Soft-Tissue Myxomatous Lesions: Review of Salient Imaging Features with Pathologic Comparison

Abstract

Myxoid soft-tissue lesions are a heterogeneous group of benign and malignant mesenchymal tumors with an abundance of extracellular mucoid material. These lesions may mimic cysts on radiologic evaluation because of the high water content, and histopathologic features also overlap. Benign myxoid lesions include intramuscular myxoma, synovial cyst, bursa, ganglion, and benign peripheral nerve sheath tumor, including neurofibroma and schwannoma. Malignant entities include myxoid liposarcoma, myxoid leiomyosarcoma, myxoid chondrosarcoma, ossifying fibromyxoid tumor, and myxofibrosarcoma. Some syndromes are associated with myxoid soft-tissue lesions, such as Mazabraud syndrome in patients with soft-tissue myxomas and fibrous dysplasia. Certain discriminating features, such as intralesional fat in a myxoid liposarcoma, perilesional edema and a rim of fat in soft-tissue myxoma, and the swirled T2-weighted signal intensity and enhancement pattern of aggressive angiomyxoma, assist the radiologist in differentiating these lesions. The presence of an internal chondroid matrix or incomplete peripheral ossification may suggest myxoid chondrosarcoma or ossifying fibromyxoid tumor, respectively. The entering-and-exiting-nerve sign is suggestive of a peripheral nerve sheath tumor. Communication with a joint or tendon sheath and peripheral enhancement may indicate a ganglion or synovial cyst. This article (a) reviews the magnetic resonance, computed tomographic, and ultrasonographic imaging characteristics of soft-tissue myxomatous lesions, emphasizing imaging findings that can help differentiate benign and malignant lesions; (b) presents differential diagnoses; and (c) provides pathologic correlation.

Extrauterine myxoid leiomyoma mimicking an aggressive angiomyxoma

“…AAM shares very similar radiological characteristics with ML. It demonstrates high T2-weighted signal intensity secondary to a myxoid matrix with a classically described laminated or swirled appearance as suggested in our case [16,17] . AAM also shows low FDG avidity [16] .…”

The Magnetic Resonance (MR) Imaging Features of Myxoid Liposarcoma Arising from the Mesentery: a Case Report

“…Myxoid leiomyosarcoma and myxoma should be included in the differential diagnosis of our case because it can appear as a cystic mass on the T1-and T2-weighted MR images (8). Those two tumors usually show various imaging patterns so the differentiation of myxoma or myxoid leiomyosarcoma from myxoid liposarcoma is quite difficult.…”

Juxta-articular myxoma of the wrist

“…1 Computed tomography (CT) typically shows a lesion denser than water but less dense than muscle. 8 The lesion on MRI is iso-to hypointense on precontrast T1W, inhomogeneously hyperintense on T2W, and demonstrates mild to moderate diffuse or peripheral contrast enhancement. 8 Typical MRI findings also include mild perilesional oedema, owing to an incomplete fibrous capsule, and a split-fat sign as a result of adjacent muscle atrophy.…”

“…8 The lesion on MRI is iso-to hypointense on precontrast T1W, inhomogeneously hyperintense on T2W, and demonstrates mild to moderate diffuse or peripheral contrast enhancement. 8 Typical MRI findings also include mild perilesional oedema, owing to an incomplete fibrous capsule, and a split-fat sign as a result of adjacent muscle atrophy. 8 JAM and intramuscular myxoma share the same histological characteristics, but are differentiated by lesion location and the high recurrence rate of JAM.…”

“…8 Typical MRI findings also include mild perilesional oedema, owing to an incomplete fibrous capsule, and a split-fat sign as a result of adjacent muscle atrophy. 8 JAM and intramuscular myxoma share the same histological characteristics, but are differentiated by lesion location and the high recurrence rate of JAM. The differential diagnosis of a lesion with imaging findings of a soft-tissue mass that mimics a cyst includes synovial cyst, bursa, ganglion, neurogenic neoplasms, myxoid liposarcomas and myxoid malignant fibrous histiocytoma (MFH).…”