Sarcoid: Cardiac and Chest Manifestations
Review of high-yield radiology manifestations of sarcoidosis in the heart and lungs for the ABR Core Exam. Check out the associated free downloadable study guide available on this website under “study guides”. Prepare to succeed!
Study Guide/Show Notes:
Sarcoid: Cardiac and Chest Manifestations
Sarcoidosis: A multi-systemic disease with non-caseating granulomas. Idiopathic disease thought to be inhalational with unknown antigen. Both sarcoid and TB are inhaled first, then go from lymphatics to other sites of the body.
Cardiac sarcoidosis:
About 5% of sarcoid cases have cardiac involvement. Cardiac involvement increases mortality risk.
What are some typical imaging manifestations of sarcoidosis on cardiac MRI?
Increased myocardial T2 signal with delayed gadolinium enhancement in the mid or epicardial portions of the left ventricular myocardial wall in a non-coronary distribution. Cardiac sarcoidosis rarely involves the right ventricle or the papillary muscles. Cardiac sarcoid granulomas can also cause myocardial aneurysms as well.
Delayed enhancement of sarcoidosis can be in any location of LV and can appear to be diffuse, patchy, nodular and/or linear. Most commonly sarcoid enhancement will be in the mid-myocardial or subepicardial regions.
What can be done to confirm cardiac sarcoidosis if imaging manifestations are suggestive?
Endomyocardial biopsy to evaluate for caseating granulomas in the myocardium.
What nuclear medicine study can be performed for evaluation of cardiac sarcoidosis?
Dedicated FDG PET/CT of the heart
What patient preparation is necessary prior to cardiac FDG PET/CT for evaluation of cardiac sarcoidosis and why is patient preparation necessary?
The patient must have a low carbohydrate diet the day before the scan and fast overnight to switch the cardiac metabolism to free fatty acid metabolism to suppress normal cardiac glucose uptake. If normal cardiac glucose uptake is suppressed, only portions of the heart involved with sarcoidosis should take up the FDG. This allows you to unmask the sarcoidosis from the normal cardiac FDG uptake. Additionally, IV heparin can be administered as part of patient preparation prior to scanning as this may also suppress normal cardiac glucose uptake.
What are common entities that can cause epicardial delayed enhancement on MRI?
Sarcoidosis, myocarditis, Chagas disease.
What are common entities that can cause delayed enhancement of the mid myocardial wall?
Amyloid, sarcoid, hypertrophic cardiomyopathy
What are common entities that can cause subendocardial delayed enhancement?
Myocardial infarction/scar if vascular distribution (ischemic cardiomyopathy) and amyloid if non-vascular or diffuse distribution.
Can you have cardiac sarcoidosis without lung involvement of sarcoidosis?
Yes. However, if you see mediastinal/hilar adenopathy and see characteristic myocardial delayed enhancement I would think of sarcoid until proven otherwise for board exams. “Hilar plus heart equals sarcoid”.
Can cardiac sarcoidosis cause a restrictive cardiomyopathy?
Yes. Differential for restrictive cardiomyopathy includes sarcoid, amyloid, Loeffler’s eosinophilic endocarditis, hemochromatosis.
How can one differentiate between cardiac sarcoidosis and myocarditis on cardiac MRI?
These can look identical on cardiac MRI so the best way to differentiate is by presence of coexistent lymphadenopathy/lung disease of sarcoidosis and patient history. If you see coexistent lymphadenopathy/lung disease, think sarcoid. If you don’t see these then differential includes sarcoid and myocarditis.
Pulmonary Sarcoidosis:
Sarcoidosis typically presents with what type of pulmonary nodule pattern: perilymphatic, random, or centrilobular?
Sarcoid typically presents with perilymphatic nodules.
What are typical early and late imaging characteristics of pulmonary sarcoidosis?
Early: Upper lobe predominant perilymphatic nodules. Lambda sign of mediastinal/hilar lymphadenopathy (1-2-3 pattern) which is bilateral hilar and right paratracheal lymphadenopathy.
Late: Upper lobe fibrosis, traction bronchiectasis.
Does end-stage pulmonary sarcoidosis present with honeycombing?
Classically no. Classis sarcoid is lack of honeycombing despite end stage lung disease elsewhere.
What superimposed disease process can form in patients with end stage pulmonary sarcoidosis?
Aspergillomas can commonly form in cavities in lungs of patients with end stage sarcoidosis.
Besides CT imaging or chest radiographs the Lambda sign can also be shown on what type of nuclear medicine scan?
Gallium 67 scan. Degree of uptake on gallium scan has been shown to correlate with disease activity and severity. Gallium uptake is about 90% sensitive for active pulmonary sarcoidosis and scans will be negative with inactive sarcoidosis. Gallium can therefore also guide site of biopsy for highest yield.
What is another sign on a Gallium scan (extrapulmonary) that is classic for sarcoidosis?
Panda sign: Uptake in the lacrimal glands, nasopharynx, and parotid glands that looks like the ears, eyes, and nose of a panda’s face.
What is the CT galaxy sign of pulmonary sarcoidosis?
Upper lobe predominant masses with satellite perilymphatic nodules. The masses are a conglomerate of nodules that have coalesced.
What are typical age/demographic characteristics that you would expect for sarcoidosis on a board exam?
20-40-year-old person, most classically an African American female (but not exclusively). But if they give you this history and show you a chest CT you should already be considering the possibility of sarcoid. Most sarcoid patients will become symptomatic prior to 40 years old.
What organ is the most affected in sarcoidosis?
Lungs
What are some laboratory values that are typical of pulmonary sarcoidosis?
Elevated ACE levels, hypercalcemia.
How many stages of pulmonary sarcoid are there?
4 stages including a stage 0
What are pulmonary imaging manifestations for each stage on a CXR?
Stage 0: Normal on chest radiograph
Stage 1: hilar/mediastinal nodes only (50% of cases present here)
Stage 2: Parenchymal disease plus hilar/mediastinal nodes (30% of cases)
Stage 3: ONLY parenchymal disease (nodes burned out)
Stage 4: End stage pulmonary fibrosis with irreversible scarring and distortion. This is also termed progressive massive fibrosis (other causes include silicosis and TB)
What is the treatment for end-stage pulmonary sarcoidosis?
Pulmonary transplant
Can sarcoid recur after pulmonary transplant?
Yes, sarcoid is perhaps the most common disease that can recur after pulmonary transplant, perhaps in up to 35% of cases.
Is sarcoidosis on the differential for fibrosing mediastinitis?
Yes, although histoplasmosis is the most classic cause of fibrosing mediastinitis, other causes include sarcoid, TB, radiation.
Does pulmonary sarcoidosis typically have uptake on FDG PET/CT?
Yes, sarcoid inflammation causes FDG uptake and is a cause of a false-positive FDG scan in the lungs along with other infectious/inflammatory processes to include TB, fungal infection, rheumatoid nodules, etc.
Can sarcoid cause tracheal thickening?
Yes, typically of the circumferential type, NOT the cartilaginous type. If you see circumferential tracheal thickening with lymphadenopathy and upper lobe predominant perilymphatic nodules, you should think of sarcoidosis as the cause. Differential diagnosis of circumferential tracheal thickening includes amyloidosis (bulky calcified nodules and/or cysts with nodular septal thickening) and granulomatosis with polyangiitis (cavitary pulmonary nodules with pulmonary hemorrhage). TB and IBD also on differential.
What is the association of sarcoidosis with cigarette smoking?
Cigarette smoking decreases the incidence of sarcoidosis (and hypersensitivity pneumonitis).
