Magnetic resonance imaging of intramuscular myxoma with histological comparison and a review of the literature.
OBJECTIVE
To evaluate the magnetic resonance (MR) features of intramuscular myxoma (IM) compared with its pathological findings.


METHODS
Two radiologists retrospectively reviewed records and imaging studies of patients with histologically proven IM. Two radiologists also analyzed by consensus all the MR studies (pre- and post-contrast T1-weighted and T2-weighted sequences) and a pathologist reviewed the available histological material.


METHODS
Seventeen patients with 18 histologically proven IM were reviewed. Histological samples of 11 of these 18 tumors were available for pathological analysis.


RESULTS
There were 14 women and three men, with a mean age of 58.9 years. IM involved predominantly the thigh (n=10). MR imaging showed well-circumscribed intramuscular masses, hypointense on T1-weighted and hyperintense on T2-weighted images. Eleven masses were homogeneous and seven slightly heterogeneous due to fibrous septa. Enhanced MR imaging demonstrated three different patterns: peripheral enhancement (n=1), peripheral and patchy internal enhancement (n=7) or peripheral and linear internal enhancement (n=4). Intratumoral cysts were detected in four masses. MR imaging showed the presence of a pseudocapsule (n=12), fat around the lesion (n=16) and peritumoral edema (n=16). Histologically, all the tumors were hypocellular, hypovascular and myxoid. Peripheral areas of collagenous fibers formed a partial capsule and IM often merged into surrounding muscular fibers. More cellular tumors and those with scanty myxoid stroma tended to show a more prominent internal enhancement.


CONCLUSIONS
IM shows several recognizable MR features which suggest its diagnosis.
Luna
A
A
MR Unit, Clínica Las Nieves, Sercosa, Carmelo Torres 2, 23007 Jaén, Spain. aluna70@sercosa.com
Martinez
S
S
Bossen
E
E
D000273:Adipose Tissue / Q000473:pathology; D000328:Adult; D000368:Aged; D003094:Collagen; D003287:Contrast Media; D004487:Edema / Q000175:diagnosis; D005260:Female; D005355:Fibrosis; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000473:pathology; D019042:Muscle Neoplasms / Q000175:diagnosis* / Q000473:pathology; D009214:Myoma / Q000175:diagnosis* / Q000473:pathology; D012189:Retrospective Studies; D013848:Thigh / Q000473:pathology
D003287:Contrast Media; D003094:Collagen; D019786:Gadolinium DTPA