Thoracic Imaging 2003 - Society of Thoracic Radiology
Thoracic Imaging 2003 - Society of Thoracic Radiology
Thoracic Imaging 2003 - Society of Thoracic Radiology
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SUNDAY<br />
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application. The untreated patient with sarcoid will improve 50<br />
to 90 percent <strong>of</strong> the time with Radiographic stage 1 disease. The<br />
untreated patient with Stage 2 disease will improve 30 to 70<br />
percent <strong>of</strong> the time. Only 10 to 20 percent <strong>of</strong> untreated patients<br />
with Stage 3 disease will improve, and there is no improvement<br />
in those with untreated Stage 4 disease, [5]. It is important to<br />
note that there may be considerable discrepancy between the<br />
severity <strong>of</strong> the radiographic abnormalities and the patient’s<br />
symptoms, [5].<br />
The clinical diagnosis <strong>of</strong> sarcoid requires a compatible clinical<br />
and radiographic presentation, biopsy evidence <strong>of</strong> sarcoid<br />
granulomas, usually from transbronchial biopsies <strong>of</strong> the lung,<br />
and the exclusion <strong>of</strong> other diseases capable <strong>of</strong> producing a similar<br />
clinical, radiographic, and histological picture, [1-5].<br />
Systemic corticosteroid therapy is clearly indicated for cardiac<br />
disease, neurological disease, eye disease that is refractory<br />
to topical therapies, and hypercalcemia, [1]. Most physicians<br />
feel that progressive symptomatic pulmonary and extrapulmonary<br />
disease should be treated with systemic corticosteroids,<br />
[1]. Cytotoxic agents, antimalarial agents, and lung transplantation<br />
are useful in select patients with advanced sarcoid, [1].<br />
The diagnostic yield <strong>of</strong> endomyocardial biopsies is low in<br />
sarcoid patients. Sarcoid patients with symptomatic cardiac dysfunction,<br />
ECG abnormalities, thallium 201 imaging defects, or<br />
MR evidence <strong>of</strong> myocardial disease should be presumed to have<br />
cardiac sarcoidosis in the presence <strong>of</strong> a negative endomyocardial<br />
biopsy, [1]. It is important in older sarcoid patients to<br />
exclude coronary artery disease as cause <strong>of</strong> their cardiac illness.<br />
Sarcoid is a multisystem disease and, for this reason, careful<br />
clinical evaluation <strong>of</strong> the entire patient must be done. This clinical<br />
review includes the peripheral lymph nodes, skin, spleen,<br />
liver, eyes, central nervous system, musculoskeletal system, gastrointestinal<br />
tract, bone marrow, parotid glands, reproductive<br />
organs, kidneys, and the endocrine system, [1-5].<br />
Physiology<br />
The pulmonary physiology <strong>of</strong> sarcoid is usually a predominantly<br />
restrictive ventilatory process, with reductions in vital<br />
capacity (VC) and diffusion capacity (DLCO), [4]. Physiology<br />
testing cannot distinguish alveolitis from fibrosis, [4]. Serial<br />
physiological testing is quite valuable in monitoring the course<br />
<strong>of</strong> an individual patient’s pulmonary sarcoid, [4]. An obstructive<br />
component <strong>of</strong> the lung physiology is detected in one-third or<br />
more <strong>of</strong> sarcoid patients with lung involvement with reductions<br />
in FEVI and expiratory flow rates, [4]. Central and small airway<br />
involvement accounts for the obstructive physiology observed in<br />
these sarcoid patients.<br />
Typical Radiographic and CT Observations in the Thorax<br />
The most common radiographic presentation is Stage 1 sarcoid<br />
with bilateral symmetric hilar lymphadenopathy and mediastinal<br />
lymphadenopathy in an asymptomatic patient, [5].<br />
Mediastinal lymph node enlargement usually is seen in the right<br />
paratracheal, aortopulmonary window, and subcarinal regions.<br />
Anterior mediastinal lymph node enlargement is unusual in sarcoid<br />
unlike lymphoma patients, [5]. CT demonstrates lymphadenopathy<br />
better than radiography and <strong>of</strong>ten demonstrates<br />
additional regions <strong>of</strong> lymph node involvement. CT is more sensitive<br />
than radiography for the detection <strong>of</strong> lymph node calcifications<br />
in sarcoid, [5].<br />
The typical radiographic observations in Stage 2 or 3 sarcoid<br />
are nodules, linear/reticular opacities and ground glass opacities<br />
with a mid and upper lung zone distribution [5]. HRCT examination<br />
demonstrates a perilymphatic distribution <strong>of</strong> irregular,<br />
small discrete nodules, 2 to 10 mm in size, that predominate in<br />
both the mid and upper lung zones and in the central portion <strong>of</strong><br />
