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Case of the Day – Chest Darin White MDCM FRCPC Department of Radiology, Mayo Clinic 76th Annual Scientific Meeting Canadian Association of Radiologists Montreal, QC April 26, 2013

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Disclosures • Relevant Financial Disclosures •  None

• Off Label Use Disclosures •  None

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History • 46 year-old male • Progressive dyspnea on exertion • New small amounts of hemoptysis for 2 months

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Differential Diagnosis – Unilateral Pulmonary Interstitial Pattern •  ACUTE

•  Infection •  Edema •  Aspiration •  Resolving hemorrhage

•  Airspace opacity superimposed on already abnormal lung (i.e. emphysema, fibrosis, etc.)

•  CHRONIC •  Recurrent aspiration/

infection •  Radiation fibrosis •  Lymphangitic

carcinomatosis •  Pulmonary venous

obstruction •  Unilateral lung

transplant •  Other rare

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Differential Diagnosis •  NEOPLASTIC

•  Bronchogenic carcinoma

•  Metastatic disease •  Lymphoma

•  NON-NEOPLASTIC •  Fibrosing mediastinitis •  IgG4-related disease

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Subsequent Evaluation •  18F-FDG PET/CT

•  Mildly increased metabolic activity in subcarinal and para-aortic lymph nodes (SUVmax = 3.6)

•  Low level 18F-FDG activity in region of left hilar soft tissue thickening

•  EBUS-guided Biopsy •  Negative for malignancy

•  Serology •  Histoplasma capsulatum

antibody positive

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Answer

Fibrosing Mediastinitis

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Fibrosing Mediastinitis • Also referred to as mediastinal fibrosis or

sclerosing mediastinitis

• Rare benign proliferation of fibrous tissue within the mediastinum •  Pathologically, a spectrum from loose fibromyxoid

tissue to dense collagen with a variable inflammatory cellular infiltrate

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Fibrosing Mediastinitis – Etiology •  Granulomatous infection

•  Histoplasma capsulatum •  Tuberculosis, actinomycosis,

blastomycosis, aspergillosis…

•  Non-infectious granulomatous disease •  Sarcoidosis, silicosis, Behcet’s

•  Immunologic/Autoimmune •  Collagen vascular disease, IgG4-

related disease, multisystem fibrosis

•  Malignancy

•  Iatrogenic •  methysergide, radiation

•  Trauma

•  Idiopathic

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Fibrosing Mediastinitis – Presentation • Variable age at presentation •   ♂=♀ •  Signs and symptoms related to compression or

obstruction of mediastinal or hilar structures •   Cough, dyspnea, recurrent infection, chest pain, hemoptysis,

superior vena cava syndrome, dysphagia, hoarseness, diaphragmatic paralysis, Horner syndrome, chylothorax…

•  Constitutional symptoms •   Fever, weight loss, malaise

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Fibrosing Mediastinitis – Imaging •  Chest Radiographs

•  mediastinal widening •  distortion of mediastinal lines

and stripes •  hilar enlargement •  +/- calcification •  Sequelae:

•  airway narrowing, post-obstructive atelectasis/consolidation

•  pulmonary venous hypertension, pulmonary edema

•  vascular asymmetry, pulmonary infarcts

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Fibrosing Mediastinitis – Imaging •  CT

•  infiltrative mediastinal/hilar soft tissue thickening or mass

•  focal (82%) or diffuse (18%) •  calcification (60-90%) •  variable enhancement •  Sequelae

•  compression/obstruction of central airways, central vessels, esophagus

•  atelectasis, consolidation, edema, infarcts

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Fibrosing Mediastinitis – Imaging •  MRI

•  typically intermediate T1 and heterogeneous T2 signal intensity

•  often regions of T2 hypointensity

•  inferior to CT for detection of calcification

•  heterogeneous enhancement post-gadolinium

•  Sequelae •  as demonstrated on CT

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Fibrosing Mediastinitis – Imaging •  Nuclear Medicine •  18-FDG PET

•  variable metabolic activity within and between lesions

•  Ventilation/Perfusion •  perfusion defects reflecting

pulmonary arterial or venous obstruction

•  lobar/segmental ventilation defects or air trapping reflecting airway involvement

Ventilation Perfusion

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Summary • Fibrosing mediastinitis should be considered in

the setting of localized mediastinal soft tissue thickening associated with vascular and/or airway compromise. • Accompanying calcification further suggests the

diagnosis. •  In the correct clinical setting, such as positive

Histoplasma capsulatum serology and no known malignancy, CT findings may obviate the need for biopsy.

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Questions?

white.darin@mayo.edu

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Review •  At the conclusion of this session, participants should

be able to: 1.  Provide a differential diagnosis for a unilateral pulmonary

interstitial pattern. (CanMEDS Roles: Medial Expert) 2.  Describe the typical imaging features and differential

diagnosis of fibrosing mediastinitis. (CanMEDS Roles: Medical Expert)

3.  List at least four causes of fibrosing mediastinitis. (CanMEDS Roles: Medical Expert)

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References •  McNeeley MF, Chung JH, Bhalla S, Godwin JD. Imaging of

granulomatous fibrosing mediastinitis. AJR. 2012; 199(2):319-327.

•  Rossi SE, McAdams HP,Rosado-de-Christenson ML, Franks TJ, Galvin JR. Fibrosing mediastinitis. Radiographics. 2001; 21(3):737-757.

•  Franquet T. Mediastinitis. In: Muller NL, Silva CIS, eds. Imaging of the Chest. Philadelphia, PA: Saunders Elsevier; 2008: 1457-1472.