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Age / Sex : 36 / F
Age / Sex : 36/F
Chief complaint
: palpable mass in right back
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 : Yeo Ju Kim, Inha University Hospital
Diagnosis: Deep extraabdominal fibromastosis
Discussion
Findings:
On MRI, there is heterogeneous signal
intensity mass in right longissimus and right iliocostalis muscle with ill-defined
infiltrative margins. It has bands of low signal intensity on both T1 and T2
weighted images. It shows diffuse enhancement following contrast material
administration but the low signal intensity bands are not enhanced. Adjacent
bony structures are within normal limit.
Differential Diagnosis: fibrous lesion with a high collagen contents
Diagnosis:
Deep extraabdominal fibromatosis
Discussion
The
fibromastoses are classified on the basis of their anatomic location as either
superficial or deep by the WHO. The superficial group includes palmar, plantar,
penile fibromatosis and knuckle pads. The deep or musculoaponeurotic
fibromatoses include extraabdominal. abdominal, and intraabdominal
fibromatosis. The WHO refers to all of these deep fibromatosis as the desmoids-type
fibromatoses.
Deep extraabdominal fibromatosis
1) Location : typically affect the fascia, septae, and aponeuroses between
muscle.
It may occur anywhere with
approximately 70% of cases involving the extremities:shoulder and upper
arm(28%), chest wall/paraspinal(17%), thigh(12%), head/neck(10~23%), knee(7%), buttock/hip (6%), lower leg(5%), forearm (4%).
2) Age: young adults (puberty ~40 years,
peak incidence: 25~ 35years)
3) Synchronous multicentric lesions: 5~15%
4) Gross pathology: Lesions are usually deep to
fascia or aponeurosis and growth may extend along the areas with poorly
circumscribed margin and infiltrative growth. Variable amount of intermingled
collagen is seen. Other changes, such as myxoid change, focal hemorrhage, vascularity,
and focal inflammation, can be seen. The relationship to surrounding tissue is
marked by interdigitating infiltrative growth, extension fascial planes
5) Prognosis:
local recurrence: 19~77%
5 years survival: > 90%
However, despite this lesions non-malignant potential, local
recur and involvement of vital local structure can lead to patient demise
6) Radiographic finding: normal or nonspecific
soft tissue density with or without adjacent bony change
Bone change: 6-37%,
pressure erosion and scalloping
without invasion or destruction or stimulation of the bone surface producing
frond-like periosteal reaction
7) USG: Ill defined hypoechoic mass
with posterior shadowing and hypervascularity
8) CT: nonspecific soft tissue mass
with poorly defined margin with well enhancement
Abundant capillary network of
fibrous tumor is suggested as an explanation of the increased attenuation
following contrast administration
9) MR: Best radiologic modality
Heterogeneous intramuscular mass (well- defined or ill-
defined) with non-enhancing bands of low signal on all pulse sequences and
linear fascial extension
i)
Heterogeneous
signal intensity on T1 and T2 weighed image
è reflecting varying proportions and
distribution of collagen, spindle cells, mucopolysaccharide within the tumor.
ii)
Decreased
signal intensity band on all pulse sequences without enhancement
è reflecting areas of dense collagen
iii)
Moderate to
marked enhancement
è corresponding to the cellular
portion of the lesion
iv)
No significant enhancement can be seen in 10%
v) Fascial tail sign: extension of tumor along
fascia (it can be seen in nodular fasciitis but it is usually a subcutaneous
lesion)
References:
Kransdorf MJ, Murphey MD, Imaging of soft
tissue tumors 2nd edition, Lippincott Willians & Wilkins,
2006:224-226
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