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Age / Sex : 19 / F
Chief complaint : Palpable mass
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Courtesy: Soo-Jung Choi, GangNeung Asan Hospital
Diagnosis: Fibromatosis
Discussion
Findings: MR
imagings show a intramuscular T2 heterogenously low signal intensity mass along
the fascial plane of the deltoid muscle. Band like T2 dark signal intensity
lesions are noted in the mass. The mass is strongly enhanced after contrast
material administration and extended into the subcutaneous fat layer and along
the deltoid muscle.
Differential Diagnosis:
Diagnosis:
Fibromatosis (Desmoid)
Discussion: Fibromatoses
are a group of benign fibrous tissue proliferations characterized by
infiltrative growth and a tendency to recur locally without metastasis. The two
major groups are superficial (fascial) and deep (musculoaponeurotic). The deep
fibromatoses are characterized as extraabdominal, abdominal, and
intraabdominal. Extraabdominal desmoid-type fibromatosis (also known as
extraabdominal desmoid, well-differentiated nonmetastasizing fibrosarcoma, and
aggressive fibromatosis) arises from the connective tissue of muscle and its
overlying aponeurosis or fascia. Abdominal fibromatosis involves the
musculoaponeurotic structures of the abdominal wall. It is similar to
extraabdominal fibromatosis in gross appearance and histologic features, but it
is classified separately because of its unique patient population; that is, it
classically occurs in young women during or following pregnancy.
Desmoid-type fibromatoses are commonly
intermuscular masses of deep soft tissue, are iso- to mildly hyperintense
relative to muscle on T1-weighted images, and iso- to hyperintense relative to
muscle on T2-weighted images (9). One case series of 47 soft-tissue masses revealed seven lesions that
displayed a lower signal than that of muscle on T2-weighted images. These
lesions had less cellularity and more collagen than did those tumors with high
T2 signal intensity. The unusual
characteristic of heterogeneous, bandlike low-signal-intensity areas on T1- and
T2-weighted images is a distinguishing feature of desmoid-type fibromatosis.
The nonenhancing hypointense bands are thought to represent areas of increased
fibrosis composed of a higher degree of collagen content.
References:
1.
McDonald ES, Yi ES, Wenger DE. Extraabdominal Desmoid-type
Fibromatosis. Radiographics. 2008; 28(3):901-906.
2.
Fibromatoses. In: Weiss SW,
Goldblum JR, eds. Enzinger and Weiss’s soft tissue tumors. 4th ed. St Louis,
Mo: Mosby, 2001; 320–329.
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