Sarcoidosis

 Most common site of involvement is lung


image Also lymph nodes, spleen, liver, eyes, skin, salivary glands, nervous system, heart

image Less common: Bones, GI, GU


• Most common abdominal imaging finding is nonspecific hepatosplenomegaly
image Diffuse parenchymal heterogeneity or multinodular pattern in liver, spleen, or both

image Multiple low-attenuation nodules on CT and MR

image Upper abdominal lymphadenopathy is often present

• Advanced disease may cause or simulate cirrhosis




CLINICAL ISSUES




• Diverse clinical presentations
image Classic: Young African American woman with chest symptoms

• Hypercalcemia, hypercalciuria, hypergammaglobulinemia, anemia, leukopenia

• 3 well-recognized, but uncommon, hepatic syndromes: Chronic intrahepatic cholestasis, portal hypertension, and Budd-Chiari syndrome

• Angiotensin-converting enzyme elevated in 60% of patients with sarcoidosis; nonspecific and generally not useful in following course of disease


DIAGNOSTIC CHECKLIST




• Both lung disease and nodes may be FDG avid and mimic malignancy

• Do not assume that heterogeneous hepatomegaly and abdominal lymphadenopathy are always malignant

image
(Left) Axial NECT shows bilateral hilar lymphadenopathy image in the thorax, including some calcification.


image
(Right) The lung windows in the same case show micronodularity image along the bronchial tree, characteristic of pulmonary sarcoid.

image
(Left) Axial CECT in the same case shows a nodular liver with widened fissures; this appearance might be mistaken for cirrhosis. Subtle hypodense foci in the liver and spleen indicate the granulomatous nature of the pathology.


image
(Right) In H&E stain of a photomicrograph, a large epithelioid, noncaseating granuloma is seen in a liver biopsy from a case of sarcoidosis with ductopenia. (Courtesy J. Misdraji, MD.)


TERMINOLOGY


Synonyms




• Boeck sarcoid


Definitions




• Relatively common, chronic, multisystem disease of unknown origin characterized by presence of noncaseating epithelioid granulomas


IMAGING


General Features




• Best diagnostic clue
image Multifocal small hypodense lesions (granulomas) in liver and spleen in young patient with lymphadenopathy

• Location
image Can affect almost every organ

image Most common: Lung
– Common: Lymph nodes, spleen, liver, eyes, skin, salivary glands

– Less common: Bones, nervous system, heart, GI, GU

• Size
image Granulomas are generally 50-300 µm
– Large nodules may be up to 2 cm

– Usually remain smaller than 2 mm in diameter, even though they may aggregate into larger clusters

• Key concepts
image Granulomas are usually inconspicuous and featureless

image It has been suggested that imaging-visible nodules do not simply represent aggregate of microscopic granulomas
– May instead represent more vigorous immunologic response to unknown causative agent of sarcoidosis

– Larger coalescence of granulomas are coupled with exuberant deposition of reticulin, evolving to fibrosis around granulomatous aggregates


CT Findings




• Lymphadenopathy
image Upper abdominal adenopathy is common, may simulate lymphoma

image Usually accompanied by mediastinal adenopathy

• Hepatosplenic involvement
image Most common finding is nonspecific hepatosplenomegaly
– Liver involvement can be found on biopsy in up to 75%

– Splenic involvement in ∼ 25%

image Diffuse parenchymal heterogeneity or multinodular pattern in liver, spleen, or both

image Innumerable small (< 15 mm) low-density nodules before contrast agent injection
– May become isodense with liver parenchyma on delayed CECT

image Advanced disease may cause or simulate cirrhosis
– May especially mimic primary biliary cirrhosis (lace-like fibrosis plus lymphadenopathy)

• Thoracic
image Bilateral hilar and mediastinal lymphadenopathy (especially right paratracheal)

image Interstitial ± alveolar disease
– Beading or irregular thickening of bronchovascular bundles

image May progress to conglomerate masses, bronchiectasis, pulmonary nodules ± cavitation

image Pleural effusion unusual (< 5%)

• Gastrointestinal
image GI tract involvement in 1% of cases

image Mostly gastric; ulceration or mural infiltration

image Usually asymptomatic

• Genitourinary
image Most common: Calculi due to hypercalcemia

image Uncommon: Interstitial nephritis (striated nephrogram)

image Rare: Focal, soft tissue, renal masses


MR Findings




• T1WI
image When visualized, nodules appear hypointense to adjacent liver parenchyma
– May disappear on delayed contrast-enhanced T1WI

• T2WI
image Hypointense nodules

image Lace-like fibrosis (hyperintense bands)


Ultrasonographic Findings




• Grayscale ultrasound
image Nonspecific, diffuse parenchymal heterogeneity
– May mimic steatosis or cirrhosis

image Granulomas: Hypoechoic nodules


Nuclear Medicine Findings




• FDG PET scan
image Both lung disease and nodes may be FDG avid and mimic malignancy

• Gallium scan
image Ga-67 localizes in areas of granulomatous infiltrates; however, nonspecific finding


Other Modality Findings




• Cholangiography may be useful in evaluation of patients with cholestatic sarcoid liver disease
image Diffuse intrahepatic biliary strictures


Imaging Recommendations



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Nov 16, 2016 | Posted by in GASTROINTESTINAL IMAGING | Comments Off on Sarcoidosis

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