대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Mediastinal desmoid tumor

Radiologic Findings

Fig 1-2. CT scan shows approximately 6 cm sized hypoattenuating mass in the highest mediastinum.
Fig 3-7. On MRI, the mass shows midly heterogeneous intermediate signal intensity on T2 weighted image and hypointense signal intensity on T1 weighted images. It also shows diffusion restriction and moderate contrast enhancement. No definite invasion of adjacent structures. DWI: diffusion weighted image, FS: fat suppression

Brief Review

Desmoid tumors, also known as aggressive fibromatosis, are a heterogeneous group of rare and benign soft tissue tumors caused by monoclonal proliferation of well-differentiated fibroblasts. They primarily arise from connective tissues in adults aged 25–35 years.
MR imaging provides better soft-tissue contrast resolution and allows an accurate evaluation of the relationship between the tumor and surrounding structures. Desmoid tumors usually has heterogeneous signal intensity that likely reflects the different amounts and variable distribution of spindle-shaped cells, extracellular collagen, and myxoid matrix. Early-stage lesions are more cellular and have a predominantly hyperintense signal on T2 weighted images. As desmoid tumors evolve, collagen deposition increases and cellularity and extracellular spaces decrease, with a resultant decrease in signal intensity on T2 weighted images. The predominant T2 signal intensity of most tumors is intermediate, between that of skeletal muscle and that of subcutaneous fat. Hypointense bands are often visible on T2 weighted images, which histologically correspond to dense collagen bundles. Tumor enhancement following administration of gadolinium-based contrast agents is generally moderate to marked.
Treatment options range from active surveillance to surgery, though the optimal strategy remains controversial and patient-specific.

References

1. Dinauer PA, Brixey CJ, Moncur JT, Fanburg-Smith JC, Murphey MD. Pathologic and MR imaging features of benign fibrous soft-tissue tumors in adults. Radiographics. 2007 Jan-Feb;27(1):173-87. doi: 10.1148/rg.271065065.
2. Lee JH, Jeong JS, Kim SR, Jin GY, Chung MJ, Kuh JH, Lee YC. Mediastinal Desmoid Tumor With Remarkably Rapid Growth: A Case Report. Medicine (Baltimore). 2015 Dec;94(52):e2370. doi: 10.1097/MD.0000000000002370.

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