 12, 2016.

29 Author Contact information Ernest Yushvayev