Soft tissue masses with “cyst-like” appearance on MR imaging: distinction of benign and malignant lesions

Abstract

The purpose of this study was to assess the reliability of MR imaging features in distinguishing between benign and malignant soft tissue masses that have a "cyst-like" appearance (hypointense to muscle on T1-weighted and hyperintense on T2-weighted or fluid-sensitive MR sequences). MR imaging features of 40 patients with histologically proven soft tissue masses (27 benign and 13 malignant lesions) that were hypointense to muscle on T1-weighted and hyperintense on T2-weighted or fluid-sensitive MR sequences were analysed to see if a distinction could be made between benign and malignant lesions. There were 23 females and 17 males (mean age, 56 years; age range, 23-82 years). MR imaging features analysed for statistical significance included lesion size, lesion homogeneity, presence of lobulation, depth in relation to fascia and border definition. Clinical assessment included the age and sex of the patient and location of the lesion. Statistically significant MR imaging features favouring a diagnosis of a malignant lesion included larger average dimension of the mass (P < or = 0.004), larger greatest dimension of the mass (P < or = 0.028) and heterogeneity of the lesion on T1-weighted sequences (P = 0.017). The most statistically significant predictor of malignancy was the larger average dimension of the mass.

Soft-Tissue Tumors and Tumorlike Lesions: A Systematic Imaging Approach

“…Water and water-filled masses are T2 hyperintense due to the prolonged T2 relaxation time of water. However, it is important to realize that some solid masses can also appear to be quite T2 hyperintense (82)(83)(84). Thus, the differential diagnosis for lesions that are predominantly T2 hyperintense includes not only fluid-filled lesions (eg, ganglia, synovial cysts, and seromas) but also solid lesions (eg, myxomas, myxoid sarcomas, some PNSTs, and small synovial sarcomas) (29,83,85).…”

“…However, it is important to realize that some solid masses can also appear to be quite T2 hyperintense (82)(83)(84). Thus, the differential diagnosis for lesions that are predominantly T2 hyperintense includes not only fluid-filled lesions (eg, ganglia, synovial cysts, and seromas) but also solid lesions (eg, myxomas, myxoid sarcomas, some PNSTs, and small synovial sarcomas) (29,83,85). Because of the relatively homogeneous hyperintensity seen in some of these solid lesions, they can be mistaken for fluid-filled structures and have been termed cystlike lesions by some authors (83).…”

“…Thus, the differential diagnosis for lesions that are predominantly T2 hyperintense includes not only fluid-filled lesions (eg, ganglia, synovial cysts, and seromas) but also solid lesions (eg, myxomas, myxoid sarcomas, some PNSTs, and small synovial sarcomas) (29,83,85). Because of the relatively homogeneous hyperintensity seen in some of these solid lesions, they can be mistaken for fluid-filled structures and have been termed cystlike lesions by some authors (83). Other tissues that can mimic fluid on T2-weighted MR images are hyperemic synovium (75) and hyaline cartilage (39).…”

“…If a mass that is T2 hyperintense demonstrates internal enhancement, either homogeneous or heterogeneous, then soft-tissue masses (eg, intramuscular myxomas, myxoid sarcomas, PNSTs, and synovial sarcomas) should be considered (29,82,83,85,89). Myxoid material comprises a gelatinous matrix stroma that has high levels of hyaluronic acid and immature collagen fibers and can occur in a variety of benign and malignant lesions (83,89,90). Because of its high water content, myxoid material appears hyperintense on T2-weighted MR images.…”

Characterization of indeterminate soft tissue masses referred for biopsy: What is the added value of contrast imaging at 3.0 tesla?

“…Other MRI features such as sharp margins, subcutaneous or fascial location, lack of perilesional edema and homogenous T2 signal intensity suggested a benign soft tissue tumor, but the authors warned against blindly using these MRI features in the clinical setting because of poor reliability of these MRI features. 4 Other studies, unlike our investigation, have included select populations for investigation, such as myxoid and cystic-appearing masses, [21][22][23] lipomatous lesions, [24][25][26] peripheral nerve sheath tumors, 27 desmoid fibromatoses, or solely malignancies. 6 The generalization of data from such studies to the population of patients that presents with an "indeterminate" STM, is questionable.…”