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Age / Sex : 47 / F
Age / Sex :
47/F
Chief complaint :
Multiple palpable massses of extremities
1) What is your impression?
Two weeks later, you can see the final diagnosis with a brief discussion of this case.
* Send Application Answers to In Sook Lee, MD (lis@pusan.ac.kr)
Courtesy : Jin Gyoon Park, Chonnam National University Hospital
Diagnosis: Muscular sarcoidosis
Discussion
Findings:
1) On ultrasonograms of right calf, transverse
image shows a nodular lesion in calf muscle with a hyperechoic center and a
hypoechoic peripheral zone. Longitudinal image shows three stripes with a
hyperechoic inner stripe and hypoechoic outer stripes.
2) On MR images of right thigh, there are many
nodular lesions of muscles with or without hypointense center on axial T1WI and
T2WI images. The hypointense centers do not enhance after intravenous contrast
administration. The peripheral area of the nodules is slightly hyperintense
compared to muscle on T1WI, with high signal intensity on T2WI and homogeneous
enhancement after intravenous contrast administration. Coronal images show the “three
stripes” sign, consisting of a hypointense inner stripe and hyperintense outer
stripes.
3) PET-CT shows multiple hypermetabolic nodules
in muscles of both lower legs.
Differential Diagnosis:
Diagnosis:
Sarcoidosis
Discussion:
Sarcoidosis is a systemic granulomatous
disorder which can affect multiple organs. Muscle involvement is rare and
occurs in 1.4 – 6% of patients with sarcoidosis. There are three main clinical
types of muscular sarcoidosis: an acute myositic form, a diffuse atrophic form,
and a nodular form. Clinical symptoms are often absent.
The acute
myositis type occurs in early stage of sarcoidosis. MR imaging is usually
negative, presumably because of the sparse distribution and small size of
epithelioid cell granulomas.
In the
diffuse atrophic type, the muscles of proximal portions of the extremities are
frequently involved. MR imaging finding is muscle atrophy with fatty
replacement.
The least
common form is the nodular type. Presenting as a single or multiple sarcoid
nodules. These nodules appear elongated, and extend along muscle fibers. On
ultrasound examination, sarcoid nodules present with a hyperechoic center and a
hypoechoic peripheral zone. They may also present with well-defined borders and
an overall hypoechoic aspect.
On MR
imaging, the nodules may have a star-shaped hypointense center on all axiall
pulse sequences(“dark star” sign), which is believed to correspond with fibrous
tissue, and does not enhance after intravenous contrast administration. However,
this central structure is not present in the acute stage of the disease. It can
also be absent in small nodules(<10 mm), presumably because of the short
time of granumatous inflammation in these small structures. The peripheral area
of the nodules is slightly hyperintense compared to muscle on T1-weighted
images, with homogeneous high signal intensity on T2-weighted images. There is homogeneous
enhancement after intravenous contrast administration, secondary to the high
celluarlity of granulomas and edema. Coronal and sagittal images may show the “three
stripes” sign, consisting of a hypointense inner stripe and hyperintense outer
stripes.
References:
1.
Heckmann JG,
Stefan H, Heuss D, Hopp P. Neundorfer B. Isolated muscular sarcoidosis. EurJ Neurol 2001; 4:365-366
2.
Otake S.
Sarcoidosis involving skeletal muscle: imaging findings and relative value of
imaging procedure. AJR 1994; 2:369-375
3.
Otake S,
Banno T, Ohba S, Noda M, Yamamoto M. Muscular sarcoidosis: findings at MR
imaging. Radiology 1990;1:45-148
4.
Tohme-Noun
C, Le Breton C, Sobotka A, Boumenir Z, Milleron B, Carette M. Imaging findings
in three cases of muscular sarcoidosis. AJR 2004;183:995-999
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