the lung. This perilymphatic distribution <strong>of</strong> nodules results in<br />
nodules that are associated with the bronchovascular structures,<br />
interlobular septae, and pleural surfaces. Peribronchial wall<br />
thickening is common on HRCT, as well as interlobular septal<br />
thickening and ground glass opacities. Nodules larger than 10<br />
mm in size may be seen but are less common.<br />
Radiographic Stage 4 sarcoid has marked upper lobe volume<br />
loss, architectural distortion <strong>of</strong> the lung, conglomerant mass formation,<br />
cyst formation, honeycombing, traction bronchiectasis,<br />
and emphysema, [51. Pulmonary fibrosis and honeycombing<br />
with an upper lobe predominance develops in 20 % <strong>of</strong> sarcoid<br />
patients. HRCT examinations show similar findings but to better<br />
advantage than radiography.<br />
Plain radiography and CT may show severe bronchial stenosis<br />
or irregularity in patients with endobronchial sarcoid. Central<br />
airway observations on CT include regular or irregular bronchial<br />
wall thickening, luminal narrowing or occlusion, and displacement<br />
<strong>of</strong> central bronchial structures by adjacent lymphadenopathy,<br />
[51. 3D reconstructions <strong>of</strong> multidetector spiral CT datasets<br />
can show central bronchial stenosis for endobronchial stent<br />
placements, [5].<br />
Less Common Radiographic and CT Observations in the<br />
Thorax<br />
Radiographic and CT examinations <strong>of</strong> patients may demonstrate<br />
a number <strong>of</strong> observations that are less commonly associated<br />
with pulmonary sarcoidosis. These include a solitary mass,<br />
multiple masses, focal consolidation, cavity formation, pleural<br />
thickening, pleural effusion, and pleural calcifications, [4,5].<br />
The presence <strong>of</strong> cavities may indicate a different process than<br />
sarcoid including necrotizing sarcoid granulomatosis, superinfection,<br />
or vasculitis, [4,5]. Mycetomas may developing in<br />
upper lobe bullae and cysts in Stage 4 sarcoid. These mycetomas<br />
may present with life threatening hemoptysis. A pattern<br />
<strong>of</strong> pulmonary fibrosis indistinguishable from IPF has also been<br />
described in sarcoid, [4,51. Though unusual, unilateral lung and<br />
intrathoracic lymph node disease have also been described in<br />
sarcoid and are indistinguishable radiographically from infectious<br />
granulomatous disease and intrathoracic malignancies,<br />
[4,51. Pulmonary arterial hypertension is seen in less than 5%<br />
<strong>of</strong> patients and usually in patients with Stage 4 disease, [4,51.<br />
There is an increased rate <strong>of</strong> sarcoid recurring in a transplanted<br />
lung compared to other diseases that undergo lung<br />
transplantation therapy, [1,[8]. The frequency <strong>of</strong> recurrency has<br />
been reported to be as high as 35%, [8]. Posttransplantation<br />
immunosuppression therapy is reported to control the recurring<br />
sarcoidosis, [I]. Myocardial imaging is helpful in the 5% <strong>of</strong><br />
patients suspected <strong>of</strong> having cardiac sarcoid, [1]. Thallium 201<br />
myocardial imaging is superior to Doppler echocardiography if<br />
the detection <strong>of</strong> segmental wall motion abnormalities <strong>of</strong> the left<br />
ventricle that correspond to sarcoid induced granulomas or<br />
fibrosis in the myocardium, [1]. MR imaging <strong>of</strong> the heart has<br />
recently been shown to be effective in the detection <strong>of</strong> myocardial<br />
sarcoid lesions and the MR imaging findings may be helpful<br />
in monitoring the response <strong>of</strong> the myocardium to steroid<br />
therapy, [9].<br />
Differential Diagnosis<br />
The differential diagnosis <strong>of</strong> pulmonary sarcoid includes<br />
conditions that have preferential involvement <strong>of</strong> the perilymphatic<br />
space <strong>of</strong> the lungs and lymph node involvement in the<br />
hila <strong>of</strong> the lungs and in the mediastinum. This includes infectious<br />
granulornatous diseases, Berylliosis, lymphorna, leukemia,<br />
and lymphangitic carcinomatosis, Asymmetric involvement <strong>of</strong><br />
the lung and intrathoracic lymph nodes usually excludes malignant<br />
and infectious diseases <strong>of</strong> the thorax. Lymphangitic carcinomatosis<br />
has recently been shown to have more involvement <strong>of</strong><br />
the interlobular septae and subpleural space on HRCT than<br />
either lymphoma or sarcoid, [10]. Almost all patients with thoracic<br />
malignancies are symptomatic as opposed to asympto-